A novel causal model for nasopharyngeal carcinoma

The development of nasopharyngeal carcinoma (NPC) and its unique geographic distribution have long been attributed to a combination of dietary intake of salt-preserved fish, inherited susceptibility, and early-life infection with the Epstein-Barr virus (EBV). New findings from our large, rigorously designed, population-based case-control study of NPC in southern China have enabled substantial revision of this causal model. Here, we briefly summarize these results and provide an updated model of the etiology of NPC. Our new research identifies two EBV genetic variants that may be causally involved in the majority of NPC in southern China, and suggests the rise of modern environmental co-factors accompanying cultural and economic transformation in NPC-endemic regions. These discoveries can be translated directly into clinical and public health advances, including improvement of indoor air quality and oral health, development of an EBV vaccine, enhanced screening strategies, and improved risk prediction. Greater understanding of the roles of environmental, genetic, and viral risk factors can reveal the extent to which these agents act independently or jointly on NPC development. The history of NPC research demonstrates how epidemiology can shed light on the interplay of genes, environment, and infections in carcinogenesis, and how this knowledge can be harnessed for cancer prevention and control.

Height as a mediator of sex differences in cancer risk

BACKGROUND

Globally, age-standardized incidence rates for most cancers at shared sites are substantially and consistently higher in men than in women. Differences in established risk factors are unable to account for much of the sex disparity. We hypothesized that variability in height may be important in explaining sex differences in cancer risk.

PATIENTS AND METHODS

We included 49 372 men from the Health Professionals Follow-up Study (1986-2014) and 115 612 women from the Nurses' Health Study (1980-2014). Height was reported at baseline and biennial questionnaires were used to collect information on cancer risk factors. We examined the association between sex and cancer incidence at shared anatomic sites using Cox proportional hazards models and performed mediation analysis to determine the percent of the association that was accounted for by height.

RESULTS

Over up to 34 years of follow-up, 21 307 incident cases of cancers at shared sites (7705 men, 13 602 women) were documented. After adjusting for major cancer risk factors, men had a 39% increased risk of shared cancers overall (hazard ratio = 1.39; 95% confidence interval = 1.33-1.45) of which 35% (95% confidence interval = 24-46) was mediated by height. The excess risk of cancer for men was also partially explained by height for several specific cancers (gastrointestinal, melanoma, kidney, brain, hematologic). Mediation by height tended to be stronger among never smokers or those who adhered to a healthy lifestyle, and for cancers with fewer known environmental risk factors.

CONCLUSIONS

Differences in height among men and women partially mediated the association between sex and cancer incidence at several shared sites. Hence, mechanisms underlying the relationship between height and cancer may be important determinants of sex disparities in cancer incidence.

Use of aspirin, other nonsteroidal anti-inflammatory drugs and acetaminophen and risk of endometrial cancer: the Epidemiology of Endometrial Cancer Consortium

BACKGROUND

Regular use of aspirin has been associated with a reduced risk of cancer at several sites but the data for endometrial cancer are conflicting. Evidence regarding use of other analgesics is limited.

PATIENTS AND METHODS

We pooled individual-level data from seven cohort and five case-control studies participating in the Epidemiology of Endometrial Cancer Consortium including 7120 women with endometrial cancer and 16 069 controls. For overall analyses, study-specific odds ratios (ORs) and 95% confidence intervals (CI) were estimated using logistic regression and combined using random-effects meta-analysis; for stratified analyses, we used mixed-effects logistic regression with study as a random effect.

RESULTS

At least weekly use of aspirin and non-aspirin nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with an approximately 15% reduced risk of endometrial cancer among both overweight and obese women (OR = 0.86 [95% CI 0.76-0.98] and 0.86 [95% CI 0.76-0.97], respectively, for aspirin; 0.87 [95% CI 0.76-1.00] and 0.84 [0.74-0.96], respectively, for non-aspirin NSAIDs). There was no association among women of normal weight (body mass index < 25 kg/m2, Pheterogeneity = 0.04 for aspirin, Pheterogeneity = 0.003 for NSAIDs). Among overweight and obese women, the inverse association with aspirin was stronger for use 2-6 times/week (OR = 0.81, 95% CI 0.68-0.96) than for daily use (0.91, 0.80-1.03), possibly because a high proportion of daily users use low-dose formulations. There was no clear association with use of acetaminophen.

CONCLUSION

Our pooled analysis provides further evidence that use of standard-dose aspirin or other NSAIDs may reduce risk of endometrial cancer among overweight and obese women.

First-onset mental disorders after cancer diagnosis and cancer-specific mortality: a nationwide cohort study

Background

The diagnosis of cancer is strongly associated with the risk of mental disorders even in patients with no previous history of mental disorders. Accumulating data suggest that mental distress may accelerate tumor progression. We hypothesized therefore that mental disorders after a cancer diagnosis may increase the risk of cancer-specific mortality.

Patients and methods

We conducted a nationwide cohort study including 244 261 cancer patients diagnosed in Sweden during 2004-2009 and followed them through 2010. Through the Swedish Patient Register, we obtained clinical diagnoses of all mental disorders and focused on mood-, anxiety-, and substance abuse disorders (ICD10: F10-F16, F18-F19, F32-F33, F40-F41, and F43-45) that are commonly diagnosed among patients with cancer. We further classified the studied mental disorders into first-onset or recurrent mental disorders. We used Cox regression to estimate multivariable hazard ratios (HRs) with 95% confidence intervals (CIs) as a measure of the association between mental disorders after cancer diagnosis and cancer-specific mortality, adjusting for age, sex, calendar period, educational level, cancer stage, and cancer type at diagnosis.

Results

After cancer diagnosis, 11 457 patients were diagnosed with mood-, anxiety-, and substance abuse disorders; of which 7236 were first-onset mental disorders. Patients with a first-onset mental disorder were at increased risk of cancer-specific mortality (HR: 1.82, 95% CI: 1.71-1.92) while patients with a recurrent mental disorder had much lower risk elevation (HR: 1.14, 95% CI: 1.05-1.24). The increased cancer-specific mortality by first-onset mental disorders was observed for almost all cancer sites/groups and the association was stronger for localized cancers (HR: 2.00, 95% CI: 1.73-2.31) than for advanced cancers (HR: 1.49, 95% CI: 1.32-1.69).

Conclusions

Patients with a first-onset common mood-, anxiety-, or substance abuse disorder after cancer diagnosis may be at increased risk of cancer-specific death.

