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

The combination of poly(ADP-ribose) polymerase inhibitor and statin inhibits the proliferation of human castration-resistant and taxane-resistant prostate cancer cells in vitro and in vivo

BACKGROUND

Olaparib exhibits antitumor effects in castration-resistant prostate cancer patients with germline mutations in DNA repair genes. We previously reported that simvastatin reduced the expression of DNA repair genes in PC-3 cells. The efficacy of combination therapy using olaparib and simvastatin as "BRCAness" in castration-resistant and taxane-resistant prostate cancers was evaluated in this study.

METHODS

PC-3, LNCaP, and 22Rv1 human prostate cancer cell lines were used to develop androgen-independent LNCaP cells (LNCaP-LA). mRNA and protein expression levels were evaluated by quantitative real-time polymerase chain reaction and western blot analysis, respectively. Cell viability was determined using the MTS assay and cell counts. All evaluations were performed on cells treated with simvastatin with or without olaparib.

RESULTS

The mRNA levels of BRCA1, BRCA2, RAD51, FANCD2, FANCG, FANCA, BARD1, RFC3, RFC4, and RFC5, which are known DNA repair genes, were downregulated by simvastatin in androgen-independent prostate cancer cells, such as PC-3, LNCaP-LA, and 22Rv1 cells. In contrast, the expression of all these genes remained unchanged in androgen-dependent LNCaP cells following treatment with simvastatin. Furthermore, simvastatin increased the expression of above stated genes in normal prostate stromal cells (PrSC). The reduction in BRCA1 and BRCA2 expression following siRNA transfection increased the cytocidal effects of Olaparib in PC-3 and LNCaP-LA cells. The combination of olaparib and simvastatin further inhibited cell proliferation compared to monotherapy with either drug in PC-3, 22Rv1, and LNCaP-LA cells but not in PrSC cells. In a 22Rv1-derived mouse xenograft model, the combination of olaparib and simvastatin enhanced the inhibition of cell proliferation. Moreover, we established a 22Rv1 cell line with acquired resistance to Cabazitaxel (22Rv1-CR). In 22Rv1-CR cells, simvastatin also decreased the expression of BRCA1, BRCA2, and FANCA, and the combination of olaparib and simvastatin further enhanced the inhibition of cell proliferation compared with treatment with either of the drugs alone.

CONCLUSIONS

Simvastatin altered the expression of several genes associated with DNA repair in castration-resistant and taxane-resistant prostate cancer cells. The combination of poly (ADP-ribose) polymerase inhibitors and drugs that decrease DNA repair gene expression can potentially affect castration-resistant and taxane-resistant prostate cancer growth.

Estimating cancer incidence attributable to physical inactivity in the United States

BACKGROUND

Previous estimates of the number of cancers attributable to physical inactivity in the United States have typically focused on only three malignancies (colon, endometrial, and postmenopausal breast cancer). Contemporary epidemiologic evidence suggests that physical inactivity could contribute to up to 15 types of cancer, and a dose-response effect has been demonstrated for 13 of these. This study estimated the number of cancers diagnosed in the United States in 2015 due to physical inactivity for these 13 sites.

METHODS

Data from the 2005 National Health Interview Survey were used to estimate physical activity prevalence and, with the assumption of a 10-year latency period, 2015 cancer incidence data from the National Program of Cancer Registries and Surveillance, Epidemiology, and End Results Incidence US Cancer Statistics Public Use Database.

RESULTS

The potential impact fraction was estimated to be 4.1%, which meant that 30,951 of 761,625 incident cancers at the 13 sites could have been prevented in the United States in 2015 if adults had increased physical activity by one category in 2005 (approximately 7.5 additional metabolic equivalent task hours per week [MET-h/week]). Theoretically, 85,415 of 761,625 incident cancers at the 13 sites (population attributable fraction, 11.2%) could have been prevented if all adults had achieved the highest level of physical activity (>30 MET-h/week).

CONCLUSIONS

When estimates are based on updated epidemiologic evidence regarding physical inactivity and cancer risk, substantially more cancers are attributable to physical inactivity than previously reported. A greater focus on physical activity promotion is warranted for cancer control in the United States.

Every tenth malignant solid tumor attributed to overweight and alcohol consumption: A population-based cohort study

BACKGROUND

Recent studies have shown that some four in ten cancers are attributable to a few key risk factors. The aim of this study was to estimate cohort-based population attributable fractions (PAFs) in Finland for potentially modifiable cancer risk factors.

METHODS

Data from eight health studies including 253,953 subjects with 29,802 incident malignant solid tumors were analysed using Bayesian multivariate regression model with multiplicative risk factor effects. We estimated the effects of smoking, excess body weight, alcohol consumption, physical activity, parity and education on cancer incidence and related PAFs by cancer site, accounting for competing mortality.

RESULTS

PAF for all cancer sites and exposures combined was 34% (95% credible interval 29%-39%) in men and 24% (19%-28%) in women. In men, 23% (21%-27%) and in women 8% (6%-9%) of all cancers were attributed to smoking. PAF related to excess body weight was 4% (2%-6%) in men and 5% (2%-7%) in women, to alcohol 7% (3%-10%) in men and 4% (0%-7%) in women, and to excess body weight and alcohol combined 10% (6%-15%) in men and 9% (4%-13%) in women.

