A prospective study of oral contraceptive use and risk of breast cancer (Nurses' Health Study, United States)

Results of previous epidemiologic studies have provided reassurance that there is little, if any, increase in risk of breast cancer with oral contraceptive (OC) use in general. However, in several studies, an increased risk of breast cancer has been observed in two subgroups, young women who used OCs for extended durations and in women who used OCs prior to a first-term pregnancy. We evaluated these relationships using data from the ongoing Nurses' Health Study cohort (United States). We documented 3,383 cases of breast cancer from 1976 to 1992 among 1.6 million person-years of follow-up. We observed no overall relationship between duration of OC use and breast cancer risk, even among women who reported using OCs for 10 or more years (multivariate relative risk [RR]=1.11, 95 percent confidence interval [CI]=0.94-1.32). Among women less than 45 years of age, the multivariate RR for using OCs for 10 or more years was 1.07 (CI=0.70-1.65) compared with never-users. The risk associated with five or more years of OC use prior to a first full-term pregnancy compared with never-use was 0.96 (CI=0.65-1.43). Among women less than 45 years of age, we observed no evidence of an increased risk with OC use before a first full-term pregnancy (use for five or more years: RR=0.57, CI=0.24-1.31). Because of the age distribution of our cohort, we were unable to evaluate these relationships among women less than 40 years of age. Our study provides considerable evidence that long-term past OC use, either overall or prior to a first full-term pregnancy, does not result in any appreciable increase in breast cancer risk in women over 40 years of age.     

Physical activity and the risk of colon cancer among women: a prospective cohort study (United States)

Physical activity has frequently been reported to decrease the risk of colon cancer in men, but data on the relation of physical activity to colon cancer risk in women have generally been less consistent. To further investigate the relationship of physical activity with colon cancer risk in women, we studied a cohort of 31,783 US women participating in the Breast Cancer Detection Demonstration Project Follow-up Study. Information on daily physical activity over the past year was ascertained using a self-administered questionnaire at study baseline. The Cox proportional hazards model was used to estimate relative risks (RRs) relating physical activity to the risk of incident colon cancer. During 270,325 person-years of follow-up, 243 colon cancer cases were identified. No association was observed between physical activity and the subsequent risk of colon cancer. The multivariable RRs of colon cancer across increasing quintiles of total physical activity were 1.0, 1.45, 1.16, 1.27 and 1.15 (95% CI: 0.76, 1.75; p(trend) = 0.77). The multivariable RRs comparing women at the extremes of moderate and vigorous physical activity, respectively, were 1.07 (95% CI: 0.70, 1.62) and 1.10 (95% CI: 0.78, 1.55). The relationship between physical activity and colon cancer risk did not vary by anatomic subsite or across subgroups defined by age, body mass, dietary fiber intake, menopausal status, menopausal hormone use or aspirin use. The results of this large prospective cohort study among women do not support the hypothesis that physical activity is related to a lower incidence of colon cancer.     

Physical activity and risk of ovarian cancer: a prospective cohort study in the United States.

Increased physical activity may lower the risk of ovarian cancer by reducing the frequency of ovulation, decreasing body fat, or diminishing chronic inflammation. Previous epidemiological studies examining the association between physical activity and risk of ovarian cancer have been inconsistent. We investigated the association of physical activity with ovarian cancer in a prospective cohort of 27,365 individuals from the Breast Cancer Detection Demonstration Project. During 227,045 person-years of follow-up, 121 cases of ovarian cancer were ascertained. Usual physical activity during the past year was assessed by a self-administered questionnaire. After adjusting for potential risk factors for ovarian cancer, the relative risks (95% confidence intervals) across increasing quintiles of total physical activity were 1.0, 0.73 (0.43-1.25), 0.84 (0.50-1.40), 0.56 (0.31-1.00), and 0.70 (0.41-1.21), respectively (P for trend = 0.13). In this prospective cohort study among U.S. women, we found no overall significant association between physical activity and risk of ovarian cancer, although the results are suggestive of an inverse association.     