Socioeconomic disparities in survival from childhood leukemia in the United States and globally: a meta-analysis

BACKGROUND

Despite advancements in the treatment of childhood leukemia, socioeconomic status (SES) may potentially affect disease prognosis. This study aims to evaluate whether SES is associated with survival from childhood leukemia.

METHODS

The US National Cancer Institute Surveillance, Epidemiology and End Results Program (SEER) 1973-2010 data were analyzed; thereafter, results were meta-analyzed along with those from survival (cohort) studies examining the association between SES indices and survival from childhood leukemia (end-of-search date: 31 March 2014). Random-effects models were used to calculate pooled effect estimates (relative risks, RRs); meta-regression was also used.

RESULTS

We included 29 studies yielding 28 804 acute lymphoblastic leukemia (ALL), 3208 acute myeloblastic leukemia (AML) and 27 650 'any' leukemia (denoting joint reporting of all subtypes) cases. According to individual-level composite SES indices, children from low SES suffered from nearly twofold higher death rates from ALL (pooled RR: 1.83, 95% confidence interval 1.00-3.34, based on four study arms); likewise, death RRs derived from an array of lower area-level SES indices ranged between 1.17 and 1.33 (based on 11 study arms). Importantly, the survival gap between higher and lower SES seemed wider in the United States, with considerably (by 20%-82%) increased RRs for death from ALL in lower SES. Regarding AML, poorer survival was evident only when area-level SES indices were used. Lastly, remoteness indices were not associated with survival from childhood leukemia.

CONCLUSION

Children with lower SES suffering childhood leukemia do not seem to equally enjoy the impressive recent survival gains. Special health policy strategies and increased awareness of health providers might minimize the effects of socioeconomic disparities.

Current status of screening for colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality. A well-defined precursor lesion (adenoma) and a long preclinical course make CRC a candidate for screening. This paper reviews the current evidence for the most important tests that are widely used or under development for population-based screening.

MATERIAL AND METHODS

In this narrative review, we scrutinized all papers we have been aware of, and carried out searches in PubMed and Cochrane library for relevant literature.

RESULTS

Two screening methods have been shown to reduce CRC mortality in randomised trials: repetitive faecal occult blood testing (FOBT) reduces CRC mortality by 16%; once-only flexible sigmoidoscopy (FS) by 28%. FS screening also reduces CRC incidence (by 18%), FOBT does not. Colonoscopy screening has a potentially larger effect on CRC incidence and mortality, but randomised trials are lacking. New screening methods are on the horizon but need to be tested in large clinical trials before implementation in population screening.

CONCLUSIONS

FS screening reduces CRC incidence and CRC mortality by removal of adenomas; FOBT reduces CRC mortality by early detection of cancer. Several other tests are available, but none has been evaluated in randomised trials. Screening strategies differ considerably across countries.

Development of a new method for monitoring prostate-specific antigen changes in men with localised prostate cancer: a comparison of observational cohorts

BACKGROUND

Prostate-specific antigen (PSA) measurements are increasingly used to monitor men with localised prostate cancer (PCa), but there is little consensus about the method to use.

OBJECTIVE

To apply age-specific predictions of PSA level (developed in men without cancer) to one cohort of men with clinically identified PCa and one cohort of men with PSA-detected PCa. We hypothesise that among men with clinically identified cancer, the annual increase in PSA level would be steeper than in men with PSA-detected cancer.

DESIGN, SETTING, AND PARTICIPANTS

The Scandinavian Prostate Cancer Group 4 (SPCG-4) cohort consisted of 321 men assigned to the watchful waiting arm of the SPCG-4 trial. The UK cohort consisted of 320 men with PSA-detected PCa in the Prostate testing for cancer and Treatment (ProtecT) study who opted for monitoring. Multilevel models describing changes in PSA level were fitted to the two cohorts, and average PSA level at age 50, change in PSA level with age, and predicted PSA values were derived.

MEASUREMENTS

PSA level.

RESULTS AND LIMITATIONS

In the SPCG-4 cohort, mean PSA at age 50 was similar to the cancer-free cohort but with a steeper yearly increase in PSA level (16.4% vs 4.0%). In the UK cohort, mean PSA level was higher than that in the cancer-free cohort (due to a PSA biopsy threshold of 3.0 ng/ml) but with a similar yearly increase in PSA level (4.1%). Predictions were less accurate for the SPCG-4 cohort (median difference between observed and predicted PSA level: -2.0 ng/ml; interquartile range [IQR]: -7.6-0.7 ng/ml) than for the UK cohort (median difference between observed and predicted PSA level: -0.8 ng/ml; IQR: -2.1-0.1 ng/ml).

CONCLUSIONS

In PSA-detected men, yearly change in PSA was similar to that in cancer-free men, whereas in men with symptomatic PCa, the yearly change in PSA level was considerably higher. Our method needs further evaluation but has promise for refining active monitoring protocols.

Benign prostatic hyperplasia and subsequent risk of bladder cancer

We evaluated the risk of bladder cancer in a cohort of 79,280 Swedish men hospitalised for benign prostatic hyperplasia (BPH), identified in the Swedish Inpatient Register between 1964 and 1983 and followed until 1989 via multiple record linkages with nationwide data on cancer registry, death and emigration. Standardised incidence ratios (SIRs), the ratios of the observed to the expected numbers of incident bladder cancers, were used to calculate the risk associated with BPH. The expected number was calculated by multiplying the number of person-years by the age-specific cancer incidence rates in Sweden for each 5-year age group and calendar year of observation. Analyses were stratified by BPH treatment, latency, calendar year and presence of genitourinary (GU) comorbid conditions. After excluding the first 3 years of follow-up after the index hospitalisation, we observed 506 incident bladder cancer cases during follow-up in the cohort. No overall increased risk of bladder cancer was apparent in our main analysis involving the entire BPH cohort. However, among BPH patients with transurethral resection of the prostate (TURP), there was an increased risk in all follow-up periods; SIRs of bladder cancer during years 4-6 of follow-up was 1.22 (95% confidence interval=1.02-1.46), 1.32 for 7-9 years of follow-up, and 1.47 for 10-26 years of follow-up. SIRs of bladder cancer among TURP-treated BPH patients were particularly elevated among those with comorbid conditions of the GU tract (e.g., stone, infection, etc.); 1.72, 1.74 and 2.01 for 4-6, 7-9, 10-26 years of follow-up, respectively, and also for those whose diagnoses occurred before 1975, when TURP was more likely to be performed by a urologist than a general practitioner: 1.87, 1.90 and 1.74, respectively. These findings suggest that BPH overall is not associated with bladder cancer risk. However, among men treated with TURP, particularly those with other comorbid GU tract conditions, risk of bladder cancer was elevated.

