Survival trends for patients diagnosed with cutaneous malignant melanoma in the Nordic countries 1990-2016: The NORDCAN survival studies

BACKGROUND

The survival in patients diagnosed with cutaneous malignant melanoma (CMM) has improved in the Nordic countries in the last decades. It is of interest to know if these improvements are observed in all ages and for both women and men.

METHODS

Patients diagnosed with CMM in the Nordic countries in 1990-2016 were identified in the NORDCAN database. Flexible parametric relative survival models were fitted, except for Iceland where a non-parametric Pohar-Perme approach was used. A range of survival metrics were estimated by sex, both age-standardised and age-specific.

RESULTS

The 5-year relative survival improved in all countries, in both women and men and across age. While the improvement was more pronounced in men, women still had a higher survival at the end of the study period. The survival was generally high, with age-standardised estimates of 5-year relative survival towards the end of the study period ranging from 85% in Icelandic men to 95% in Danish women. The age-standardised and reference-adjusted 5-year crude probability of death due to CMM ranged from 5% in Danish and Swedish women to 13% in Icelandic men.

CONCLUSION

Although survival following CMM was relatively high in the Nordic countries in 1990, continued improvements in survival were observed throughout the study period in both women and men and across age.

Loss in life expectancy in patients with stage II-III cutaneous melanoma in Sweden: A population-based cohort study

BACKGROUND

Survival in cutaneous melanoma (CM) is heterogeneous. Loss in life expectancy (LLE) measures impact of CM on remaining lifespan compared to general population.

OBJECTIVES

Investigating LLE in operated stage II-III CM patients.

METHODS

Data from 8061 patients (aged 40-80 years) with stage II-III CM in Sweden, diagnosed between 2005 and 2018, were analyzed (Swedish Melanoma Registry). A flexible parametric survival model estimated life expectancy and LLE.

RESULTS

Based on 2018 diagnoses, stage II and III CM patients lost 2209 and 1902 life years, respectively. LLE was higher in stage III: 5.2 versus 10.9 years (stage II vs III 60-year-old females). Younger patients had higher LLE: 10.7 versus 3.9 years (stage II CM in 40 vs 70-year-old males). In stage II, females had lower LLE than males; 50-year-old females and males stage II CM had LLE equal to 7.3 and 8.3 years, respectively. LLE increased with higher substages, stage IIB resembling IIIB and IIC resembling IIIC-D.

LIMITATIONS

Extrapolation was used to estimate LLE. Varying stage group sizes require caution.

CONCLUSIONS

Our results are both clinically relevant and easy-to-interpret measures of the impact of CM on survival, but the results also summarize the prognosis over the lifetime of a CM patient.

Non-preventable cases of breast, prostate, lung, and colorectal cancer in 2050 in an elimination scenario of modifiable risk factors

Most Western countries have increasing number of new cancer cases per year. Cancer incidence is primarily influenced by basically avoidable risk factors and an aging population. Through hypothetical elimination scenarios of multiple major risk factors for cancer, we estimated the number of new cancer cases that are non-preventable in 2050. We compare numbers of new postmenopausal breast, prostate, lung, and colorectal cancer cases in 2021 to projected numbers of new cases in 2050 under prevention scenarios regarding smoking, overweight and obesity, and alcohol consumption: no intervention, 50%, and 100% instant reduction. Cancer incidence data were derived from NORDCAN, and risk factor prevalence data from the Danish National Health Survey. Cancer projections were calculated with the Prevent program. Hypothetical 100% instant elimination of major risk factors for cancer in Denmark in 2022 will result in unchanged numbers of new breast and colorectal cancers in 2050. The number of new prostate cancers will increase by 25% compared to 2021. Unchanged risk factor levels will result in noticeable increase in cancer burden. Increase in life expectancy and age will entail an increase in cancer incidence, despite maximum effect of preventive actions in the population. Our results are important when planning future health care.

Have the recent advancements in cancer therapy and survival benefitted patients of all age groups across the Nordic countries? NORDCAN survival analyses 2002-2021

BACKGROUND

Since the early 2000s, overall and site-specific cancer survival have improved substantially in the Nordic countries. We evaluated whether the improvements have been similar across countries, major cancer types, and age groups.

MATERIAL AND METHODS

Using population-based data from the five Nordic cancer registries recorded in the NORDCAN database, we included a cohort of 1,525,854 men and 1,378,470 women diagnosed with cancer (except non-melanoma skin cancer) during 2002-2021, and followed for death until 2021. We estimated 5-year relative survival (RS) in 5-year calendar periods, and percentage points (pp) differences in 5-year RS from 2002-2006 until 2017-2021. Separate analyses were performed for eight cancer sites (i.e. colorectum, pancreas, lung, breast, cervix uteri, kidney, prostate, and melanoma of skin).

RESULTS

Five-year RS improved across nearly all cancer sites in all countries (except Iceland), with absolute differences across age groups ranging from 1 to 21 pp (all cancer sites), 2 to 20 pp (colorectum), -1 to 36 pp (pancreas), 2 to 28 pp (lung), 0 to 9 pp (breast), -11 to 26 pp (cervix uteri), 2 to 44 pp (kidney), -2 to 23 pp (prostate) and -3 to 30 pp (skin melanoma). The oldest patients (80-89 years) exhibited lower survival across all countries and sites, although with varying improvements over time.

INTERPRETATION

Nordic cancer patients have generally experienced substantial improvements in cancer survival during the last two decades, including major cancer sites and age groups. Although survival has improved over time, older patients remain at a lower cancer survival compared to younger patients.

Childbirth rates in women with myeloproliferative neoplasms

Myeloproliferative neoplasms (MPN) are associated with inferior pregnancy outcome, however, little is known about fertility and childbearing potential in women with MPN. In this study we aimed to describe reproductive patterns, as well as to quantify risk of miscarriage and stillbirth. Women aged 15-44 years with an MPN diagnosis 1973-2018, were identified in Swedish health care registers, and age-matched 1:4 to population controls. We identified 1141 women with MPN and 4564 controls. Women with MPN had a lower rate of childbirth (hazard ratio [HR] with 95% confidence interval was 0.78 (0.68-0.90)). Subgroup analysis showed that the rate was not significantly reduced in essential thrombocythemia, HR 1.02 (0.86-1.22) while the HR was 0.50 (0.33-0.76) in PV and 0.45 (0.28-0.74) in PMF. The risk of miscarriage was not significantly increased before MPN diagnosis, the HR during follow-up after diagnosis was 1.25 (0.89-1.76). Women with MPN were more likely to have had a previous stillbirth. Women with MPN had fewer children at diagnosis, and fewer children in total. In conclusion, the childbirth rate was lower among women with MPN than controls, but not among women with essential thrombocythemia.

Despite multi-disciplinary team discussions the socioeconomic disparities persist in the oncological treatment of non-metastasized colorectal cancer

BACKGROUND

The introduction of national guidelines should eliminate previously observed associations between socioeconomic status (SES) and colorectal cancer treatment. The aim of the study was to investigate whether inequalities remain.

METHODS

CRCBaSe, a register-linkage originating from the Swedish Colorectal Cancer Registry, was used to identify information on patient and tumour characteristics, for 83,460 patients with stage I-III disease diagnosed 2008-2021. SES was measured as disposable income (quartiles) and the highest level of education. Outcomes of interest were emergency surgery, multidisciplinary team (MDT) conference discussion, and oncological treatment. Differences in treatment between SES groups were explored using multivariable logistic regression adjusted for year of diagnosis, age at diagnosis, sex, civil status, comorbidities, tumour location and stage.

RESULTS

Patients in the highest income quartile had a lower risk of emergency surgery (OR 0.73 95%CI 0.68-0.80), a higher chance of being discussed at the preoperative (OR 1.39 95%CI 1.28-1.51) and postoperative MDT (OR 1.41 95%CI 1.30-1.53), receiving neoadjuvant (OR 1.15 95%CI 1.06-1.25) and adjuvant treatment (OR 2.04 95%CI 1.88-2.20). Higher education level increased the odds of MDT discussion but was not associated with oncological treatment. The proportion of patients discussed at the MDT increased, with almost all patients discussed since 2016. Despite this, treatment differences remained when patients diagnosed since 2016 were analysed separately.

CONCLUSION

There were significant differences in how patients with different SES were treated for colorectal cancer. Further action is required to investigate the drivers of these differences as well as their impact on mortality and, ultimately, eliminate the inequalities.

Including uncertainty of the expected mortality rates in the prediction of loss in life expectancy

PURPOSE

This study introduces a novel method for estimating the variance of life expectancy since diagnosis (LEC) and loss in life expectancy (LLE) for cancer patients within a relative survival framework in situations where life tables based on the entire general population are not accessible. LEC and LLE are useful summary measures of survival in population-based cancer studies, but require information on the mortality in the general population. Our method addresses the challenge of incorporating the uncertainty of expected mortality rates when using a sample from the general population.

METHODS

To illustrate the approach, we estimated LEC and LLE for patients diagnosed with colon and breast cancer in Sweden. General population mortality rates were based on a random sample drawn from comparators of a matched cohort. Flexible parametric survival models were used to model the mortality among cancer patients and the mortality in the random sample from the general population. Based on the models, LEC and LLE together with their variances were estimated. The results were compared with those obtained using fixed expected mortality rates.