CONCLUSION

Smoking was the most important factor contributing to cancer burden in Finnish men and women over the last 40 years. The contribution of excess body weight and alcohol consumption together outweighed the role of smoking in women. As the prevalence of overweight is expected to increase, more efficient public health measures supporting adherence to healthy weight are essential to reduce cancer burden.

Impact of changing the prevalence of smoking, alcohol consumption and overweight/obesity on cancer incidence in China from 2021 to 2050: a simulation modelling study

Background

Smoking, alcohol consumption and overweight/obesity are key cancer risk factors contributing to the cancer burden in China. We aimed to quantify the cancer burden in China associated with smoking, alcohol consumption and overweight/obesity, and estimate the potential effect for cancer prevention interventions under different scenarios.

Methods

We used a macro-simulation approach called Prevent Model to estimate for a 30-year study period (2021-2050) numbers and proportions of future avoidable cancer cases under different scenarios of reducing the prevalence of smoking, alcohol consumption and overweight/obesity in Chinese adults. Cancer incidence was predicted under three scenarios: elimination, ambitious target (between elimination and manageable target) and manageable target (from national policy or global action plan). Risk factor prevalence was obtained from China Chronic Disease and Risk Factor Surveillance, and cancer incidence data were derived from the China Cancer Registry Annual Report. Relative risks were obtained from several recent large-scale studies or high-quality meta-analysis. Population data were extracted from the China Population & Employment Statistical Yearbook, China Health Statistical Yearbook and World Population Prospects.

Findings

Estimates of the avoidable cancer burden varied with different scenarios. In the theoretical maximum intervention scenario, where the prevalence of smoking, alcohol consumption and overweight/obesity would be eliminated, 9.17% (males: 13.50%; females: 1.47%) of smoking-related cancer cases, 7.06% (males: 11.49%; females: 1.00%) of cancer cases related to alcohol consumption and 8.22% (males: 7.91%; females: 8.52%) of overweight/obesity-related cancer cases were estimated to be avoidable during 2021-2050. Other scenarios, with more moderate goals in the exposure prevalence of smoking, alcohol use and overweight/obesity were also found to be associated with substantial reductions in the future cancer burden.

Interpretation

Our results suggested that a substantial number of future cancer cases could be avoided in Chinese adults by reducing the prevalence of smoking, alcohol consumption and overweight/obesity.

Funding

National Science & Technology Fundamental Resources Investigation Program of China; Sanming Project of Medicine in Shenzhen.

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.

Updated fraction of cancer attributable to lifestyle and environmental factors in Denmark in 2018

Environmental exposures and avoidable risk factors account for a large proportion of cancer burden. Exposures and lifestyle vary over time and between populations, which calls for updated and population-specific quantification of how various avoidable risk factors influence cancer risk to plan and design rational and targeted prevention initiatives. The study considered 12 risk-factor groups categorized as class I carcinogens by IARC/WCRF. Exposure data was derived from national studies and surveys and were linked to cancer incidence in 2018 based on the nationwide Danish Cancer Registry. In 2018, 23,078 men and 21,196 women were diagnosed with cancer excluding non-melanoma skin cancer, in Denmark. Of these, 14,235 (32.2%) were estimated to be attributable to avoidable class I carcinogens. Tobacco smoking accounted for 14.6% of total cancers, followed by UV-radiation that accounted for 5.8%. Based on exposure data from 2008, one-third of the cancers in Denmark in 2018 are estimated to be caused by class I carcinogens with tobacco use being the main contributor followed by UV-radiation. Our results should be integrated with public health policies to effectively increase awareness and promote strategies to decrease risk factor exposures at population level.

Impact of reducing excess body weight and physical inactivity on cancer incidence in Germany from 2020 to 2050-a simulation model

BACKGROUND

Excess body weight and physical inactivity are key cancer risk factors contributing substantially to the cancer burden in Germany. We aimed to estimate the numbers and proportions of future cancer cases prevented under different scenarios of reducing the prevalence of excess body weight and physical inactivity in Germany.

METHODS

Based on a macro-simulation approach calculating age-, sex-, and cancer-site specific potential impact fractions, we estimated for a 30-year study period (2020-2050) numbers and proportions of cancer cases prevented under different scenarios of reducing excess body weight (overweight and obesity) and increasing levels of physical activity in the German population.

RESULTS

Estimates of the prevented cancer burden varied in the different scenarios. In the guideline exposure scenarios, in which the prevalence of excess body weight and insufficient levels of physical activity would be eliminated, 8.7% (men: 10.1%; women: 7.8%) of overweight/obesity-related cancer cases and 2.4% (men: 2.3%; women: 2.4%) of cancer cases related to physical inactivity were estimated to be prevented over a 30-year period. This translates to approximately 662,000 (men: 304,000; women: 358,000) and 129,000 (men: 42,000; women: 87,000) prevented cancer cases, respectively.

CONCLUSION

Our results illustrate that a substantial number of future cancer cases could be prevented in the German population by reducing excess body weight and physical inactivity.