Preoperative serum levels of follicle stimulating hormone (FSH) and prognosis in invasive breast cancer

AIMS

We investigated the association between preoperative serum levels of follicle stimulating hormone (FSH) and the prognosis in women with invasive breast cancer.

METHODS

Serum levels of FSH were measured in 182 premenopausal and 581 peri- or postmenopausal women with invasive breast cancer. They were followed for a mean time of 84 months. The study endpoint was death from breast cancer (182 events). Analyses were stratified on menopausal status.

RESULTS

None of the estimates showed a statistically significant result. In both pre- and postmenopausal women there was a nominally higher probability of survival with a higher FSH level. Point estimates in multivariate analysis incorporating age, tumour diameter, axillary lymph status, estrogen and progesterone receptor content and year of treatment indicated a stronger association with FSH levels in premenopausal than postmenopausal women (relative hazard 0.63 or 0.85, respectively in the highest compared with the lowest quartile).

CONCLUSION

We did not find any statistically significant association between preoperative serum level of FSH and prognosis. Today, FSH is not a clinical target for intervention or a clinically useful prognostic factor and the results of clinical studies up to date can only be used for motivation of further experimental laboratory research.

Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

Risk of adenocarcinomas of the oesophagus and gastric cardia in patients hospitalized for asthma

In the first cohort study of the question we followed 92 986 (42 663 men and 50 323 women) adult patients hospitalized for asthma in Sweden from 1965 to 1994 for an average of 8.5 years to evaluate their risk of oesophageal and gastric cardia adenocarcinoma. Standardized incidence ratio (SIR) adjusted for gender, age and calendar year was used to estimate relative risk, using the Swedish nationwide cancer incidence rates as reference. Asthmatic patients overall had a moderately elevated risk for oesophageal adenocarcinoma (SIR = 1.5, 95% confidence interval CI, 0.9-2.5) and gastric cardia cancer (SIR = 1.4, 95% CI, 1.0-1.9). However, the excess risks were largely confined to asthmatic patients who also had a discharge record of gastro-oesophageal reflux (SIR = 7.5, 95% CI, 1.6-22.0 and SIR = 7.1, 95% CI, 3.1-14.0, respectively). No significant excess risk for oesophageal squamous-cell carcinoma or distal stomach cancer was observed. In conclusion, asthma is associated with a moderately elevated risk of developing oesophageal or gastric cardia adenocarcinoma. Special clinical vigilance vis-à-vis gastro-esophageal cancers seems unwarranted in asthmatic patients, but may be appropriate in those with clinically manifest gastro-oesophageal reflux.

Primary and secondary prevention in the reduction of cancer morbidity and mortality

Overall, cancer is a highly preventable disease. Indeed, modifiable external factors, discovered by epidemiological studies during the last 50 years, account for a majority of all cancer deaths. In this review, we discuss briefly these factors and their contribution to the current burden of cancer with an emphasis on the developed countries. Needless to say, tobacco smoking remains the largest contributor to the cancer landscape, whilst the contribution of poor diet and obesity may be equally important, but much more difficult to quantify. Our main goal was to assess what prevention of cancer has accomplished and might accomplish in the next two decades. Based on (necessarily crude) estimates, age-adjusted mortality rates from cancer in year 2000 had been reduced by approximately 13% due to primary prevention and an additional 6% due to the combined effect of early diagnosis and screening (secondary prevention). According to a realistic goal for the year 2020, a further 29% reduction might be achieved by primary, and 4% by secondary prevention. The main contribution to such accomplishments would be a reduction in tobacco smoking, improvements in diet--including reduced alcohol intake--and arrest of the obesity epidemic, in part through increased physical exercise. Rather than being granted, these goals require great effort and major commitment from all those who share responsibility for public health.

The risk of liver and bile duct cancer in patients with chronic viral hepatitis, alcoholism, or cirrhosis

No prospective study has analyzed simultaneously chronic viral hepatitis and alcoholism as risk factors for liver carcinogenesis, while taking into consideration the role of cirrhosis. Nor has the risk for hepatocellular carcinoma among patients with chronic viral hepatitis been prospectively evaluated in a low-risk Western population. Last, the relationship between hepatocellular carcinoma risk factors and bile duct cancer remains to be clarified. We analyzed prospectively the risk for primary liver and extrahepatic biliary tract cancer among 186,395 patients hospitalized with either chronic viral hepatitis, alcoholism, cirrhosis, or any combination of these conditions through linkages between national Swedish registers. Compared with the general population, the relative risk of hepatocellular carcinoma was 34.4 for chronic viral hepatitis alone, 2.4 for alcoholism alone, and 40.7 for cirrhosis alone. Among patients with combinations of these risk conditions, the relative risk of hepatocellular carcinoma was 27.3 for chronic viral hepatitis and alcoholism, 118.5 for chronic viral hepatitis and cirrhosis, 22.4 for alcoholism and cirrhosis, and 171.4 for all 3 conditions. We found limited evidence for an excess risk of intrahepatic, but not for extrahepatic, biliary duct cancer. Cirrhosis amplifies the risk of hepatocellular carcinoma among patients with chronic viral hepatitis, but it is not a prerequisite for liver carcinogenesis. In contrast, cirrhosis may be a necessary intermediate for the development of hepatocellular carcinoma among alcoholics.

Breast cancer risk in male alcoholics in Sweden

OBJECTIVE

To investigate the association between alcoholism and risk of male breast cancer.

METHODS

We conducted a retrospective population-based cohort study in Sweden of men diagnosed with alcoholism between 1965 and 1995. The cohort was followed up through interlinkages with nationwide registries (the national cancer registry, immigration registry, causes of death registry, and population registry), using the national registration numbers. Standardized incidence ratios (SIRs), calculated using the Swedish national cancer incidence rate as reference, were used as estimates of relative risks.