RESULTS

By accounting for the uncertainty of expected mortality rates, the proposed method ensures more accurate estimates of variances and, therefore, confidence intervals of LEC and LLE for cancer patients. This is particularly valuable for older patients and some cancer types, where underestimation of the variance can be substantial when the entire general population data are not accessible.

CONCLUSION

The method can be implemented using existing software, making it accessible for use in various cancer studies. The provided example of Stata code further facilitates its adoption.

Re-ranking cancer mortality using years of life lost

Incidence and mortality are default measures to describe cancer trends. Mortality compounds incidence and survival but not age at death. We calculated years of life lost (YLL) due to one of the 10 solid tumors causing most deaths (lung, colorectal, prostate, pancreatic, breast, hepatobiliary, urinary, central nervous system, gastric, melanoma) using Swedish National Cancer and Cause of Death Registers. Comparing YLL to mortality in 2019, lung (43,152 YLL) and colorectal (32,340 YLL) remained at the top, pancreatic was up-ranked 4th to 3rd (22,592 YLL) and breast 5th to 4th (21,810 YLL), while prostate cancer was down-ranked 3rd to 5th (17,380 YLL). Assessing YLL over 2010-2019, women lost consistently more life years due to lung and pancreatic cancer. A downward colorectal cancer mortality trend was reflected as a YLL decline only in women. YLL is simple to calculate, intuitive to interpret, and expands the understanding of the cancer burden on society.

Exploring different research questions via complex multi-state models when using registry-based repeated prescriptions of antidepressants in women with breast cancer and a matched population comparison group

BACKGROUND

Multi-state models are used to study several clinically meaningful research questions. Depending on the research question of interest and the information contained in the data, different multi-state structures and modelling choices can be applied. We aim to explore different research questions using a series of multi-state models of increasing complexity when studying repeated prescriptions data, while also evaluating different modelling choices.

METHODS

We develop a series of research questions regarding the probability of being under antidepressant medication across time using multi-state models, among Swedish women diagnosed with breast cancer (n = 18,313) and an age-matched population comparison group of cancer-free women (n = 92,454) using a register-based database (Breast Cancer Data Base Sweden 2.0). Research questions were formulated ranging from simple to more composite ones. Depending on the research question, multi-state models were built with structures ranging from simpler ones, like single-event survival analysis and competing risks, up to complex bidirectional and recurrent multi-state structures that take into account the recurring start and stop of medication. We also investigate modelling choices, such as choosing a time-scale for the transition rates and borrowing information across transitions.

RESULTS

Each structure has its own utility and answers a specific research question. However, the more complex structures (bidirectional, recurrent) enable accounting for the intermittent nature of prescribed medication data. These structures deliver estimates of the probability of being under medication and total time spent under medication over the follow-up period. Sensitivity analyses over different definitions of the medication cycle and different choices of timescale when modelling the transition intensity rates show that the estimates of total probabilities of being in a medication cycle over follow-up derived from the complex structures are quite stable.

CONCLUSIONS

Each research question requires the definition of an appropriate multi-state structure, with more composite ones requiring such an increase in the complexity of the multi-state structure. When a research question is related with an outcome of interest that repeatedly changes over time, such as the medication status based on prescribed medication, the use of novel multi-state models of adequate complexity coupled with sensible modelling choices can successfully address composite, more realistic research questions.

Seasonal effects on cancer incidence and prognosis

BACKGROUND

It is unknown if the reduction in the expected number of cancer cases diagnosed during Swedish holidays are due to diagnostic delays, how different cancers are affected, and if the season of diagnosis influences long-term cancer survival. We aimed to quantify seasonal trends in incidence and excess mortality for a wide range of malignancies, requiring more or less urgent clinical management.

MATERIAL AND METHODS

This nationwide cohort study included all Swedish residents aged 20-84 in 1990-2019. Incidence and relative survival in pancreatic, colorectal, lung, urothelial, breast, and prostate cancer, together with malignant melanoma, non-Hodgkin lymphoma, and acute leukemia diagnosed during holiday and post-holiday were compared to working (reference) season. Incidence rate ratios (IRR) were estimated using Poisson regression and excess (cancer) mortality rate ratios using flexible parametric models.

RESULTS

We identified 882,980 cancer cases. Incidence declined during holiday season for all malignancies and the IRR ranged from 0.58 (95% CI 0.57-0.59 in breast to 0.92 (95% CI 0.89-0.94) in pancreatic cancer. A post-holiday increase was noted for acute leukemia, pancreatic, and lung cancer. For all malignancies except lung cancer, non-Hodgkin lymphoma, and acute leukemia, the excess mortality at 2 years from diagnosis was higher among those diagnosed during the holiday season. A tendency toward elevated short-term (0.5 years) excess mortality was noted in the post-holiday group, but long-term effects only persisted in breast cancer.

CONCLUSION

This study demonstrates lower holiday detection rates and higher mortality rates in various cancer types diagnosed during holiday season. Healthcare systems should offer a uniform level of cancer care independent of calendar season.

Age-specific survival trends and life-years lost in women with breast cancer 1990-2016: the NORDCAN survival studies

BACKGROUND

A recent overview of cancer survival trends 1990-2016 in the Nordic countries reported continued improvements in age-standardized breast cancer survival among women. The aim was to estimate age-specific survival trends over calendar time, including life-years lost, to evaluate if improvements have benefited patients across all ages in the Nordic countries.

METHODS

Data on breast cancers diagnosed 1990-2016 in Denmark, Finland, Iceland, Norway, and Sweden were obtained from the NORDCAN database. Age-standardized and age-specific relative survival (RS) was estimated using flexible parametric models, as was reference-adjusted crude probabilities of death and life-years lost.

RESULTS

Age-standardized period estimates of 5-year RS in women diagnosed with breast cancer ranged from 87% to 90% and 10-year RS from 74% to 85%. Ten-year RS increased with 15-18 percentage points from 1990 to 2016, except in Sweden (+9 percentage points) which had the highest survival in 1990. The largest improvements were observed in Denmark, where a previous survival disadvantage diminished. Most recent 5-year crude probabilities of cancer death ranged from 9% (Finland, Sweden) to 12% (Denmark, Iceland), and life-years lost from 3.3 years (Finland) to 4.6 years (Denmark). Although survival improvements were consistent across different ages, women aged ≥70 years had the lowest RS in all countries. Period estimates of 5-year RS were 94-95% in age 55 years and 84-89% in age 75 years, while 10-year RS were 88-91% in age 55 years and 69-84% in age 75 years. Women aged 40 years lost on average 11.0-13.8 years, while women lost 3.8-6.0 years if aged 55 and 1.9-3.5 years if aged 75 years.

CONCLUSIONS

Survival for Nordic women with breast cancer improved from 1990 to 2016 in all age groups, albeit with larger country variation among older women where survival was also lower. Women over 70 years of age have not had the same survival improvement as women of younger age.

Standardised survival probabilities: a useful and informative tool for reporting regression models for survival data

BACKGROUND

When interested in studying the effect of a treatment (or other exposure) on a time-to-event outcome, the most popular approach is to estimate survival probabilities using the Kaplan-Meier estimator. In the presence of confounding, regression models are fitted, and results are often summarised as hazard ratios. However, despite their broad use, hazard ratios are frequently misinterpreted as relative risks instead of relative rates.

METHODS

We discuss measures for summarising the analysis from a regression model that overcome some of the limitations associated with hazard ratios. Such measures are the standardised survival probabilities for treated and untreated: survival probabilities if everyone in the population received treatment and if everyone did not. The difference between treatment arms can be calculated to provide a measure for the treatment effect.

RESULTS

Using publicly available data on breast cancer, we demonstrated the usefulness of standardised survival probabilities for comparing the experience between treated and untreated after adjusting for confounding. We also showed that additional important research questions can be addressed by standardising among subgroups of the total population.

DISCUSSION

Standardised survival probabilities are a useful way to report the treatment effect while adjusting for confounding and have an informative interpretation in terms of risk.

Obtaining long-term stage-specific relative survival estimates in the presence of incomplete historical stage information

BACKGROUND

Completeness of recording for cancer stage at diagnosis is often historically poor in cancer registries, making it challenging to provide long-term stage-specific survival estimates. Stage-specific survival differences are driven by differences in short-term prognosis, meaning estimated survival metrics using period analysis are unlikely to be sensitive to imputed historical stage data.

METHODS

We used data from the Surveillance, Epidemiology, and End Results (SEER) Program for lung, colon and breast cancer. To represent missing data patterns in less complete registry data, we artificially inflated the proportion of missing stage information conditional on stage at diagnosis and calendar year of diagnosis. Period analysis was applied and missing stage at diagnosis information was imputed under four different conditions to emulate extreme imputed stage distributions.

RESULTS

We fit a flexible parametric model for each cancer stage on the excess hazard scale and the differences in stage-specific marginal relative survival were assessed. Estimates were also obtained from non-parametric approaches for validation. There was little difference between the 10-year stage-specific marginal relative survival estimates, regardless of the assumed historical stage distribution.

CONCLUSIONS

When conducting a period analysis, multiple imputation can be used to obtain stage-specific long-term estimates of relative survival, even when the historical stage information is largely incomplete.