Recent oral contraceptive use and risk of breast cancer (United States)

We examined the association between recent oral contraceptive (OC) use and the risk of breast cancer in data from a large population-based case-control study in the United States. Cases (n=6,751) were women less than 75 years old who had breast cancer identified from statewide tumor registries in Wisconsin, Massachusetts, Maine, and New Hampshire. Controls (n=9,311) were selected randomly from lists of licensed drivers (if aged under 65 years) and from lists of Medicare beneficiaries (if aged 65 through 74 years). Information on OC use, reproductive experiences, and family and medical history was obtained by telephone interview. After adjustment for parity, age at first delivery, and other risk factors, women who had ever used OCs were at similar risk of breast cancer as never-users (relative risk [RR]=1.1, 95 percent confidence interval [CI]=10–1.2). Total duration of usealso was not related to risk. There was a suggestion that more recent use was associated with an increased risk of breast cancer; use less than two years ago was associated with an RR of 1.3 (CI=0.9–1.9). However, only among women aged 35 to 45 years at diagnosis was the increase in risk among recent users statistically significantly elevated (RR=2.0, CI=1.1–3.9). Use prior to the first pregnancy or among nulliparous women was not associated with increased risk. Among recent users of OCs, the risk associated with use was greatest among non-obese women, e.g., among women with body mass index (kg/m²) less than 20.4, RR=1.7, CI=1.1–2.8. While these results suggest that, in general, breast cancer risk is not increased substantially among women who have used OCs, they also are consistent with a slight increased risk among subgroups of recent users.Authors are with the University of Wisconsin Comprehensive Cancer Center, Madison, WI, USA (Dr Newcomb, Ms Trentham Dietz); NIEHS Epidemiology Branch, Research Triangle Park, NC (Dr Longnecker); Fred Hutchinson Cancer Research Center, Seattle, WA (Dr Surer); Department of Obstetrics and Gynecology, Pritzker School of Medicine, The University of Chicago, Chicago, IL (Dr Mittendorf); Department of Community and Family Medicine, Dartmouth Medical School, Hanover, NH (Dr Baron); Boston University, School of Public Health, Boston, MA (Dr Clapp); Department of Epidemiology and Department of Nutrition, Harvard School of Public Health, and Channing Laboratory, Harvard Medical School and Department of Medicine, Brigham and Women's Hospital, Boston, MA (Dr Willett). Address correspondence to: Dr Polly A. Newcomb, University of Wisconsin-Madison Comprehensive Cancer Center, 1300 University Ave., #4780, Madison, WI 53706, USA. Supported by Public Health Service (National Cancer Institute) grants R01 CA 47147 and R01 CA 47305.     

A prospective study of physical activity and the risk of pancreatic cancer among women (United States)

Background  

Several epidemiologic studies have examined the association between physical activity and pancreatic cancer risk; however, the results of these studies are not consistent.     

A prospective study of oral contraceptive use and colorectal adenomas

Purpose

The influence of reproductive factors on colorectal cancer, including oral contraceptive (OC) use, has been examined, but less research is available on OC use and adenomas.

Methods

Participants of the Nurses’ Health Study who had a lower bowel endoscopy between 1986 (when endoscopies were first assessed) and 2008 were included in this study. Multivariable logistic regression models for clustered data were used to estimate odds ratios and 95 % confidence intervals [OR (95 % CIs)].

Results

Among 73,058 participants, 51 % (n = 37,382) reported ever using OCs. Ever OC use was associated with a slight increase in non-advanced adenomas [OR 1.11, 95 % CI (1.02, 1.21)] but not with any other endpoints. Duration of OC use was not associated with adenomas, but longer times since last OC use were associated with increased odds of adenomas [e.g., compared to never use, 15+ years since last use: OR 1.17 (1.07, 1.27)]. Shorter times since last OC use were inversely associated [e.g., ≤4 years since last use: OR 0.74 (0.65, 0.84)].

Conclusions

We observed a modest borderline increase in risk of colorectal adenomas with any prior OC use. Additionally, more recent OC use may decrease risk, while exposure in the distant past may modestly increase risk of adenomas.

     

A prospective study of reproductive factors and exogenous hormone use in relation to ovarian cancer risk among Black women

Purpose

Extensive data in White women have linked oral contraceptive use, tubal ligation, and parity to reduced risk of ovarian cancer; results on postmenopausal female hormone use are mixed. Few studies, all of which are case–control studies, have been undertaken among Black women. The aim of the present study was to prospectively assess associations of reproductive factors and exogenous hormones with ovarian cancer among Black women.

Methods

During follow-up from 1995 to 2013 in the Black Women’s Health Study, a prospective cohort study, 115 incident cases of ovarian cancer were identified. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the relation of the factors of interest to risk of ovarian cancer, with control for covariates.