RESULTS

A total of 145,811 men were enrolled into the cohort, contributing 1,499,504 person-years of follow-up. Sixteen incident breast cancer cases were identified, and the mean age at diagnosis was 68 years. We excluded the first year of follow-up (cases and person-years) from the analysis to avoid detection bias. The overall SIR (excluding the first year of follow-up) was 1.1 (95% CI 0.6-2.0). Although based on small numbers we found no indication of a differential SIR according to duration of follow-up, age at cohort enrolment, or age at follow-up (attained age or age at cancer diagnosis).

CONCLUSION

The observed associations are not compatible with an increase in breast cancer risk among male alcoholics.

Risk of cancers of the lung, head and neck in patients hospitalized for alcoholism in Sweden

Alcoholic patients are at increased risk of cancers of the head and neck but little information is available on the magnitude of the risk for specific sites and for different histological types. We followed 182 667 patients with a hospital discharge diagnosis of alcoholism during 1965-1994, for an average of 10.2 years. We compared their incidence of site- and histological type-specific cancers of the oral cavity, pharynx, larynx and lung with that of the national population. The standardized incidence ratio (SIR) of cancer of the oral cavity and pharynx was 5.33 (95% confidence interval [CI] 5.04-5.64, based on 1207 cases). The SIRs of laryngeal and lung cancer were 4.21 (95% Cl 3.78-4.68, 347 cases) and 2.40 (2.29-2.51, 1880 cases), respectively. The SIR was highest for cancers of the hypopharynx, floor of the mouth, mesopharynx and base of the tongue. The relative excess of lung cancer was similar for squamous cell carcinoma and adenocarcinoma. Low age at first hospitalization was associated with higher SIRs for all sites under study. 25 years after first hospitalization for alcoholism, the cumulative probability of developing a lung cancer was in the order of 5%, for oral and pharyngeal cancer it was 2.5%, and for oesophageal or laryngeal cancer 1% each. Our study shows that the risk of head and neck cancer among heavy drinkers is highest for sites in direct contact with alcohol. The high risk of head and neck neoplasms may justify specific medical attention.

Attitudes to screening for cervical cancer: a population-based study in Sweden

OBJECTIVES

To investigate how attitudes and beliefs about Pap smear screening affect women's choice to participate in organized or opportunistic screening.

METHODS

Telephone interviews were conducted with 430 (69.0%) non-attenders and 514 (80.7%) attenders to Pap smear screening, sampled from a population-based database. The interviews were conducted during 1998 in Uppsala County, Sweden.

MAIN OUTCOME MEASURE

odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Non-attendance was negatively associated with perceived severity of cervical cancer compared to other malignancies (OR = 1.9, 95% CI 1.1-3.4) as well as with satisfactory benefits (OR = 0.7, 95% CI 0.6-0.8), but positively associated with time-consuming and economical barriers (OR = 1.2, 95% CI 1.1-1.5 and OR = 1.7, 95% CI 1.2-2.5, respectively). Non-attendance was also negatively associated with anxiety, but was of borderline significance (OR = 0.9, 95% CI 0.8-1.0). The results were strengthened with increasing time since last smear or if self-reported attendance status was used instead of true attendance. Non-attenders kept holding harder to their preferences than did attenders, stating they would not participate if their preferences were not met.

CONCLUSIONS

Important differences in attitudes and beliefs exist between non-attenders and attenders in Pap smear screening. Rather than being emotional, the main barriers are either practical or rooted in misunderstandings and lack of relevant information. These insights offer opportunities to increase attendance rates considerably.

Alcoholism and risk for cancer of the cervix uteri, vagina, and vulva

We conducted a population-based cohort study to analyze the risk of developing cancers of the female genitals among 36,856 patients with a hospital discharge diagnosis of alcoholism (ICD-7: 307, 322; ICD-8: 291, 303; ICD-9: 291, 303, 305A) in Sweden between 1965 and 1995. The follow-up was done by linkages of national registries. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were computed based on nationwide specific cancer rates. The first year of follow-up was excluded from all analyses to minimize the impact of selection bias. We found that alcoholic women had excess risks for in situ cervical cancer (SIR, 1.7; 95% CI, 1.6-1.9), for invasive cervical cancer (SIR, 2.9; 95% CI, 2.4-3.5), and for cancer of the vagina (SIR, 4.6; 95% CI, 2.2-8.5) but not for cancer of the vulva (SIR, 1.0; 95% CI, 0.4-2.0). The fact that alcoholics had an excess risk also for the in situ cancer suggests that the observed excess in invasive cervical cancer may not only be attributable to less use of Pap smear screening among them. The alcoholic women may be at higher risk for the progression from human papillomavirus infection to a malignant lesion for lifestyle-related reasons (promiscuity, smoking, use of contraceptive hormones, and dietary deficiencies). We conclude that alcoholic women are at high risk for in situ and invasive cervical cancer and for cancer of the vagina.

Alcoholism and risk for endometrial cancer

Endogenous estrogens increase the risk of endometrial cancer and are also elevated among women with high alcoholic intake. It is incompletely known, however, whether alcohol intake in general and alcohol abuse in particular increases risk for endometrial cancer. We thus analyzed prospectively the risk for endometrial cancer among 36,856 women hospitalized with alcoholism between 1965 and 1994 through linkages between several national Swedish registers. Compared with the general population, women who were alcoholics had an overall 24% lower risk of developing endometrial cancer, a finding challenging our a priori hypothesis. However, among women below the age of 50 years at follow-up, the mean age of menopause among Swedish women, the risk was 70% higher, whereas the risk among women aged 50 years or more at follow-up was 40% lower compared with the general population. Hence, the effect of alcoholism on endometrial cancer appears to be age dependent.

[Prevention and early diagnosis of cancer. What do we know? What do we think? Reports from the Lakardagarna in Orebro]

Läkardagarna (physician days) in Orebro is an annual course arranged by the Orebro Society of Medicine in collaboration with The Swedish Society of Medicine. In the year 2000 the title was "Prevention and early diagnosis of cancer. What do we know? What do we believe? What do we do?" With general practitioners as the target audience, the course covered basic biological science, risk factors, screening, ethical questions and the general practitioner's dilemma. This article reviews four selected contributions: 1) What is cancer? 2) Possible importance of the fetal stage for later risk of cancer; 3) Infections as a cause of cancer; and 4) Screening for cancer.

Reasons women do not attend screening for cervical cancer: a population-based study in Sweden

BACKGROUND

With an improved compliance with screening a larger reduction of cervical cancer incidence would be within reach. We aimed at investigating why certain women do not attend Pap smear screening and at validating the reliability of self-reported screening.