Reference adjusted loss in life expectancy for population-based cancer patient survival comparisons - with an application to colon cancer in Sweden

BACKGROUND

The loss in life expectancy, LLE, is defined as the difference in life expectancy between cancer patients and that of the general population. It is a useful measure for summarising the impact of a cancer diagnosis on an individual's life expectancy. However, it is less useful for making comparisons of cancer survival across groups or over time, since the LLE is influenced by both mortality due to cancer and other causes and the life expectancy in the general population.

METHODS

We present an approach for making LLE estimates comparable across groups and over time by using reference expected mortality rates with flexible parametric relative survival models. The approach is illustrated by estimating temporal trends in LLE of colon cancer patients in Sweden.

RESULTS

The life expectancy of Swedish colon cancer patients has improved, but the LLE has not decreased to the same extent since the life expectancy in the general population has also increased. When using a fixed population and other-cause mortality, i.e. a reference-adjusted approach, the LLE decreases over time. For example, using 2010 mortality rates as the reference, the LLE for females diagnosed at age 65 decreased from 11.3 if diagnosed in 1976 to 7.2 if diagnosed in 2010, and from 3.9 to 1.9 years for women 85 years old at diagnosis.

CONCLUSION

The reference-adjusted LLE is useful for making comparisons across calendar time, or groups, since differences in other cause mortality are removed.

IMPACT

The reference-adjusted approach enhances the use of LLE as a comparative measure.

Quantifying Differences in Remaining Life Expectancy after Cancer Diagnosis, Aboriginal and Torres Strait Islanders, and Other Australians, 2005-2016

BACKGROUND

This study quantified differences in remaining life expectancy (RLE) among Aboriginal and Torres Strait Islander and other Australian patients with cancer. We assessed how much of this disparity was due to differences in cancer and noncancer mortality and calculated the population gain in life years for Aboriginal and Torres Strait Islanders cancer diagnoses if the cancer survival disparities were removed.

METHODS

Flexible parametric relative survival models were used to estimate RLE by Aboriginal and Torres Strait Islander status for a population-based cohort of 709,239 persons (12,830 Aboriginal and Torres Strait Islanders), 2005 to 2016.

RESULTS

For all cancers combined, the average disparity in RLE was 8.0 years between Aboriginal and Torres Strait Islanders (12.0 years) and other Australians (20.0 years). The magnitude of this disparity varied by cancer type, being >10 years for cervical cancer versus <2 years for lung and pancreatic cancers. For all cancers combined, around 26% of this disparity was due to differences in cancer mortality and 74% due to noncancer mortality. Among 1,342 Aboriginal and Torres Strait Islanders diagnosed with cancer in 2015 an estimated 2,818 life years would be gained if cancer survival disparities were removed.

CONCLUSIONS

A cancer diagnosis exacerbates the existing disparities in RLE among Aboriginal and Torres Strait Islanders. Addressing them will require consideration of both cancer-related factors and those contributing to noncancer mortality.

IMPACT

Reported survival-based measures provided additional insights into the overall impact of cancer over a lifetime horizon among Aboriginal and Torres Strait Islander peoples.

Assessing the impact of including variation in general population mortality on standard errors of relative survival and loss in life expectancy

Background

A relative survival approach is often used in population-based cancer studies, where other cause (or expected) mortality is assumed to be the same as the mortality in the general population, given a specific covariate pattern. The population mortality is assumed to be known (fixed), i.e. measured without uncertainty. This could have implications for the estimated standard errors (SE) of any measures obtained within a relative survival framework, such as relative survival (RS) ratios and the loss in life expectancy (LLE). We evaluated the existing approach to estimate SE of RS and the LLE in comparison to if uncertainty in the population mortality was taken into account.

Methods

The uncertainty from the population mortality was incorporated using parametric bootstrap approach. The analysis was performed with different levels of stratification and sizes of the general population used for creating expected mortality rates. Using these expected mortality rates, SEs of 5-year RS and the LLE for colon cancer patients in Sweden were estimated.

Results

Ignoring uncertainty in the general population mortality rates had negligible (less than 1%) impact on the SEs of 5-year RS and LLE, when the expected mortality rates were based on the whole general population, i.e. all people living in a country or region. However, the smaller population used for creating the expected mortality rates, the larger impact. For a general population reduced to 0.05% of the original size and stratified by age, sex, year and region, the relative precision for 5-year RS was 41% for males diagnosed at age 85. For the LLE the impact was more substantial with a relative precision of 1286%. The relative precision for marginal estimates of 5-year RS was 3% and 30% and for the LLE 22% and 313% when the general population was reduced to 0.5% and 0.05% of the original size, respectively.

Conclusions

When the general population mortality rates are based on the whole population, the uncertainty in the estimates of the expected measures can be ignored. However, when based on a smaller population, this uncertainty should be taken into account, otherwise SEs may be too small, particularly for marginal values, and, therefore, confidence intervals too narrow.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12874-022-01597-7).

Five ways to improve international comparisons of cancer survival: lessons learned from ICBP SURVMARK-2

BACKGROUND

Comparisons of population-based cancer survival between countries are important to benchmark the overall effectiveness of cancer management. The International Cancer Benchmarking Partnership (ICBP) Survmark-2 study aims to compare survival in seven high-income countries across eight cancer sites and explore reasons for the observed differences. A critical aspect in ensuring comparability in the reported survival estimates are similarities in practice across cancer registries. While ICBP Survmark-2 has shown these differences are unlikely to explain the observed differences in cancer-specific survival between countries, it is important to keep in mind potential biases linked to registry practice and understand their likely impact.

METHODS

Based on experiences gained within ICBP Survmark-2, we have developed a set of recommendations that seek to optimally harmonise cancer registry datasets to improve future benchmarking exercises.

RESULTS

Our recommendations stem from considering the impact on cancer survival estimates in five key areas: (1) the completeness of the registry and the availability of registration sources; (2) the inclusion of death certification as a source of identifying cases; (3) the specification of the date of incidence; (4) the approach to handling multiple primary tumours and (5) the quality of linkage of cases to the deaths register.

CONCLUSION

These recommendations seek to improve comparability whilst maintaining the opportunity to understand and act upon international variations in outcomes among cancer patients.

Assessing lead time bias due to mammography screening on estimates of loss in life expectancy

BACKGROUND

An increasingly popular measure for summarising cancer prognosis is the loss in life expectancy (LLE), i.e. the reduction in life expectancy following a cancer diagnosis. The proportion of life lost (PLL) can also be derived, improving comparability across age groups as LLE is highly age-dependent. LLE and PLL are often used to assess the impact of cancer over the remaining lifespan and across groups (e.g. socioeconomic groups). However, in the presence of screening, it is unclear whether part of the differences across population groups could be attributed to lead time bias. Lead time is the extra time added due to early diagnosis, that is, the time from tumour detection through screening to the time that cancer would have been diagnosed symptomatically. It leads to artificially inflated survival estimates even when there are no real survival improvements.

METHODS

In this paper, we used a simulation-based approach to assess the impact of lead time due to mammography screening on the estimation of LLE and PLL in breast cancer patients. A natural history model developed in a Swedish setting was used to simulate the growth of breast cancer tumours and age at symptomatic detection. Then, a screening programme similar to current guidelines in Sweden was imposed, with individuals aged 40-74 invited to participate every second year; different scenarios were considered for screening sensitivity and attendance. To isolate the lead time bias of screening, we assumed that screening does not affect the actual time of death. Finally, estimates of LLE and PLL were obtained in the absence and presence of screening, and their difference was used to derive the lead time bias.

RESULTS

The largest absolute bias for LLE was 0.61 years for a high screening sensitivity scenario and assuming perfect screening attendance. The absolute bias was reduced to 0.46 years when the perfect attendance assumption was relaxed to allow for imperfect attendance across screening visits. Bias was also present for the PLL estimates.

CONCLUSIONS

The results of the analysis suggested that lead time bias influences LLE and PLL metrics, thus requiring special consideration when interpreting comparisons across calendar time or population groups.

A way to explore the existence of "immortals" in cancer registry data - An illustration using data from ICBP SURVMARK-2

BACKGROUND

Accurately recorded vital status of individuals is essential when estimating cancer patient survival. When deaths are ascertained by linkage with vital statistics registers, some may be missed, and such individuals will wrongly appear to be long-term survivors, and survival will be overestimated. Interval-specific relative survival that levels off above one indicates that the survival among the cancer patients is better than expected, which could be due to the presence of immortals.

METHODS

We included colon cancer cases diagnosed in 1995-1999 within the 19 jurisdictions in seven countries participating in ICBP SURVMARK-2, with follow-up information available until end-2015. Interval-specific relative survival was estimated for each year following diagnosis, by country and age group at diagnosis.

RESULTS

The interval-specific relative survival levels off at 1 for all countries and age groups, with two exceptions: for the age group diagnosed at age 75 years and above in Ireland, and, to a lesser extent, in New Zealand.

CONCLUSION

Overall, a subset of immortals are not apparent in the early years within the ICBP SURVMARK-2 study, except for possibly in Ireland. We suggest this approach as one strategy of exploring the existence of immortals, and to be part of routine checks of cancer registry data.