Result

Oral contraceptive use was inversely associated with ovarian cancer risk: The HR for ≥10 years of use relative to <1 year was 0.50 (95% CI 0.30–0.98). For postmenopausal female hormone use, the HRs for ever use of estrogen with progestin and of estrogen alone were 1.37 (0.73–2.55) and 1.66 (0.90–3.07), respectively. The HRs for parity and tubal ligation were below 1.0, but were not statistically significant.

Conclusion

Overall, the findings indicate that the relation of reproductive factors and exogenous hormone use to risk of ovarian cancer is similar among Black and White women. The results on estrogen-only supplements and estrogen with progestin supplements add to evidence from Whites, indicating that use of hormone supplements may be associated with increased risk of ovarian cancer.

     

Higher incidence of clear cell adenocarcinoma of the cervix and vagina among women born between 1947 and 1971 in the United States

Although the association between in utero exposure to diethylstilbestrol (DES) and clear cell adenocarcinoma of the cervix and vagina (CCA) was first reported among young women, subsequent case reports and cohort studies suggest that an elevated risk for CCA may persist with age. Data from the National Program of Cancer Registries (NPCR) and the Surveillance, Epidemiology and End Results (SEER) Program were used to construct indirect standardized incidence ratios (SIR) comparing CCA risk among women born during the exposure period 1947 through 1971, when DES was prescribed to pregnant women, to the relevant time period for nonexposed women born before or after DES exposure period. CCA incidence among the women born before the DES exposure period (ages 30–54 at diagnosis of CAA) or after the DES exposure period (ages 15–29 at diagnosis) were used to calculate the expected rates for women born during the DES exposure period. Among women aged 15–29 years, CCA risk increased with age and peaked in the 25–29 year age group, but the risk estimates were unstable (SIR = 6.06; 95% CI: 0.97, −251.07, SEER data). Among women aged 40–54 years, CCA risk was greatest in the 40–44 year age group (SIR = 4.55; 95% CI: 1.11, 40.19, SEER data and SIR = 3.94; 95% CI: 1.06, 33.01, NPCR/SEER data) and remained significantly elevated throughout this age group in the combined data set. Risk was not elevated among women aged 30–39 years. The observed risk of CCA, if causally related to DES exposure, reflects a persistent health impact from in utero exposure that is widespread in the general population. When assessing a woman’s cancer risks, whether her mother took DES while pregnant may still be a relevant aspect of the medical history for women born during the period of DES use in pregnancy.     

Early oral contraceptive use and breast cancer among premenopausal women: final report from a study in southern Sweden

In southern Sweden during the 1960s, women began to use oral contraceptives (OCs) extensively at a young age. This case-control study investigates the relationship between the use of OCs and breast cancer development in women in southern Sweden diagnosed in the early 1980s. The risk for breast cancer after OC use among premenopausal women was modeled, after adjustment was made for age, age at menarche, and age at first full-term pregnancy or parity. Both the duration of OC use before 25 years of age and commencement of OC use at a young age were associated with a significant increase in the risk of breast cancer as well as a significant trend. The duration of OC use before the first full-term pregnancy was associated with an increased risk of breast cancer, but it did not show a significant trend. The total duration of OC use was weakly, but not significantly, associated with breast cancer development. The odds ratio for women starting OC use before 20 years of age was 5.8 [95% confidence interval (CI), 2.6-12.8]; for women using OCs for greater than 5 years before age 25, it was 5.3 (95% CI, 2.1-13.2); and for women using OCs for greater than or equal to 8 years before first full-term pregnancy, it was 2.0 (95% CI, 0.8-4.7). In multivariate analyses including the different measurements of OC use, only starting age of OC use was significantly associated with breast cancer. The exposure-response relationship between duration of OC use and risk of breast cancer depended on the age at first use of OCs. Given a fixed duration of OC use, the risk increased with younger starting age of OC use. The findings point to the importance of the early reproductive years as risk determinants for breast cancer after OC use.     