METHODS

In 1998 in the county of Uppsala, Sweden, information was collected through telephone interviews with 430 nonattendees and 514 attendees to Pap smear screening, who were all sampled from a population-based database. The women's recall of attendance was validated against the database. The main outcome measures used were odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Non-attendance was positively associated with nonuse of oral contraceptives (OR = 3.56, 95% CI 2.18-5.83), seeing different gynecologists (OR = 1.90, 95% CI 1.34-2.70), and seeing a physician very often (OR = 3.12, 95% CI 1.45-6.70) or not at all (OR = 1.78, 95% CI 1.09-2.90). Frequent condom use (OR = 1.88, 95% CI 1.02-3.47), living in rural/semirural areas (OR = 1.55, 95% CI 1.07-2.21), and not knowing the recommended screening interval (OR = 2.16, 95% CI 1.20-3.89) were all associated with nonattendance, whereas socioeconomic status was not, when tested in a multivariate model. Among the nonattendees, 57% underestimated the time lapse since last smear.

CONCLUSIONS

Seeing a gynecologist on a regular basis and information guiding women to have a Pap smear on their own initiative are important factors for recurrent screening. Therefore, information should be given to all women about the purpose and benefits of Pap smear testing. Self-reports on screening should be treated with caution.

The role of gene-environment interaction in the aetiology of human cancer: examples from cancers of the large bowel, lung and breast

It has become increasingly clear that cancer can be considered neither purely genetic nor purely environmental. A relatively new area of cancer research has focused on the interaction between genes and environment in the same causal mechanism. Primary candidates for gene-environment interaction studies have been genes that encode enzymes involved in the metabolism of established cancer risk factors. There are common variant forms of these genes (polymorphisms), which may alter metabolism and increase or decrease exposure to carcinogens, thus impacting the risk of cancer. We present an overview of enzymes involved in carcinogen metabolism, present epidemiological tools to evaluate gene-environment interactions, and provide examples from cancers of the breast, lung and large bowel.

Types of dietary fat and breast cancer: a pooled analysis of cohort studies

Recently, there has been interest in whether intakes of specific types of fat are associated with breast cancer risk independently of other types of fat, but results have been inconsistent. We identified 8 prospective studies that met predefined criteria and analyzed their primary data using a standardized approach. Holding total energy intake constant, we calculated relative risks for increments of 5% of energy for each type of fat compared with an equivalent amount of energy from carbohydrates or from other types of fat. We combined study-specific relative risks using a random effects model. In the pooled database, 7,329 incident invasive breast cancer cases occurred among 351,821 women. The pooled relative risks (95% confidence intervals [CI]) for an increment of 5% of energy were 1.09 (1.00-1.19) for saturated, 0.93 (0.84-1.03) for monounsaturated and 1.05 (0.96-1.16) for polyunsaturated fat compared with equivalent energy intake from carbohydrates. For a 5% of energy increment, the relative risks were 1.18 (95% CI 0.99-1.42) for substituting saturated for monounsaturated fat, 0.98 (95% CI 0.85-1.12) for substituting saturated for polyunsaturated fat and 0.87 (95% CI 0.73-1.02) for substituting monounsaturated for polyunsaturated fat. No associations were observed for animal or vegetable fat intakes. These associations were not modified by menopausal status. These data are suggestive of only a weak positive association with substitution of saturated fat for carbohydrate consumption; none of the other types of fat examined was significantly associated with breast cancer risk relative to an equivalent reduction in carbohydrate consumption.

Overweight as an avoidable cause of cancer in Europe

There is growing evidence that excess body weight increases the risk of cancer at several sites, including kidney, endometrium, colon, prostate, gallbladder and breast in post-menopausal women. The proportion of all cancers attributable to overweight has, however, never been systematically estimated. We reviewed the epidemiological literature and quantitatively summarised, by meta-analysis, the relationship between excess weight and the risk of developing cancer at the 6 sites listed above. Estimates were then combined with sex-specific estimates of the prevalence of overweight [body mass index (BMI) 25-29 kg/m(2)] and obesity (BMI > or = 30 kg/m(2)) in each country in the European Union to obtain the proportion of cancers attributable to excess weight. Overall, excess body mass accounts for 5% of all cancers in the European Union, 3% in men and 6% in women, corresponding to 27,000 male and 45,000 female cancer cases yearly. The attributable proportion varied, in men, between 2.1% for Greece and 4.9% for Germany and, in women, between 3.9% for Denmark and 8.8% for Spain. The highest attributable proportions were obtained for cancers of the endometrium (39%), kidney (25% in both sexes) and gallbladder (25% in men and 24% in women). The largest number of attributable cases was for colon cancer (21,500 annual cases), followed by endometrium (14,000 cases) and breast (12,800 cases). Some 36,000 cases could be avoided by halving the prevalence of overweight and obese people in Europe.

Pre-operative oestradiol levels - relation to survival in breast cancer

AIMS

There are clinical observations that operation during the luteal phase of the menstrual cycle (with high oestradiol levels) may positively influence prognosis in breast cancer. However, few studies have information on plasma levels of hormones pre-operatively.

METHODS

We studied 774 women treated for breast cancer where plasma levels of oestradiol had been measured 1-2 days pre-operatively. Date and cause of death were ascertained from the files of the Swedish Cancer Register and 5434 person-years were observed. The endpoint was death with breast cancer as the underlying cause (n=41 and n=158 in the pre- and post-menopausal group, respectively).

RESULTS

In life-table analyses, only pre-menopausal patients with oestradiol 500 pmol/l and above had a tendency (not statistically significant) for better survival. Multivariate Cox models with oestradiol modelled in continuous form yielded relative hazards (RH) close to unity in all women and in strata according to menopausal status.

CONCLUSIONS

When oestradiol was analysed in categorized form, only women with the highest levels had a tendency for improved prognosis (RH around 0.7; not statistically significant). Moreover, this pattern was not apparent for pre-menopausal women. Our findings contradict the notion that the pre-operative oestradiol level is independently associated with breast cancer prognosis.

Intake of fruits and vegetables and risk of breast cancer: a pooled analysis of cohort studies

CONTEXT

Some epidemiologic studies suggest that elevated fruit and vegetable consumption is associated with a reduced risk of breast cancer. However, most have been case-control studies in which recall and selection bias may influence the results. Additionally, publication bias may have influenced the literature on associations for specific fruit and vegetable subgroups.