Non-parametric estimation of reference adjusted, standardised probabilities of all-cause death and death due to cancer for population group comparisons

BACKGROUND

Ensuring fair comparisons of cancer survival statistics across population groups requires careful consideration of differential competing mortality due to other causes, and adjusting for imbalances over groups in other prognostic covariates (e.g. age). This has typically been achieved using comparisons of age-standardised net survival, with age standardisation addressing covariate imbalance, and the net estimates removing differences in competing mortality from other causes. However, these estimates lack ease of interpretability. In this paper, we motivate an alternative non-parametric approach that uses a common rate of other cause mortality across groups to give reference-adjusted estimates of the all-cause and cause-specific crude probability of death in contrast to solely reporting net survival estimates.

METHODS

We develop the methodology for a non-parametric equivalent of standardised and reference adjusted crude probabilities of death, building on the estimation of non-parametric crude probabilities of death. We illustrate the approach using regional comparisons of survival following a diagnosis of rectal cancer for men in England. We standardise to the covariate distribution and other cause mortality of England as a whole to offer comparability, but with close approximation to the observed all-cause region-specific mortality.

RESULTS

The approach gives comparable estimates to observed crude probabilities of death, but allows direct comparison across population groups with different covariate profiles and competing mortality patterns. In our illustrative example, we show that regional variations in survival following a diagnosis of rectal cancer persist even after accounting for the variation in deprivation, age at diagnosis and other cause mortality.

CONCLUSIONS

The methodological approach of using standardised and reference adjusted metrics offers an appealing approach for future cancer survival comparison studies and routinely published cancer statistics. Our non-parametric estimation approach through the use of weighting offers the ability to estimate comparable survival estimates without the need for statistical modelling.

Self-reported arm and shoulder problems in breast cancer survivors in Sub-Saharan Africa: the African Breast Cancer-Disparities in Outcomes cohort study

Background

Arm and shoulder problems (ASP), including lymphedema, were common among women with breast cancer in high-income countries before sentinel lymph node biopsy became the standard of care. Although ASP impair quality of life, as they affect daily life activities, their frequency and determinants in Sub-Saharan Africa remain unclear.

Methods

All women newly diagnosed with breast cancer at the Namibian, Ugandan, Nigerian, and Zambian sites of the African Breast Cancer-Disparities in Outcomes (ABC-DO) cohort study were included. At each 3-month follow-up interview, women answered the EORTC-QLQ-Br23 questionnaire, including three ASP items: shoulder/arm pain, arm stiffness, and arm/hand swelling. We estimated the cumulative incidence of first self-reported ASP, overall and stratified by study and treatment status, with deaths treated as competing events. To identify determinants of ASP, we estimated cause-specific hazard ratios using Cox models stratified by study site.

Results

Among 1476 women, up to 4 years after diagnosis, 43% (95% CI 40–46), 36% (33–38) and 23% (20–25), respectively, self-reported having experienced arm/shoulder pain, stiffness and arm/hand swelling at least once. Although risks of self-reported ASP differed between sites, a more advanced breast cancer stage at diagnosis, having a lower socioeconomic position and receiving treatment increased the risk of reporting an ASP.

Conclusion

ASP are very common in breast cancer survivors in Sub-Saharan Africa. They are influenced by different factors than those observed in high-income countries. There is a need to raise awareness and improve management of ASP within the African setting.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01486-9.

Risk Factors for Suicide and Suicide Attempts Among Patients With Treatment-Resistant Depression: Nested Case-Control Study

The risk of suicide is elevated among patients with treatment-resistant depression (TRD). Risk factors for suicide and suicide attempts among cases and controls with TRD were investigated using data from nationwide Swedish registers. Among 119,407 antidepressant initiators with a diagnosis of depression, 15,631 patients who started a third sequential treatment trial during the same depressive episode were classified with TRD. A nested case-control study compared cases with suicide and suicide attempts with up to three closely matched controls. Sociodemographic and clinical risk factors were assessed using conditional logistic regression analyses. In all, 178 patients died by suicide and 1,242 experienced a suicide attempt during follow-up. History of suicide attempts, especially if <1 year after the attempt, was a significant independent risk factor for suicide (adjusted odds ratio [aOR], 8.9; 95% confidence interval [CI], 5.1-15.7) as were 10 to 12 years of education compared to lower education (aOR, 1.69; 95% CI, 1.02-2.81). For attempted suicide, the strongest independent risk factors were history of suicide attempts (<1 year aOR, 5.1; 95% CI, 4.0-6.5), substance abuse (aOR, 2.6; 95% CI, 2.2-3.1), personality disorders (aOR, 1.9; 95% CI, 1.5-2.3), and somatic comorbidity (aOR, 2.0; 95% CI, 1.04-3.9). Suicide attempts, especially if recent, are strong risk factors for completed suicide among patients with TRD. Established risk factors for suicide attempts were confirmed for patients with TRD.

The impact of excluding or including Death Certificate Initiated (DCI) cases on estimated cancer survival: A simulation study

BACKGROUND

Population-based cancer registries strive to cover all cancer cases diagnosed within the population, but some cases will always be missed and no register is 100 % complete. Many cancer registries use death certificates to identify additional cases not captured through other routine sources, to hopefully add a large proportion of the missed cases. Cases notified through this route, who would not have been captured without death certificate information, are referred to as Death Certificate Initiated (DCI) cases. Inclusion of DCI cases in cancer registries increases completeness and is important for estimating cancer incidence. However, inclusion of DCI cases will generally lead to biased estimates of cancer survival, but the same is often also true if excluding DCI cases. Missed cases are probably not a random sample of all cancer cases, but rather cases with poor prognosis. Further, DCI cases have poorer prognosis than missed cases in general, since they have all died with cancer mentioned on the death certificates.

METHODS

We performed a simulation study to estimate the impact of including or excluding DCI cases on cancer survival estimates, under different scenarios.

RESULTS

We demonstrated that including DCI cases underestimates survival. The exclusion of DCI cases gives unbiased survival estimates if missed cases are a random sample of all cancer cases, while survival is overestimated if these have poorer prognosis.

CONCLUSION

In our most extreme scenarios, with 25 % of cases initially missed, the usual practice of including DCI cases underestimated 5-year survival by at most 3 percentage points.

Exploring the impact of cancer registry completeness on international cancer survival differences: a simulation study

BACKGROUND

Data from population-based cancer registries are often used to compare cancer survival between countries or regions. The ICBP SURVMARK-2 study is an international partnership aiming to quantify and explore the reasons behind survival differences across high-income countries. However, the magnitude and relevance of differences in cancer survival between countries have been questioned, as it is argued that observed survival variations may be explained, at least in part, by differences in cancer registration practice, completeness and the availability and quality of the respective data sources.

METHODS

As part of the ICBP SURVMARK-2 study, we used a simulation approach to better understand how differences in completeness, the characteristics of those missed and inclusion of cases found from death certificates can impact on cancer survival estimates.

RESULTS

Bias in 1- and 5-year net survival estimates for 216 simulated scenarios is presented. Out of the investigated factors, the proportion of cases not registered through sources other than death certificates, had the largest impact on survival estimates.

CONCLUSION

Our results show that the differences in registration practice between participating countries could in our most extreme scenarios explain only a part of the largest observed differences in cancer survival.

Excess deaths in treatment-resistant depression

BACKGROUND

Patients with treatment-resistant depression (TRD) have an increased mortality risk compared with other patients with depression, but it is not known how this translates into absolute numbers of excess deaths.

METHODS

Swedish national registers were used to identify a cohort of 118,774 antidepressant initiators 18-69 years old with a depression diagnosis. Patients who initiated a third consecutive treatment trial were classified as having TRD. Flexible parametric survival models were used to estimate the mortality risk due to all causes and external causes (suicides and accidents), comparing TRD patients with patients with other depression while adjusting for clinical and sociodemographic covariates and including interactions with TRD, age, and Charlson comorbidity index (CCI) for a number of somatic comorbidities. Standardized survival was estimated, as were numbers of excess deaths among TRD patients within each age and comorbidity category.

RESULTS

Compared with the mortality risk of other depressed patients, patients with TRD experienced excess deaths in most age and comorbidity categories in the range of 7-16 deaths per 1000 patients during 5 years. Highest numbers for all-cause excess deaths were found among patients 18-29 years old with CCI 1, where 16 [95% confidence interval 5-28] of the expected 37 [25-48] deaths per 1000 patients were excess deaths. The majority of the excess deaths were due to external causes.

CONCLUSION

Patients with TRD experience significant numbers of excess deaths compared with other patients with depression.

Cardiovascular Incidence in 6900 Patients with Differentiated Thyroid Cancer: a Swedish Nationwide Study

INTRODUCTION

To minimize recurrence risk in differentiated thyroid cancer (DTC), TSH is usually lifelong suppressed with levothyroxine. A common consequence of this treatment is subclinical hyperthyroidism which can induce cardiovascular disease (CV). This study's aim was to compare CV incidence in DTC patients with the general population in Sweden.

MATERIALS AND METHODS

All Swedish patients diagnosed with DTC in 1987-2013 were included in the cohort study. Lifelong TSH suppression treatment was assumed to be administered to patients in compliance with prevalent national guidelines. Patients were followed from 1 year after DTC diagnosis until December 31, 2014, death, or migration. The event of interest was hospitalization due to any of the following diseases: atrial fibrillation (AF), cerebrovascular disease, cerebral infarction, ischemic heart disease, ischemic heart attack, and heart failure. Standardized incidence ratios (SIRs) were calculated to compare CV incidence between DTC patients and the general population.