Previous oral contraceptive use and breast cancer risk according to hormone replacement therapy use among postmenopausal women

Objective To assess postmenopausal breast cancer risk in relation to particular patterns of oral contraceptive (OC) use according to hormone replacement therapy (HRT) exposure.Methods Time-dependent Cox regression models were used to analyse information on postmenopausal women from a large-scale French cohort. Among a total of 68,670 women born between 1925 and 1950, 1405 primary invasive postmenopausal breast cancer cases were identified from 1992 to 2000.Results A non-significant decrease in risk of around 10% was associated with ever OC use as compared to never OC use in postmenopausal women. No significant interaction was found between OC and HRT use on postmenopausal breast cancer risk. Breast cancer risk decreased significantly with increasing time since first OC use (test for trend: p=0.01); this was consistent after adjustment for duration of use or for time since last use.Conclusion No increase in breast cancer risk was associated with previous OC exposure among postmenopausal women, probably because the induction window had closed. Some women may develop breast cancer soon after exposure to OCs, leading to a deficit of cases of older women. Further investigation is therefore required to identify young women at high risk.* Address correspondence to: F. Clavel-Chapelon, Equipe E3N-EPIC, INSERM “Nutrition, Hormones, Cancer”, Institut Gustave-Roussy, 94805 – Villejuif, France.     

Malignant melanoma and oral contraceptive use among women in California

Women who had used oral contraceptives, particularly long-term users, were found to have higher rates of malignant melanoma and of a past history of skin cancer than those who had never used oral contraceptives. This excess was confined to lesions of the lower limb. The association between oral contraceptive use and melanoma was noted in 3 separate sets of data, although it was statistically significant only in one. The possibility that this relationship is indirect because, for example, oral contraceptive users are more likely than never-users to be exposed to sunlight and thus to develop malignant melanoma, cannot be excluded.     

Spontaneous abortion and risk of fatal breast cancer in a prospective cohort of United States women

Controversy exists over the possible relationship between induced and spontaneous abortion and risk of breast cancer. Thus, the association of fatal breast cancer and spontaneous abortion was examined in a large prospective study of United States adult women. After seven years of follow-up, 1,247 cases of fatal breast cancer were observed among 579,274 women who were cancer-free at interview in 1982 and who provided complete reproductive histories. Results from Cox proportional hazards models, adjusted for other risk factors, showed no association between a history of spontaneous abortion and risk of fatal breast cancer (rate ratio [RR]=0.89, 95 percent confidence interval [CI]=0.78–1.02). The RR did not increase with increasing numbers of abortions. Parous women who had a spontaneous abortion before their first term birth were not at increased risk compared with parous women with no history of spontaneous abortion (RR=0.76, CI=0.54–1.05). Women whose only pregnancy ended in a spontaneous abortion were not at increased risk compared with women who were never pregnant (RR=0.61, CI=0.27–1.38) or whose only pregnancy ended in a livebirth (RR=0.72, CI=0.32–1.65). These findings do not support an association between spontaneous abortion and fatal breast cancer.     

A prospective study of diet and stomach cancer mortality in United States men and women.

Frequent consumption of fruits, vegetables, and whole grains has been associated with a reduced risk of stomach cancer in the majority of case-control studies of these factors: however, prospective studies have been less consistent. We examined the association between selected major food groups (citrus fruits, vegetables, whole grains, and processed meats) and risk of fatal stomach cancer in the Cancer Prevention Study (CPS) II cohort of 1.2 million United States men and women. During 14 years of follow-up, we documented 439 stomach cancer deaths in women and 910 in men after exclusion of individuals with prevalent cancers, inadequate diet information, and recent weight loss at baseline in 1982. After controlling for other risk factors, none of the food groups examined were associated with risk of stomach cancer except for an unexpected increased risk with vegetable consumption in women [relative risk (RR) = 1.25; 95% confidence interval (CI), 0.99-1.58; highest versus lowest tertile, P = 0.06 for trend]. A high overall plant food intake (a sum of vegetables, citrus fruit, and whole grains) was associated with reduced risk in men (RR = 0.79; 95% CI, 0.67-0.93; highest versus lowest tertile, P = 0.003 for trend), but not in women (RR = 1.18; 95% CI, 0.93-1.50; P = 0.16 for trend). Of individual foods examined, liver consumption greater than twice/week was associated with an increased risk of fatal stomach cancer in women (RR = 1.96; 95% CI, 1.09-3.53) and men (RR = 1.63; 95% CI, 1.02-2.62) compared with nonconsumers. This study supports a modest role for plant foods in reducing the risk of fatal stomach cancer in men, but not in women.     