OBJECTIVE

To examine the association between breast cancer and total and specific fruit and vegetable group intakes using standardized exposure definitions.

DATA SOURCES/STUDY SELECTION

Eight prospective studies that had at least 200 incident breast cancer cases, assessed usual dietary intake, and completed a validation study of the diet assessment method or a closely related instrument were included in these analyses.

DATA EXTRACTION

Using the primary data from each of the studies, we calculated study-specific relative risks (RRs) that were combined using a random-effects model.

DATA SYNTHESIS

The studies included 7377 incident invasive breast cancer cases occurring among 351 825 women whose diet was analyzed at baseline. For comparisons of the highest vs lowest quartiles of intake, weak, nonsignificant associations were observed for total fruits (pooled multivariate RR, 0.93; 95% confidence interval [CI], 0.86-1.00; P for trend =.08), total vegetables (RR, 0.96; 95% CI, 0.89-1.04; P for trend =.54), and total fruits and vegetables (RR, 0.93; 95% CI, 0.86-1.00; P for trend =.12). No additional benefit was apparent in comparisons of the highest and lowest deciles of intake. No associations were observed for green leafy vegetables, 8 botanical groups, and 17 specific fruits and vegetables.

CONCLUSION

These results suggest that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk.

Overweight as an avoidable cause of cancer in Europe

There is growing evidence that excess body weight increases the risk of cancer at several sites, including kidney, endometrium, colon, prostate, gallbladder and breast in post-menopausal women. The proportion of all cancers attributable to overweight has, however, never been systematically estimated. We reviewed the epidemiological literature and quantitatively summarised, by meta-analysis, the relationship between excess weight and the risk of developing cancer at the 6 sites listed above. Estimates were then combined with sex-specific estimates of the prevalence of overweight [body mass index (BMI) 25-29 kg/m(2)] and obesity (BMI > or = 30 kg/m(2)) in each country in the European Union to obtain the proportion of cancers attributable to excess weight. Overall, excess body mass accounts for 5% of all cancers in the European Union, 3% in men and 6% in women, corresponding to 27,000 male and 45,000 female cancer cases yearly. The attributable proportion varied, in men, between 2.1% for Greece and 4.9% for Germany and, in women, between 3.9% for Denmark and 8.8% for Spain. The highest attributable proportions were obtained for cancers of the endometrium (39%), kidney (25% in both sexes) and gallbladder (25% in men and 24% in women). The largest number of attributable cases was for colon cancer (21,500 annual cases), followed by endometrium (14,000 cases) and breast (12,800 cases). Some 36,000 cases could be avoided by halving the prevalence of overweight and obese people in Europe.

Incidence of ovarian cancer among alcoholic women: a cohort study in Sweden

Linkage of nationwide databases in Sweden allowed us to evaluate the incidence of ovarian cancer among 36,856 women diagnosed with alcoholism between 1965 and 1994. Mean duration of follow-up was 9.6 years, for a total of 317,518 person-years at risk. The expected number of cases of ovarian cancer was calculated by multiplying the number of person-years by 5-year age group and calendar year-specific incidence rates of ovarian cancer in Sweden. The effect measure was the standardized incidence ratio (SIR), with 95% confidence intervals (CIs). Our results indicate an overall deficit of cases of ovarian cancer of about 14% among women with a diagnosis of alcoholism. This deficit is particularly strong and statistically significant among alcoholic women younger than 60 years (SIR = 0.76, 95% CI 0.58-1.00). This deficit is compatible with the reported reduction of gonadotrophin levels among alcoholic women younger than 60 years and with the hypothesis invoking these gonadotrophins in the etiology of ovarian cancer.

Serum concentrations of organochlorines in men: a search for markers of exposure

Analysis of single marker substances in serum could provide cost-effective assessment of human exposure to complex mixtures of organochlorines. We studied the serum concentrations of 10 polychlorinated biphenyl (PCB) congeners and 11 chlorinated pesticides and some of their metabolites in samples collected from 120 Swedish men (mean age 63 years, range 40-74 years) from the general Swedish population. The median concentrations of individual PCB congeners increased in the order PCB 52 < PCB 101 < or = PCB28 < PCB 105 < PCB 167 < PCB 156 < PCB 118 < PCB 138 < PCB 180 < PCB 153. The concentrations of o,p'-DDT, o,p'-DDE, p,p'-DDD, alpha-HCH and gamma-HCH were in most cases below the quantification limit (2-4 ng/g lipid). Among the other chlorinated pesticides the median concentration increased in the order oxychlordane (12 ng/g lipid) < p,p'-DDT < trans-nonachlor < beta-HCH < HCB < p,p'-DDE (586 ng/g lipid). The observed concentrations of PCB and chlorinated pesticides were in the same range as those found in similar groups of men from Sweden and Norway, but lower than those found in male populations with recent occupational exposure or high environmental exposure. Strong relationships were found between the concentrations of single mono- and di-ortho PCB congeners and groups of PCB congeners in serum. In our group of men PCB 153 was a good marker substance for the concentration of sigma PCB and sigma di-ortho PCB concentrations in serum. Moreover, among the mono-ortho PCB congeners analyzed, PCB 156 could be used as a marker for the sigma mono-ortho PCB TEQ concentrations in serum in the studied group. No useful marker substances were found among DDT compounds and other chlorinated pesticides and metabolites, except for trans-nonachlor which predicted the concentration of the metabolite oxychlordane fairly well.

Can measurements of IGF-1 and IGFBP-3 improve the sensitivity of prostate-cancer screening?

Further well designed studies are urgently needed to clarify if use of prostate-specific antigen (PSA) as a diagnostic test for prostate cancer can be improved by incorporating measurements of serum insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding-protein 3 (IGFBP-3), and if these measurements might also identify men at higher risk.