RESULTS

The cohort consisted of 6900 patients with DTC. Hospitalization was increased among DTC patients for AF (SIR 1.66, CI 95% 1.41-1.94), and women faced increased hospitalization for cerebrovascular disease (SIR 1.20 CI 95% 1.04-1.38). Regarding the remaining CV diseases, no consistent difference in SIR between the groups was observed.

CONCLUSION

Compared to the general population, DTC patients have a higher incidence in AF, and female face a slightly higher incidence in cerebrovascular disease. However, there was no difference in hospitalization for other studied CV diseases between DTC patients and the general population.

Reference-adjusted and standardized all-cause and crude probabilities as an alternative to net survival in population-based cancer studies

BACKGROUND

In population-based cancer survival studies, the most common measure to compare population groups is age-standardized marginal relative survival, which under assumptions can be interpreted as marginal net survival; the probability of surviving if it was not possible to die of causes other than the cancer under study (if the age distribution was that of a common reference population). The hypothetical nature of this definition has led to confusion and incorrect interpretation. For any measure to be fair in terms of comparing cancer survival, then differences between population groups should depend only on differences in excess mortality rates due to the cancer and not differences in other-cause mortality rates or differences in the age distribution.

METHODS

We propose using crude probabilities of death and all-cause survival which incorporate reference expected mortality rates. This makes it possible to obtain marginal crude probabilities and all-cause probability of death that only differ between population groups due to excess mortality rate differences. Choices have to be made regarding what reference mortality rates to use and what age distribution to standardize to.

RESULTS

We illustrate the method and some potential choices using data from England for men diagnosed with melanoma. Various marginal measures are presented and compared.

CONCLUSIONS

The new measures help enhance understanding of cancer survival and are a complement to the more commonly used measures.

The Occurrence of Metabolic Risk Factors Stratified by Psoriasis Severity: A Swedish Population-Based Matched Cohort Study

Purpose

To assess the relative risk of metabolic risk factors in patients stratified by psoriasis severity compared with population controls.

Patients and Methods

A retrospective cohort study was conducted using national Swedish registers. Adult patients with psoriasis were selected if they had a dispensing of anti-psoriasis prescription (2007–2013) and at least one diagnosis within five years before the dispensing date. The patients with psoriasis were matched 1:10 to controls from the general population on birth year, sex, and county. The cohort was further divided into three disease severity groups (mild, moderate, or severe) based on their dispensed anti-psoriasis medication. Subjects were followed from the index date until censoring. We applied flexible parametric modeling to understand the risks of the incident comorbidities hypertension, hypercholesterolemia, and diabetes mellitus among patients with psoriasis from 6 months through 10 years. Hazard ratios and predicted risk (ie, 1 minus the survival probability) of comorbidities were reported.

Results

The hazard of hypertension, hypercholesterolemia, and diabetes mellitus is higher among psoriasis patients compared with population controls, and the hazard ratio increases with psoriasis severity. For example, HRs of hypertension for patients with mild, moderate, and severe psoriasis are 1.29 (95% CI: 1.27–1.32), 1.35 (95% CI: 1.32–1.38), and 1.73 (95% CI: 1.64–1.82), respectively. The predicted risk of hypertension, hypercholesterolemia, and diabetes mellitus among patients with severe psoriasis at year ten was 0.58 (95% CI: 0.56, 0.59), 0.33 (95% CI: 0.32, 0.35), and 0.21 (95% CI: 0.20, 0.23), respectively, while it was 0.42 (0.41, 0.43), 0.23 (0.22, 0.23), 0.11 (0.10, 0.11) among controls, respectively. The predicted risk at year ten was similar among patients with mild or moderate psoriasis.

Conclusion

The HRs and predicted risks of metabolic risk factors are higher among patients with psoriasis compared with matched controls and are more prominent among the severe psoriasis group.

Psychiatric Disorders Are Associated with Increased Risk of Sepsis Following a Cancer Diagnosis

Psychiatric disorders and infections are both common comorbidities among patients with cancer. However, little is known about the role of precancer psychiatric disorders on the subsequent risk of sepsis as a complication of infections among patients with cancer. We conducted a cohort study of 362,500 patients with newly diagnosed cancer during 2006-2014 in Sweden. We used flexible parametric models to calculate the HRs of sepsis after cancer diagnosis in relation to precancer psychiatric disorders and the analyses were performed in two models. In model 1, analyses were adjusted for sex, age at cancer diagnosis, calendar period, region of residence, and type of cancer. In model 2, further adjustments were made for marital status, educational level, cancer stage, infection history, and Charlson Comorbidity Index score. During a median follow-up of 2.6 years, we identified 872 cases of sepsis among patients with cancer with precancer psychiatric disorders (incidence rate, IR, 14.8 per 1,000 person-years) and 12,133 cases among patients with cancer without such disorders (IR, 11.6 per 1000 person-years), leading to a statistically significant association between precancer psychiatric disorders and sepsis in both the simplified (HR, 1.31; 95% CI, 1.22-1.40) and full (HR, 1.26; 95% CI, 1.18-1.35) models. The positive association was consistently noted among patients with different demographic factors or cancer characteristics, for most cancer types, and during the entire follow-up after cancer diagnosis. Collectively, preexisting psychiatric disorders were associated with an increased risk of sepsis after cancer diagnosis, suggesting a need of heightened clinical awareness in this patient group. SIGNIFICANCE: These results call for extended prevention and surveillance of sepsis among patients with cancer with psychiatric comorbidities.

On estimating the time to statistical cure

BACKGROUND

The mortality risk among cancer patients measured from the time of diagnosis is often elevated in comparison to the general population. However, for some cancer types, the patient mortality risk will over time reach the same level as the general population mortality risk. The time point at which the mortality risk reaches the same level as the general population is called the cure point and is of great interest to patients, clinicians, and health care planners. In previous studies, estimation of the cure point has been handled in an ad hoc fashion, often without considerations about margins of clinical relevance.

METHODS

We review existing methods for estimating the cure point and discuss new clinically relevant measures for quantifying the mortality difference between cancer patients and the general population, which can be used for cure point estimation. The performance of the methods is assessed in a simulation study and the methods are illustrated on survival data from Danish colon cancer patients.

RESULTS

The simulations revealed that the bias of the estimated cure point depends on the measure chosen for quantifying the excess mortality, the chosen margin of clinical relevance, and the applied estimation procedure. These choices are interdependent as the choice of mortality measure depends both on the ability to define a margin of clinical relevance and the ability to accurately compute the mortality measure. The analysis of cancer survival data demonstrates the importance of considering the confidence interval of the estimated cure point, as these may be wide in some scenarios limiting the applicability of the estimated cure point.

CONCLUSIONS

Although cure points are appealing in a clinical context and has widespread applicability, estimation remains a difficult task. The estimation relies on a number of choices, each associated with pitfalls that the practitioner should be aware of.

A unified evaluation of differential vaccine efficacy

Many infectious diseases are well prevented by proper vaccination. However, when a vaccine is not completely efficacious, there is great interest in determining how the vaccine effect differs in subgroups conditional on measured immune responses postvaccination and also according to the type of infecting agent (eg, strain of a virus). The former is often called correlate of protection (CoP) analysis, while the latter has been called sieve analysis. We propose a unified framework for simultaneously assessing CoP and sieve effects of a vaccine in a large Phase III randomized trial. We use flexible parametric models treating times to infection from different agents as competing risks and estimated maximum likelihood to fit the models. The parametric models under competing risks allow for estimation of both cumulative incidence-based contrasts and instantaneous rates. We outline the assumptions with which we can link the observable data to the causal contrasts of interest, propose hypothesis testing procedures, and evaluate our proposed methods in an extensive simulation study.

Progress in cancer survival, mortality, and incidence in seven high-income countries 1995-2014 (ICBP SURVMARK-2): a population-based study

BACKGROUND

Population-based cancer survival estimates provide valuable insights into the effectiveness of cancer services and can reflect the prospects of cure. As part of the second phase of the International Cancer Benchmarking Partnership (ICBP), the Cancer Survival in High-Income Countries (SURVMARK-2) project aims to provide a comprehensive overview of cancer survival across seven high-income countries and a comparative assessment of corresponding incidence and mortality trends.

METHODS

In this longitudinal, population-based study, we collected patient-level data on 3·9 million patients with cancer from population-based cancer registries in 21 jurisdictions in seven countries (Australia, Canada, Denmark, Ireland, New Zealand, Norway, and the UK) for seven sites of cancer (oesophagus, stomach, colon, rectum, pancreas, lung, and ovary) diagnosed between 1995 and 2014, and followed up until Dec 31, 2015. We calculated age-standardised net survival at 1 year and 5 years after diagnosis by site, age group, and period of diagnosis. We mapped changes in incidence and mortality to changes in survival to assess progress in cancer control.

FINDINGS

In 19 eligible jurisdictions, 3 764 543 cases of cancer were eligible for inclusion in the study. In the 19 included jurisdictions, over 1995-2014, 1-year and 5-year net survival increased in each country across almost all cancer types, with, for example, 5-year rectal cancer survival increasing more than 13 percentage points in Denmark, Ireland, and the UK. For 2010-14, survival was generally higher in Australia, Canada, and Norway than in New Zealand, Denmark, Ireland, and the UK. Over the study period, larger survival improvements were observed for patients younger than 75 years at diagnosis than those aged 75 years and older, and notably for cancers with a poor prognosis (ie, oesophagus, stomach, pancreas, and lung). Progress in cancer control (ie, increased survival, decreased mortality and incidence) over the study period was evident for stomach, colon, lung (in males), and ovarian cancer.