A case-control study of oral contraceptive use and breast cancer

Among 989 cases of breast cancer and 9,890 controls selected from a cohort of married, female registered nurses aged 30-55 years, the relative risk (RR) of breast cancer for women who had ever used oral contraceptives (OC) compared with those who had never used them was 1.0, with 95% confidence limits 0.9-1.2. Among OC users, there was no consistent pattern of excess risk with increasing duration; in fact, the few women who had used OC longest (greater than 10 yr) had a slightly lower risk than never-users. Moreover, there was no association between OC use and breast cancer among women with a positive history of breast cancer in the mother or sister or with OC use before their first pregnancy. The only subgroup of women among whom any adverse effect was apparent was current OC users aged 50-55 years (two onsets expected vs. seven observed). This finding is consistent with earlier reports of an increased risk of breast cancer among older OC users; however, it is also likely to reflect, at least to some extent, the play of chance, since at ages 45-49 and in each younger age group fewer cases than expected were observed among current OC users.     

Soft tissue sarcoma and tobacco use: data from a prospective cohort study of United States veterans

A report of an increased risk of soft tissue sarcoma (STS) among users of smokeless tobacco led us to evaluate this association and the role of other types of tobacco in a prospective cohort mortality-study of United States veterans. A total of 248,046 veterans provided tobacco-use histories on a mail questionnaire in 1954 or 1957. Data on subsequent tobacco use were not collected. By 1980, 119 deaths from STS had occurred among the cohort members. Veterans who had ever chewed tobacco or used snuff had a nonsignificant 40 percent excess of STS (95 percent confidence interval [CI]=0.8–2.6; 21 deaths) in comparison with veterans who had never used any tobacco products. Risk was limited to former users (relative risk [RR]=1.5) with no excess seen among current users (RR=0.9). Frequent former users had higher risk (RR=1.9) than infrequent users (RR=1.3). Risk was slightly higher in persons who started using smokeless tobacco at younger ages, but did not increase with duration of use or with late age at cessation of use. Most veterans who used chewing tobacco or snuff also used some other form of tobacco. No STS deaths occurred among the 2,308 veterans who used smokeless tobacco only. An unexpected finding of the study was the significant excess of STS deaths among cigarette smokers (RR=1.8, CI=1.1–2.9). Risk was higher among ex-smokers (RR=2.2) than among current smokers (RR=1.5) and was not related to number of cigarettes per day, age started smoking, duration, or pack-years. Pipe and cigar smokers also experienced a nonsignificant excess risk (RR=1.6). The study findings may have been affected by limitations in the histories of tobacco use, the quality of death certificate data on STS, and the small number of STS deaths, particularly among users of smokeless tobacco.Drs Zahm and heineman are with the Occupational Studies Section, Environmental Epidemiology Branch, Epidemiology and Biostatistics Program, National Cancer Institute, Rockville, MD, USA. Dr Vaught is with Westat, Inc., Rockville, MD. USA. Address correspondence to Dr Zahm, Occupational Studies Section, National Cancer Institute, Executive Plaza North, Room 418, Rockville, MD 20892, USA.     

Inverse association of NSAID use and ovarian cancer in relation to oral contraceptive use and parity

We examined the association between non-steroidal anti-inflammatory drug (NSAID) use and ovarian cancer by potential effect modifiers, parity and oral contraceptive use, in a population-based case-control study conducted in Wisconsin and Massachusetts. Women reported prior use of NSAIDs and information on risk factors in a telephone interview. A total of 487 invasive ovarian cancer cases and 2653 control women aged 20-74 years were included in the analysis. After adjustment for age, state of residence and other covariates, ever use of NSAIDs was inversely associated with ovarian cancer in never users of oral contraceptives (odds ratio (OR)=0.58, 95% confidence interval (CI) 0.42-0.80) but not for ever users (OR=0.98, 95% CI 0.71-1.35) (P-interaction=0.03). A reduced risk with NSAID use was also noted in nulliparous women (OR=0.47, 95% CI 0.27-0.82) but not among parous women (OR=0.81, 95% CI 0.64-1.04) (P-interaction=0.05). These results suggest that use of NSAIDs were beneficial to women at greatest risk for ovarian cancer.     

Trends in oral contraceptive and intrauterine device use among reproductive-aged women in the US from 1999 to 2017

Purpose

Since the 1960s, increasing oral contraceptive (OC) use has mirrored decreasing ovarian cancer incidence. The impact of intrauterine devices (IUDs) on cancer risk is less well established. With improved access and increased options, we must consider how changing usage can affect cancer risks.