A prospective study showing long-term infection with human papillomavirus 16 before the development of cervical carcinoma in situ

Human papillomavirus 16 (HPV16) is a predominant cause of cervical neoplasia. However, no population-based study with long-term follow-up has clarified the temporal relationship between HPV16 infection and occurrence of carcinoma in situ, or the importance of recurrent or persistent infection. This nested case-control study was carried out in a population-based cohort of women participating in cytological screening whose initial smear, taken in 1969-1995, was normal. During up to 26 years of follow-up, carcinoma in situ was diagnosed in 484 eligible women. Archival smears from these women were compared with smears from 619 individually matched controls. After DNA extraction, a highly sensitive PCR system was used to detect HPV16. Among case women, the prevalence of HPV16 positivity was 56% at the time of diagnosis. The relative risk of cervical carcinoma in situ increased from 3.6 (95% confidence interval, 1.2-11.0) 13 years before diagnosis to 11.1 (95% confidence interval, 5.5-22.2) 1 year before diagnosis. Having a positive smear at entry to the cohort increased risk >5-fold, whereas having persistent infection with HPV in two subsequent smears increased risk 30-fold. We estimated that among HPV16-positive women, the median incubation period from infection to carcinoma in situ was 7-12 years. We conclude that evidence of persistent and/or recurrent infection is associated with a drastically higher risk of cervical carcinoma in situ than occasional infection with HPV16.

Infections as a major preventable cause of human cancer

Infections may be responsible for over 15% of all malignancies worldwide. Important mechanisms by which infectious agents may induce carcinogenesis include the production of chronic inflammation, the transformation of cells by insertion of oncogenes and inhibition of tumour suppressors, and the induction of immunosuppression. Common characteristics shared by infectious agents linked to malignancies are that they are persistent in the host, often highly prevalent in the host population and induce cancer after a long latency. The associations between a selection of infectious agents and malignancies are covered in detail.

Alcohol and breast cancer risk: the alcoholism paradox

A population-based cohort study of 36 856 women diagnosed with alcoholism in Sweden between 1965 and 1995 found that alcoholic women had only a small 15% increase in breast-cancer incidence compared to the general female population. It is therefore apparent, contrary to expectation, that alcoholism does not increase breast-cancer risk in proportion to presumed ethanol intake.

Physical activity and postmenopausal endometrial cancer risk (Sweden)

OBJECTIVES

To examine the hypothesis that sedentary women have an increased risk of endometrial cancer compared to physically active women.

METHODS

This is a population-based case-control study in the entire Swedish female population aged 50-74 years in 1994-1995. We obtained self-reported information on leisure-time physical activity during childhood, at ages 18-30, and recently from 709 incident case women with endometrial cancer and 3368 population controls. Occupational physical activity was estimated through record linkage to the Swedish census data from 1960, 1970, 1980, and 1990. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for different activity levels by multivariate logistic regression, taking into account potential confounders.

RESULTS

Comparing lowest to highest (reference) levels of physical exercise, we observed statistically significant associations with risk of endometrial cancer for leisure-time activity at age 18-30 years (multivariate OR = 1.4; 95% CI = 1.0-1.8; p for trend 0.01) and in recent years (multivariate OR = 1.3; 95% CI = 1.0-1.7; p for trend 0.01). We found similar associations comparing lowest to highest (reference) levels of occupational activity assessed at the censuses in 1980 (multivariate OR = 1.4; 95% CI = 1.0-1.9; p for trend 0.03) and 1990 (multivariate OR = 1.3; 95% CI = 0.9-1.9, p for trend 0.05), but a less consistent association with censuses in 1960 and 1970. The increased risk associated with low level of occupational physical activity was confined to women who were not obese and to women who were smokers.

CONCLUSION

Our data, in conjunction with past epidemiological studies, indicate that both occupational and leisure-time physical activity may reduce the risk for postmenopausal endometrial cancer.

Pooled analysis of prospective cohort studies on height, weight, and breast cancer risk

The association between anthropometric indices and the risk of breast cancer was analyzed using pooled data from seven prospective cohort studies. Together, these cohorts comprise 337,819 women and 4,385 incident invasive breast cancer cases. In multivariate analyses controlling for reproductive, dietary, and other risk factors, the pooled relative risk (RR) of breast cancer per height increment of 5 cm was 1.02 (95% confidence interval (CI): 0.96, 1.10) in premenopausal women and 1.07 (95% CI: 1.03, 1.12) in postmenopausal women. Body mass index (BMI) showed significant inverse and positive associations with breast cancer among pre- and postmenopausal women, respectively; these associations were nonlinear. Compared with premenopausal women with a BMI of less than 21 kg/m2, women with a BMI exceeding 31 kg/m2 had an RR of 0.54 (95% CI: 0.34, 0.85). In postmenopausal women, the RRs did not increase further when BMI exceeded 28 kg/m2; the RR for these women was 1.26 (95% CI: 1.09, 1.46). The authors found little evidence for interaction with other breast cancer risk factors. Their data indicate that height is an independent risk factor for postmenopausal breast cancer; in premenopausal women, this relation is less clear. The association between BMI and breast cancer varies by menopausal status. Weight control may reduce the risk among postmenopausal women.

Infections as a major preventable cause of human cancer

Infections may be responsible for over 15% of all malignancies worldwide. Important mechanisms by which infectious agents may induce carcinogenesis include the production of chronic inflammation, the transformation of cells by insertion of oncogenes and inhibition of tumour suppressors, and the induction of immunosuppression. Common characteristics shared by infectious agents linked to malignancies are that they are persistent in the host, often highly prevalent in the host population and induce cancer after a long latency. The associations between a selection of infectious agents and malignancies are covered in detail.

Association between medications that relax the lower esophageal sphincter and risk for esophageal adenocarcinoma

BACKGROUND

The incidence of esophageal adenocarcinoma is increasing rapidly. Gastroesophageal reflux is a strong risk factor for this disease. The increase in incidence of esophageal adenocarcinoma coincided with the introduction of medications that promote reflux by relaxing the lower esophageal sphincter (LES), such as nitroglycerin, anticholinergics, beta-adrenergic agonists, aminophyllines, and benzodiazepines.

OBJECTIVE

To test the possible association between use of LES-relaxing medications and risk for adenocarcinoma of the esophagus and gastric cardia.

DESIGN

A nationwide population-based case-control study with in-person interviews.

SETTING

Sweden, 1995 through 1997.

PATIENTS

189 patients with newly diagnosed esophageal adenocarcinoma, 262 with adenocarcinoma of the gastric cardia, and 167 with esophageal squamous-cell carcinoma were compared with 820 population-based controls.

MEASUREMENTS

Estimated incidence rate ratios, calculated by using multivariate logistic regression from case-control data with adjustment for potential confounding.