INTERPRETATION

The joint evaluation of trends in incidence, mortality, and survival indicated progress in four of the seven studied cancers. Cancer survival continues to increase across high-income countries; however, international disparities persist. While truly valid comparisons require differences in registration practice, classification, and coding to be minimal, stage of disease at diagnosis, timely access to effective treatment, and the extent of comorbidity are likely the main determinants of patient outcomes. Future studies are needed to assess the impact of these factors to further our understanding of international disparities in cancer survival.

FUNDING

Canadian Partnership Against Cancer; Cancer Council Victoria; Cancer Institute New South Wales; Cancer Research UK; Danish Cancer Society; National Cancer Registry Ireland; The Cancer Society of New Zealand; National Health Service England; Norwegian Cancer Society; Public Health Agency Northern Ireland, on behalf of the Northern Ireland Cancer Registry; The Scottish Government; Western Australia Department of Health; and Wales Cancer Network.

Survival in men diagnosed with castration resistant prostate cancer: A population-based observational study in Sweden

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Background: Data focusing on the castration resistant phase of prostate cancer (PC) outside clinical trial settings are scarce. This study aims to investigate PC-specific and overall survival (OS) in men with castration resistant prostate cancer (CRPC) on a population level. Methods: The STHLM-0 cohort (n = 400 000) with data on all prostate specific antigen (PSA) values and prostate biopsies taken in Stockholm, Sweden, from 2003 to 2015 were linked to other population registries. All men with a PC diagnosis and rising PSA after three months consecutive use of gonadotropin-releasing hormone or surgical castration were defined as CRPC (n = 1712). Kaplan-Meier was used to estimate median time-to-event and 95% confidence intervals (CI). Patients were stratified by metastasis status at PC diagnosis and multivariable Cox regression was used to adjust for clinical subgroups, including Gleason, age, T stage and calendar period (2006-2011 vs 2012-2015). Results: Metastasis at PC diagnosis was associated with shorter OS from castration resistance. From CRPC onset the median OS was 22.8 months (95% CI 21.2-25.5) and 13.1 (95% CI 11.5-14.2) months for patients without and with metastasis at PC diagnosis, respectively. The median PC-specific survival from CRPC was 30.7 (95% CI 27.9-34.7) months and 13.5 (95% CI 12.3-16.1) months for patients without and with metastasis at PC diagnosis, respectively. For patients with metastasis at PC diagnosis, factors influencing OS from CRPC were; entering CRPC stage in the later vs earlier calendar period (HR 0.61 95% CI 0.48-0.78, p < 0.001), age > 80 vs < 70 (HR 1.46, 95% CI 1.05-2.02, p < 0.02), T4 vs T1 stage (HR 1.56, 95% CI:1.02-2.37, p < 004). For patients without metastasis at PC diagnosis, developing CRPC in the later vs the earlier calendar period was associated with superior survival from CRPC (HR 0.78 95% CI 0.65-0.92, p < 0.004). Conclusions: Metastasis at PC diagnosis was associated with worse survival outcomes in CRPC patients. Individuals who became castration resistant in the later calendar period survived longer compared to those in the same stage in the earlier calendar period, most likely due to the introduction of novel agents for CRPC patients and more accurate staging methods.

Skin cancer projections and cost savings 2014-2045 of improvements to the Danish sunbed legislation of 2014

BACKGROUND

Sunbed use increases the risk of skin cancer. The Danish sunbed legislation (2014) did not include an age limit.

AIM

To model skin cancer incidences and saved costs from potential effects of structural interventions on prevalence of sunbed use.

MATERIALS AND METHODS

Survey data from 2015 were collected for 3999 Danes, representative for the Danish population in regards to age, gender and region. Skin cancer incidences were modelled in the Prevent program, using population projections, historic cancer incidence, sunbed use exposure and relative risk of sunbed use on melanoma.

RESULTS

If structural interventions like an age limit of 18 years for sunbed use or complete ban had been included in the Danish sunbed legislation in 2014, it would have reduced the annual number of skin cancer cases with 455 or 4177, respectively, while for the entire period, 2014-2045 the total reductions would be 3730 or 81 887 fewer cases, respectively. The cost savings from an age limit or ban, respectively, are 9 and 129 millions € during 2014-2045.

CONCLUSION

Legislative restrictive measures which could reduce the sunbed use exists. Danish politicians have the opportunity, supported by the population, to reduce the skin cancer incidence and thereby to reduce the future costs of skin cancer.

Avoidable cancers in the Nordic countries-the potential impact of increased physical activity on postmenopausal breast, colon and endometrial cancer

BACKGROUND

Physical activity has been shown to reduce the risk of colon, endometrial and postmenopausal breast cancer. The aim of this study was to quantify the proportion of the cancer burden in the Nordic countries linked to insufficient levels of leisure time physical activity and estimate the potential for cancer prevention for these three sites by increasing physical activity levels.

METHODS

Using the Prevent macrosimulation model, the number of cancer cases in the Nordic countries over a 30-year period (2016-2045) was modelled, under different scenarios of increasing physical activity levels in the population, and compared with the projected number of cases if constant physical activity prevailed. Physical activity (moderate and vigorous) was categorised according to metabolic equivalents (MET) hours in groups with sufficient physical activity (15+ MET-hours/week), low deficit (9 to <15 MET-hours/week), medium deficit (3 to <9 MET-hours/week) and high deficit (<3 MET-hours/week).

RESULTS

If no one had insufficient levels of physical activity, about 11,000 colon, endometrial and postmenopausal breast cancer cases could be avoided in the Nordic countries in a 30-year period, which is 1% of the expected cases for the three cancer types. With a 50% reduction in all deficit groups by 2025 or a 100% reduction in the group of high deficit, approximately 0.5% of the expected cases for the three cancer types could be avoided. The number and percentage of avoidable cases was highest for colon cancer.

CONCLUSION

11,000 cancer cases could be avoided in the Nordic countries in a 30-year period, if deficit in physical activity was eliminated.

Estimating the loss of lifetime function using flexible parametric relative survival models

Background

Within cancer care, dynamic evaluations of the loss in expectation of life provides useful information to patients as well as physicians. The loss of lifetime function yields the conditional loss in expectation of life given survival up to a specific time point. Due to the inevitable censoring in time-to-event data, loss of lifetime estimation requires extrapolation of both the patient and general population survival function. In this context, the accuracy of different extrapolation approaches has not previously been evaluated.

Methods

The loss of lifetime function was computed by decomposing the all-cause survival function using the relative and general population survival function. To allow extrapolation, the relative survival function was fitted using existing parametric relative survival models. In addition, we introduced a novel mixture cure model suitable for extrapolation. The accuracy of the estimated loss of lifetime function using various extrapolation approaches was assessed in a simulation study and by data from the Danish Cancer Registry where complete follow-up was available. In addition, we illustrated the proposed methodology by analyzing recent data from the Danish Lymphoma Registry.

Results

No uniformly superior extrapolation method was found, but flexible parametric mixture cure models and flexible parametric relative survival models seemed to be suitable in various scenarios.

Conclusion

Using extrapolation to estimate the loss of lifetime function requires careful consideration of the relative survival function outside the available follow-up period. We propose extensive sensitivity analyses when estimating the loss of lifetime function.

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0661-8) contains supplementary material, which is available to authorized users.

Tackling the tobacco epidemic in the Nordic countries and lower cancer incidence by 1/5 in a 30-year period-The effect of envisaged scenarios changing smoking prevalence

BACKGROUND

Tobacco smoking is a leading cause of cancer and the most preventable cause of cancer worldwide. The aim of this study was to quantify the proportion of the cancer burden in the Nordic countries linked to tobacco smoking and estimate the potential for cancer prevention by changes in smoking prevalence.

METHODS

The Prevent macro-simulation model was used, estimating the future number of cancer cases in the Nordic countries over a 30-year period (2016-2045), for 13 cancer sites, under different scenarios of changing smoking prevalence, and compared to the projected number of cases if constant prevalence prevailed.

RESULTS

A total of 430,000 cancer cases, of the 2.2 million expected for the 13 studied cancer sites, could be avoided in the Nordic countries over the 30-year period if smoking was eliminated from 2016 onwards. If prevalence of smoking is reduced to 5% by year 2030 and to 2% by 2040, 230,000 cancer cases could be avoided. The largest proportion of cancers can be avoided in Denmark, where smoking prevalence is the highest, and similar to the prevalence in many European countries.

CONCLUSION

A large amount of cancers could be avoided in the Nordic countries if smoking prevalence was reduced. The results from this study can be used to understand the potential impact and significance of primary prevention programmes targeted towards reducing the prevalence of tobacco smoking in the Nordic countries.

Mortality in treatment-resistant unipolar depression: A register-based cohort study in Sweden

BACKGROUND

The impact of treatment resistant depression (TRD) on mortality is not established.