Methods

Nationally representative data from the National Health and Nutrition Examination Survey (NHANES, 1999–2016) and the National Survey for Family Growth (NSFG, 2006–2017) were used to evaluate contraceptive use over time in premenopausal women (NHANES n?=?13,179; NSFG n?=?26,262). Trends were assessed overall and by race, age, pregnancy history, education, and body mass index.

Results

The average annual absolute increase in self-reported IUD use was 0.81% (NSFG), while OC use decreased 0.49% in NSFG and 0.47% in NHANES. This represents a significant decrease in OC use in NSFG [annual percent change (APC) ? 2.2% (95% CI ? 3.4, ? 1.0%), p?<?0.01]. Trends in OC use varied somewhat by pregnancy history in NHANES (p-interaction?=?0.054). In contrast, IUD use increased 6.2% annually [(1.4, 11.2%), p?=?0.03] and varied significantly by pregnancy history (p-interaction?<?0.01). Nulligravid women increased IUD use 11.0% annually [(2.6, 20.1%), p?=?0.02] compared to women with prior pregnancy at 5.2% [(0.4, 10.2%), p?=?0.04]. In 2015–2017, IUD use was 76.5% hormonal (71.1, 81.8%) and 22.9% copper (17.4, 28.3%) with greater hormonal IUD use in obese women [89.4%, (82.9, 95.9%)].

Conclusion

Increasing IUD use outpaced declining OC use in premenopausal US women. There may be a resulting decreased gynecologic cancer risk as more women gain access to potentially risk-reducing contraceptives.

     

Timing of births and oral contraceptive use influences ovarian cancer risk

Increasing parity and duration of combined oral contraceptive (COC) use provide substantial protection against ovarian carcinoma (cancer). There are limited data on the impact of the age of the births or age of COC use on reducing ovarian cancer risk. Here, we examined the effects of age at first and last births and age at use of COCs using data from studies conducted in Los Angeles County, California, USA (1,632 cases, 2,340 controls). After adjusting for the number of births, every 5 years that a first birth was delayed reduced the risk of ovarian cancer by 13% (95% CI 5–21%; p = 0.003); a first birth after age 35 was associated with a 47% lower risk than a first birth before age 25. COC use before age 35 was associated with greater protection per year of use than COC use at older ages. Considering previously published results as well as the results presented here, increasing parity and a later age at births are both important protective factors against ovarian cancer and the protection extends over 30 or more years from last birth. Current models of the etiology of ovarian cancer do not encompass an effect of late age at births. Our result of an attenuation of the protective effect with COC use after around age 35 needs further investigation as it has not been seen in all studies.     

A prospective cohort study of physical activity and body size in relation to prostate cancer risk (United States)

Objectives: To examine the associations of physical activity and body size with risk of prostate cancer. Methods: At baseline in 1988, 8922 men (mean age 67 years) completed a health questionnaire which included information on physical activity, body weight, and waist girth. In a subgroup (74% of men), physical activity data also had been provided in 1962 or 1966 and again in 1977. Additionally, body weight measured at age 18 was available for 92% of men. During follow-up from 1988 through 1993, 439 men developed prostate cancer. Results: In multivariate analyses that accounted for potential confounders, the RRs (95% CI) for <4200, 4200–8399, 8400–12,599, and 12,600 kJ/week of physical activity at baseline were 1.00 (referent), 1.13 (0.84–1.52), 0.96 (0.68–1.35), and 1.04 (0.79–1.38), respectively. For body mass indexes (BMI) of <22.5, 22.5–24.9, 25.0–27.4, and 27.5 kg/m² at baseline, corresponding results were 1.00 (referent), 1.27 (0.94–1.71), 1.26 (0.92–1.72), and 1.02 (0.68–1.53), respectively. For waist girths of 86.4, 86.5–91.4, 91.5–96.5, and >96.5 cm, they were 1.00 (referent), 1.30 (0.96–1.76), 1.31 (0.96–1.80), and 1.19 (0.85–1.65), respectively. Combining physical activity measures from the past, or examining vigorous activities only, did not yield any significant associations. BMI at age 18 also was not related to risk. Conclusion: These findings do not support a role of physical activity or body weight in prostate cancer etiology.