RESULTS

Past use of LES-relaxing drugs was positively associated with risk for esophageal adenocarcinoma. Among daily, long-term users (>5 years) of LES-relaxing drugs, the estimated incidence rate ratio was 3.8 (95% CI, 2.2 to 6.4) compared with persons who had never used these drugs. Drugs of all classes contributed to the increased risk, but the association was particularly strong for anticholinergics. Short-term use of other types of LES-relaxing drugs did not seem to be strongly associated with risk. The association almost disappeared after adjustment for reflux symptoms, indicating that promotion of reflux is the link between use of LES-relaxing drugs and esophageal adenocarcinoma. If 15,490 men in any age group take LES-relaxing drugs daily for 5 years, 1 additional case of adenocarcinoma would be expected (number needed to treat for harm); in men older than 60 years of age, the number needed to treat for harm is 5,570. Assuming a causal relation, about 10% of the esophageal adenocarcinomas occurring in the population may be attributable to intake of LES-relaxing drugs. Cardia adenocarcinoma and esophageal squamous-cell carcinoma were not associated with use of LES-relaxing drugs.

CONCLUSIONS

The widespread use of LES-relaxing drugs may have contributed to the increasing incidence of esophageal adenocarcinoma.

Breast cancer risk and lifetime leisure-time and occupational physical activity (Sweden)

OBJECTIVE

To clarify whether type and timing of physical activity affect postmenopausal breast cancer risk.

METHODS

In a population-based case-control study within the Swedish female population 50-74 years of age, 3347 women with invasive, postmenopausal breast cancer (84% of all eligible) and 3455 controls (82% of all selected) reported on past leisure-time physical activity. Record linkage to decennial census data (1960-1990) provided estimates of their occupational physical activity. Odds ratios with 95% confidence intervals were estimated by multivariate logistic regression.

RESULTS

After adjustment for potential confounders, women in sedentary occupations during their reproductive years (25-44 years of age) had a 50% higher risk for postmenopausal breast cancer, compared to those with the physically most demanding jobs. Only the most recent leisure-time physical activity was associated with a significant risk reduction. Women with the combination of sedentary jobs and lack of leisure-time exercise had a three-fold higher risk of breast cancer, compared to the physically most active both inside and outside the workplace.

CONCLUSION

Effects of occupational and leisure-time physical activity on breast cancer risk appear to have different latency times, and/or to be effect-modified by age or reproductive status. Although chance might explain our findings, it is advisable to consider type and timing of physical activity in future studies.

Viral load of human papilloma virus 16 as a determinant for development of cervical carcinoma in situ: a nested case-control study

BACKGROUND

Infection with certain types of human papillomavirus (HPV), which is common among young women, increases the risk of cervical cancer. However, less than 1% of young women positive for oncogenic types of HPV develop cervical cancer. We investigated whether the amount of HPV DNA is a useful predictor of progression to cervical carcinoma in situ.

METHODS

We estimated the amount of HPV 16 DNA by a PCR that uses the 5'-exonuclease (Taqman) method, in 478 women with cervical carcinoma in situ and 608 individually matched controls. To adjust for differences in the amount of genomic DNA between samples, we estimated the amount of a nuclear gene (beta-actin). We studied multiple smears (total 3835 archived samples) from each woman, taken over periods of up to 26 years, that covered normal cytology to development of cervical cancer.

FINDINGS

The risk of cervical carcinoma in situ increased with the amount of HPV 16 DNA. Analysis of the first smear from each woman, collected a mean of 7.8 years before cancer diagnosis, showed that women with the 20% highest amount of HPV 16 DNA were at a 60-fold higher risk of developing cervical carcinoma in situ than women negative for HPV 16. The first smear samples were classified as normal by squamous-cell cytology.

INTERPRETATION

Analysis of the amount of HPV DNA can predict cancer risk at a stage when current screening methods are uninformative. Testing for the amount of HPV 16 DNA during gynaecological health checks might strikingly improve our ability to distinguish between infections that have a high or low risk of progressing into cervical cancer.

Consistent high viral load of human papillomavirus 16 and risk of cervical carcinoma in situ: a nested case-control study

BACKGROUND

Persistent infection with certain types of human papillomavirus (HPV) is believed to be a prerequisite for the development of cervical neoplasia. Persistence may depend on certain characteristics, such as viral load, which has so far been given little attention. We investigated the association between HPV 16 viral load and cervical carcinoma in situ.

METHODS

We did a nested case-control study of women participating in cytological screening in Sweden. We used a sensitive quantitative PCR assay to estimate HPV 16 load in multiple smears for each woman, taken during a period of up to 26 years before diagnosis. We calculated C, values, which decrease as the number of viral DNA copies increases.

FINDINGS

2081 smears from 478 cases and 1754 smears from 608 controls were tested. Among cases, we found a consistently increased load of HPV 16 already 13 years or more before diagnosis, and when many smears were still cytologically normal. Women with high HPV 16 viral loads were at least 30 times the relative risk of HPV-16-negative women more than a decade before diagnosis. The increase in relative risk was constant over time. About 25% of women (95% CI 0.12-0.32) infected with a high viral load before age 25 years developed cervical carcinoma in situ within 15 years.

INTERPRETATION

Cervical carcinoma in situ associated with HPV 16 occurs mainly in HPV-16-positive women who have consistently high viral loads long term. Women at high risk could be identified by use of a quantitative HPV test in addition to cytological screening.

Lifestyle factors and insulin-like growth factor 1 levels among elderly men

Insulin-like growth factor 1 (IGF-1) is a potentially important determinant of disease; hence epidemiological identification of factors that influence circulating IGF-1 is merited. We therefore analysed data collected in Greece to determine the relationship between anthropometric, lifestyle and dietary variables and serum levels of IGF-1 among elderly men. We identified 51 men with prostate cancer, 50 men with benign prostatic hyperplasia, and 52 apparently healthy elderly men (controls), all matched for age (+/- 1 year). These 153 men provided blood specimens and were interviewed using a validated lifestyle and food frequency questionnaire. We performed multivariate linear regression to identify potential predictors of circulating IGF-1. After controlling for age, body mass index, smoking habits, alcohol drinking and coffee consumption, each 5 cm increase in height predicted a 13.0% increase in IGF-1 (95% CI 0.4-27.2%) among the controls and a 11.3% increase in IGF-1 (95% CI 4.5-18.6%) among the entire study group. None of the investigated dietary factors (total fat, carbohydrate, protein, dairy products, tomatoes, calcium) were strongly related to IGF-1 levels. The positive association between IGF-1 and height integrates the empirical evidence linking IGF-1 and height with prostate cancer risk.