METHODS

Using Swedish national registers, 118,774 patients between 18-69 years of age who had been prescribed an antidepressant and been diagnosed with depression in specialized care were identified. Patients with at least two additional treatment trials during the same depressive episode were classified as having TRD. Data on the covariates of sex, age, history of depression, self-harm, substance use disorders, and other psychiatric and somatic comorbidities was also used. Relative risks comparing TRD patients with other depressed patients were calculated as hazard ratios (HR) for all-cause mortality and for external and non-external causes of death, as well as excess mortality rate ratios (EMRR), with 95% confidence intervals (CI).

RESULTS

In total 15,013 patients (13%) were classified with TRD. Adjusted HR for all-cause mortality was 1.35 (95% CI 1.21-1.50). Mortality from external causes (including suicides and accidents) was markedly higher in TRD patients than in other depressed patients (HR 1.97; 1.69-2.29), while mortality from non-external causes was similar. The adjusted EMRR was 1.52 (1.31-1.76), highest among patients 18-29 years old (EMRR 2.03; 1.31-1.76) and patients without somatic comorbidity (EMRR 1.99; 1.63-2.43).

LIMITATIONS

Severity of depression and adherence to treatment were not available in the data.

CONCLUSIONS

Patients with TRD may have an increased all-cause mortality compared to other depressed patients, mainly for external causes of death. The relative mortality is highest among young and physically healthy patients.

Sunbed use 2007-2015 and skin cancer projections of campaign results 2007-2040 in the Danish population: repeated cross-sectional surveys

OBJECTIVE

To evaluate the effect of the Danish Sun Safety Campaign 2007-2015 on the prevalence of sunbed use and to model future effects on the skin cancer incidences 2007-2040.

DESIGN

The study has a repeated, cross-sectional design.

SETTING

Exposure to ultraviolet radiation is the main risk factor for skin cancer. Denmark has the highest prevalence of sunbed use reported and one of the highest incidences of skin cancer worldwide.

PARTICIPANTS

During 2007-2015, survey data were collected for 37 766 Danes, representative of the Danish population with regards to age, gender and region.

INTERVENTIONS

In 2007, an ongoing long-term antisunbed campaign was launched in Denmark.

PRIMARY AND SECONDARY OUTCOME MEASURES

Sunbed use was evaluated by annual cross-sectional surveys. Skin cancer incidence was modelled in the Prevent programme, using population projections, historic cancer incidence, sunbed use exposure and relative risk of sunbed use on melanoma.

RESULTS

The prevalence of recent sunbed use in Denmark was reduced from 32% and 18% to 13% and 8% for women and men, respectively. The campaigns results during 2007-2015 are estimated to reduce the number of skin cancer cases from more than 5000 (746malignant melanoma, 1562 SCC, 2673 BCC) totally during 2007-2040. Keeping the 2015 level of sunbed use constant by continued campaign pressure or introduction of structural interventions would potentially prevent more than 750 skin cancer cases annually in 2040 and 16 000 skin cancer cases in total during 2007-2040.

CONCLUSION

We have shown the value of prevention and of long-term planning in prevention campaigning. Sunbed use was reduced significantly during 2007-2015 and further reductions are possible by structural interventions. Consequently, significantly fewer skin cancer cases are anticipated during 2007-2040. The Danish Parliament has population support to enforce structural interventions to avoid a large burden of this disease.

Avoidable cancers in the Nordic countries-The impact of alcohol consumption

BACKGROUND

Alcohol consumption is an important and preventable cause of cancer. The aim of this study was to quantify the proportion of the cancer burden in the Nordic countries linked to alcohol and estimate the potential for cancer prevention by changes in alcohol consumption.

METHODS

Using the Prevent macro-simulation model, the number of cancer cases in the Nordic countries over a 30-year period (2016-2045) was modelled for six sites, under different scenarios of changing alcohol consumption, and compared to the projected number of cases if constant alcohol consumption prevailed. The studied sites were colorectal, post-menopausal breast, oral cavity and pharynx, liver, larynx as well as oesophageal squamous cell carcinoma. The alcohol consumption was based on the categories of non-drinkers/occasional drinkers, light drinkers (<=12.5 g alcohol per day), moderate drinkers (>12.5 and ≤ 50 g/day) and heavy drinkers (>50 g/day).

RESULTS

About 83,000 cancer cases could be avoided in the Nordic countries in a 30-year period if alcohol consumption was entirely eliminated, which is 5.5% of the expected number of cases for the six alcohol-related cancer types. With a 50% reduction in the proportion with moderate alcohol consumption by year 2025, 21,500 cancer cases could be avoided. The number of avoidable cases was highest for post-menopausal breast and colorectal cancer, but the percentage was highest for oesophageal squamous cell carcinoma.

CONCLUSION

The results from this study can be used to understand the potential impact and significance of primary prevention programmes targeted towards reducing the alcohol consumption in the Nordic countries.

Second malignancies in patients with myeloproliferative neoplasms: a population-based cohort study of 9379 patients

To determine the risk of a wide range of second malignancies in patients with myeloproliferative neoplasms (MPNs), we conducted a large population-based study and compared the results to matched controls. From national Swedish registers, 9379 patients with MPNs diagnosed between 1973 and 2009, and 35,682 matched controls were identified as well as information on second malignancies, with follow-up until 2010. Hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated using Cox regression and a flexible parametric model. There was a significantly increased risk of any non-hematologic cancer with HR of 1.6 (95% CI: 1.5-1.7). The HRs for non-melanoma skin cancer was 2.8 (2.4-3.3), kidney cancer 2.8 (2.0-4.0), brain cancer 2.8 (1.9-4.2), endocrine cancers 2.5 (1.6-3.8), malignant melanoma 1.9 (1.4-2.7), pancreas cancer 1.8 (1.2-2.6), lung cancer 1.7 (1.4-2.2), and head and neck cancer 1.7 (1.2-2.6). The HR of second malignancies was similar across all MPN subtypes, sex, and calendar periods of MPN diagnosis. The risk of developing a hematologic malignancy was also significantly increased; the HR for acute myeloid leukemia was 46.0 (32.6-64.9) and for lymphoma 2.6 (2.0-3.3). In conclusion, our study provides robust population-based support of an increased cancer risk in MPN patients.

Estimating the impact of a cancer diagnosis on life expectancy by socio-economic group for a range of cancer types in England

BACKGROUND

Differences in cancer survival exist across socio-economic groups for many cancer types. Standard metrics fail to show the overall impact for patients and the population.

METHODS

The available data consist of a population of ∼2.5 million patients and include all patients recorded as being diagnosed with melanoma, prostate, bladder, breast, colon, rectum, lung, ovarian and stomach cancers in England between 1998 and 2013. We estimated the average loss in expectation of life per patient in years and the proportion of life lost for a range of cancer types, separately by deprivation group. In addition, estimates for the total number of years lost due to each cancer were also obtained.

RESULTS

Lung and stomach cancers result in the highest overall loss for males and females in all deprivation groups in terms of both absolute life years lost and loss as a proportion of expected life remaining. Female lung cancer patients in the least- and most-deprived group lose 14.4 and 13.8 years on average, respectively, that is translated as 86.1% and 87.3% of their average expected life years remaining. Melanoma, prostate and breast cancers have the lowest overall loss. On the basis of the number of patients diagnosed in 2013, lung cancer results in the most life years lost in total followed by breast cancer. Melanoma and bladder cancer account for the lowest total life years lost.

CONCLUSIONS

There are wide differences in the impact of cancer on life expectancy across deprivation groups, and for most cancers the most affluent lose less years.

Waiting time for cancer treatment and mental health among patients with newly diagnosed esophageal or gastric cancer: a nationwide cohort study

Background

Except for overall survival, whether or not waiting time for treatment could influences other domains of cancer patients’ overall well-being is to a large extent unknown. Therefore, we performed this study to determine the effect of waiting time for cancer treatment on the mental health of patients with esophageal or gastric cancer.

Methods

Based on the Swedish National Quality Register for Esophageal and Gastric Cancers (NREV), we followed 7,080 patients diagnosed 2006–2012 from the time of treatment decision. Waiting time for treatment was defined as the interval between diagnosis and treatment decision, and was classified into quartiles. Mental disorders were identified by either clinical diagnosis through hospital visit or prescription of psychiatric medications. For patients without any mental disorder before treatment, the association between waiting time and subsequent onset of mental disorders was assessed by hazard ratios (HRs) with 95% confidence interval (CI), derived from multivariable-adjusted Cox model. For patients with a preexisting mental disorder, we compared the rate of psychiatric care by different waiting times, allowing for repeated events.

Results

Among 4,120 patients without any preexisting mental disorder, lower risk of new onset mental disorders was noted for patients with longer waiting times, i.e. 18–29 days (HR 0.86; 95% CI 0.74-1.00) and 30–60 days (HR 0.79; 95% CI 0.67-0.93) as compared with 9–17 days. Among 2,312 patients with preexisting mental disorders, longer waiting time was associated with more frequent psychiatric hospital care during the first year after treatment (37.5% higher rate per quartile increase in waiting time; p for trend = 0.0002). However, no such association was observed beyond one year nor for the prescription of psychiatric medications.

Conclusions

These data suggest that waiting time to treatment for esophageal or gastric cancer may have different mental health consequences for patients depending on their past psychiatric vulnerabilities. Our study sheds further light on the complexity of waiting time management, and calls for a comprehensive strategy that takes into account different domains of patient well-being in addition to the overall survival.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-3013-7) contains supplementary material, which is available to authorized users.

Life Expectancy of Patients With Chronic Myeloid Leukemia Approaches the Life Expectancy of the General Population

PURPOSE

A dramatic improvement in the survival of patients with chronic myeloid leukemia (CML) occurred after the introduction of imatinib mesylate, the first tyrosine kinase inhibitor (TKI). We assessed how these changes affected the life expectancy of patients with CML and life-years lost as a result of CML between 1973 and 2013 in Sweden.

MATERIALS AND METHODS

Patients recorded as having CML in the Swedish Cancer Registry from 1973 to 2013 were included in the study and followed until death, censorship, or end of follow-up. The life expectancy and loss in expectation of life were predicted from a flexible parametric relative survival model.

RESULTS

A total of 2,662 patients with CML were diagnosed between 1973 and 2013. Vast improvements in the life expectancy of these patients were seen over the study period; larger improvements were seen in the youngest ages. The great improvements in life expectancy translated into great reductions in the loss in expectation of life. Patients of all ages diagnosed in 2013 will, on average, lose < 3 life-years as a result of CML.

CONCLUSION

Imatinib mesylate and new TKIs along with allogeneic stem cell transplantation and other factors have contributed to the life expectancy in patients with CML approaching that of the general population today. This will be an important message to convey to patients to understand the impact of a CML diagnosis on their life. In addition, the increasing prevalence of patients with CML will have a great effect on future health care costs as long as continuous TKI treatment is required.

Life Expectancy of Patients With Chronic Myeloid Leukemia Approaches the Life Expectancy of the General Population

PURPOSE

A dramatic improvement in the survival of patients with chronic myeloid leukemia (CML) occurred after the introduction of imatinib mesylate, the first tyrosine kinase inhibitor (TKI). We assessed how these changes affected the life expectancy of patients with CML and life-years lost as a result of CML between 1973 and 2013 in Sweden.

MATERIALS AND METHODS

Patients recorded as having CML in the Swedish Cancer Registry from 1973 to 2013 were included in the study and followed until death, censorship, or end of follow-up. The life expectancy and loss in expectation of life were predicted from a flexible parametric relative survival model.

RESULTS

A total of 2,662 patients with CML were diagnosed between 1973 and 2013. Vast improvements in the life expectancy of these patients were seen over the study period; larger improvements were seen in the youngest ages. The great improvements in life expectancy translated into great reductions in the loss in expectation of life. Patients of all ages diagnosed in 2013 will, on average, lose < 3 life-years as a result of CML.

CONCLUSION

Imatinib mesylate and new TKIs along with allogeneic stem cell transplantation and other factors have contributed to the life expectancy in patients with CML approaching that of the general population today. This will be an important message to convey to patients to understand the impact of a CML diagnosis on their life. In addition, the increasing prevalence of patients with CML will have a great effect on future health care costs as long as continuous TKI treatment is required.

Joint modelling of longitudinal and survival data: incorporating delayed entry and an assessment of model misspecification

A now common goal in medical research is to investigate the inter-relationships between a repeatedly measured biomarker, measured with error, and the time to an event of interest. This form of question can be tackled with a joint longitudinal-survival model, with the most common approach combining a longitudinal mixed effects model with a proportional hazards survival model, where the models are linked through shared random effects. In this article, we look at incorporating delayed entry (left truncation), which has received relatively little attention. The extension to delayed entry requires a second set of numerical integration, beyond that required in a standard joint model. We therefore implement two sets of fully adaptive Gauss-Hermite quadrature with nested Gauss-Kronrod quadrature (to allow time-dependent association structures), conducted simultaneously, to evaluate the likelihood. We evaluate fully adaptive quadrature compared with previously proposed non-adaptive quadrature through a simulation study, showing substantial improvements, both in terms of minimising bias and reducing computation time. We further investigate, through simulation, the consequences of misspecifying the longitudinal trajectory and its impact on estimates of association. Our scenarios showed the current value association structure to be very robust, compared with the rate of change that we found to be highly sensitive showing that assuming a simpler trend when the truth is more complex can lead to substantial bias. With emphasis on flexible parametric approaches, we generalise previous models by proposing the use of polynomials or splines to capture the longitudinal trend and restricted cubic splines to model the baseline log hazard function. The methods are illustrated on a dataset of breast cancer patients, modelling mammographic density jointly with survival, where we show how to incorporate density measurements prior to the at-risk period, to make use of all the available information. User-friendly Stata software is provided.

The proportion cured of patients diagnosed with Stage III-IV cutaneous malignant melanoma in Sweden 1990-2007: A population-based study

The survival in cutaneous malignant melanoma (CMM) is highly dependent on the stage of the disease. Stage III-IV CMM patients are at high risk of relapse with a heterogeneous outcome, but not all experience excess mortality due to their disease. This group is referred to as the cure proportion representing the proportion of patients who experience the same mortality rate as the general population. The aim of this study was to estimate the cure proportion of patients diagnosed with Stage III-IV CMM in Sweden. From the population-based Swedish Melanoma Register, we included 856 patients diagnosed with primary Stage III-IV CMM, 1990-2007, followed-up through 2013. We used flexible parametric cure models to estimate cure proportions and median survival times (MSTs) of uncured by sex, age, tumor site, ulceration status (in Stage III patients) and disease stage. The standardized (over sex, age and site) cure proportion was lower in Stage IV CMMs (0.15, 95% CI 0.09-0.22) than non-ulcerated Stage III CMMs (0.48, 95% CI 0.41-0.55) with a statistically significant difference of 0.33 (95% CI = 0.24-0.41). Ulcerated Stage III CMMs had a cure proportion of 0.27 (95% CI 0.21-0.32) with a statistically significant difference compared to non-ulcerated Stage III CMMs (difference 0.21; 95% CI = 0.13-0.30). The standardized MST of uncured was approximately 9-10 months longer for non-ulcerated versus ulcerated Stage III CMMs. We could demonstrate a significantly better outcome in patients diagnosed with non-ulcerated Stage III CMMs compared to ulcerated Stage III CMMs and Stage IV disease after adjusting for age, sex and tumor site.

Risk and Cause of Death in Patients Diagnosed With Myeloproliferative Neoplasms in Sweden Between 1973 and 2005: A Population-Based Study

PURPOSE

Myeloproliferative neoplasms (MPNs) are associated with a shortened life expectancy. We assessed causes of death in patients with MPN and matched controls using both relative risks and absolute probabilities in the presence of competing risks.

PATIENTS AND METHODS

From Swedish registries, we identified 9,285 patients with MPN and 35,769 matched controls. A flexible parametric model was used to estimate cause-specific hazard ratios (HRs) of death and cumulative incidence functions, each with 95% CIs.

RESULTS

In patients with MPN, the HRs of death from hematologic malignancies and infections were 92.8 (95% CI, 70.0 to 123.1) and 2.7 (95% CI, 2.4 to 3.1), respectively. In patients age 70 to 79 years at diagnosis (the largest patient group), the HRs of death from cardiovascular and cerebrovascular disease were 1.5 (95% CI, 1.4 to 1.7) and 1.5 (95% CI, 1.3 to 1.8), respectively; all were statistically significantly elevated compared with those of controls. In the same age group, no difference was observed in the 10-year probability of death resulting from cardiovascular disease in patients with MPN versus controls (16.8% v 15.2%) or cerebrovascular disease (5.6% v 5.2%). In patients age 50 to 59 years at diagnosis, the 10-year probability of death resulting from cardiovascular and cerebrovascular disease was elevated, 4.2% versus 2.1% and 1.9% versus 0.4%, respectively. Survival in patients with MPN increased over time, mainly because of decreased probabilities of dying as a result of hematologic malignancies, infections, and, in young patients, cardiovascular disease.

CONCLUSION

Patients with MPN had an overall higher mortality rate than that of matched controls, primarily because of hematologic malignancy, infections, and vascular events in younger patients. Evidently, there is still a need for effective disease-modifying agents to improve patient outcomes.

The loss in expectation of life after colon cancer: a population-based study

Background

To demonstrate how assessment of life expectancy and loss in expectation of life can be used to address a wide range of research questions of public health interest pertaining to the prognosis of cancer patients.

Methods

We identified 135,092 cases of colon adenocarcinoma diagnosed during 1961–2011 from the population-based Swedish Cancer Register. Flexible parametric survival models for relative survival were used to estimate the life expectancy and the loss in expectation of life.

Results

The loss in expectation of life for males aged 55 at diagnosis was 13.5 years (95 % CI 13.2–13.8) in 1965 and 12.8 (12.4–13.3) in 2005. For males aged 85 the corresponding figures were 3.21 (3.15–3.28) and 2.10 (2.04–2.17). The pattern was similar for females, but slightly greater loss in expectation of life. The loss in expectation of life is reduced given survival up to a certain time point post diagnosis. Among patients diagnosed in 2011, 945 life years could potentially be saved if the colon cancer survival among males could be brought to the same level as for females.

Conclusion

Assessment of loss in expectation of life facilitates the understanding of the impact of cancer, both on individual and population level. Clear improvements in survival among colon cancer patients have led to a gain in life expectancy, partly due to a general increase in survival from all causes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1427-2) contains supplementary material, which is available to authorized users.