R. Sowmya Rao

Risk of breast cancer in women exposed to diethylstilbestrol in utero: preliminary results (United States)

BACKGROUND: A synthetic estrogen, diethylstilbestrol (DES), was widely prescribed to pregnant women during the 1950s and 1960s but was later discovered to be associated with an increased risk of clear-cell carcinoma of the vagina and cervix in female offspring. DES has not been linked to other cancers in female offspring, but studies of other prenatal factors such as twin gestation and pre-eclampsia have indicated that in-utero estrogen levels may influence breast cancer risk. We evaluated the relation of in-utero DES exposure to the risk of adult breast cancer.METHODS: A cohort of 4821 exposed women and 2095 unexposed women, most of whom were first identified in the mid-1970s, were followed by mailed questionnaires for an average of 19 years. Reported cancer outcomes were validated by medical record review. Breast cancer incidence in DES-exposed daughters was compared with cancer incidence in unexposed daughters with use of Poisson regression analysis, adjusting for year of birth, age at menarche, age at first birth, and number of births.FINDINGS: The rate ratio for incidence of invasive breast cancer in exposed versus unexposed women was 1.4 (95% confidence interval (CI) = 0.7–2.6). DES exposure was not associated with an increased risk of breast cancer in women under 40 years, but among women aged 40 and older the rate ratio was 2.5 (95% CI = 1.0–6.3). The rate ratio for the association of DES exposure with estrogen receptor-positive tumors was 1.9 (95% CI = 0.8–4.5).INTERPRETATION: While not statistically significant, the overall 40% excess risk, arising exclusively from the subset of estrogen receptor-positive cases, raises a concern calling for continued investigation.

Risk of melanoma in relation to smoking, alcohol intake, and other factors in a large occupational cohort.

Objective: To investigate whether smoking, alcohol intake, female hormonal or anthropometric factors affect melanoma risk. Methods: Using Cox proportional hazards regression analyses, we analyzed 68,588 white subjects (79% female) from the US Radiologic Technologists (USRT) Study who were cancer-free (other than non-melanoma skin cancer) as of the first of two self-administered questionnaires. Follow-up covered 698,028 person-years, with 207 cases of melanoma. Results: We found that melanoma risk was not associated with height, weight or BMI, nor with age at menarche, menopausal status, use of hormone replacement therapy, parity, age at first birth or oral contraceptive use. Melanoma risk was elevated with increasing alcohol use (RR: 2.1; 95% CI: 0.9–4.8, for >14 drinks/week compared to never drinking; (p(trend) = 0.08)). Smoking for long durations compared to never smoking was inversely related to melanoma risk (RR: 0.6; 0.3–1.3; ≥30 years; p(trend) = 0.03), though risk was not associated with number of packs smoked per day. Conclusions: None of the anthropometric or female reproductive/hormonal factors evaluated were related to melanoma risk. It is unclear whether the positive association with alcohol intake and inverse association with smoking for long duration are causal. The alcohol and smoking findings warrant detailed assessment in studies with substantial statistical power where potential biases can be more fully evaluated.

Breast Cancer Incidence in U.S. Radiologic Technologists

Studies of atomic bomb survivors and medically exposed populations have demonstrated an increased risk of breast cancer associated with acute or protracted, intermediate‐dose or high‐dose, ionizing radiation; however, the risks associated with low‐dose and low‐dose‐rate (protracted) exposures are less certain.

Understanding the factors underlying disparities in cancer screening rates using the Peters-Belson approach: results from the 1998 National Health Interview Survey.

Background:Cancer screening rates vary substantially by race and ethnicity. We applied the Peters-Belson approach, often used in wage discrimination studies, to analyze disparities in cancer screening rates between different groups using the 1998 National Health Interview Survey. Methods:A regression model predicting the probability of getting screened is fit to the majority group and then used to estimate the expected values for minority group members had they been members of the majority group. The average difference between the observed and expected values for a minority group is the part of the disparity that is not explained by the covariates Results:The observed disparities in colorectal cancer screening (5.88%) and digital rectal screening (8.54%) between white and black men were explained fully by the difference in their covariate distributions. Only half of the disparity in the observed screening rates (13.54% for colorectal and 17.47% for digital rectal) between white and Hispanic men was explained by the difference in covariates between the groups. The entire disparity observed in mammography screening rates for black and Hispanic women (2.71% and 6.53%, respectively) compared with white women was explained by the difference in covariate distributions Conclusions:We found that the covariates that explain the disparity in screening rates between the white and the black population do not explain the disparity between the white and the Hispanic population. Knowing how much of a health disparity is explained by measured covariates can be used to develop more effective interventions and policies to eliminate disparity.

Risk of melanoma among radiologic technologists in the United States.

Our study examines the risk of melanoma among medical radiation workers in the U.S. Radiologic Technologists (USRT) study. We evaluated 68,588 white radiologic technologists (78.8% female), certified during 1926–1982, who responded to a baseline questionnaire (1983–1989) and were free of cancer other than nonmelanoma skin at that time. Participants were followed through completion of a second questionnaire (1994–1998). We identified 207 cases, 193 subjects who reported first primary melanoma and 14 decedents with melanoma listed as an underlying or contributory cause of death. We examined risks of occupational radiation exposures using work history information on practices, procedures, and protective measures reported on the baseline questionnaire. Based on Cox proportional hazards regression, melanoma was significantly associated with established risk factors, including constitutional characteristics (skin tone, eye and hair color), personal history of nonmelanoma skin cancer, family history of melanoma and indicators of residential sunlight exposure. Melanoma risk was increased among those who first worked before 1950 (RR = 1.8, 95% CI = 0.6–5.5), particularly among those who worked 5 or more years before 1950 (RR = 2.4; 0.7–8.7; p (trend) for years worked before 1950 = 0.03), when radiation exposures were likely highest. Risk was also modestly elevated among technologists who did not customarily use a lead apron or shield when they first began working (RR = 1.4; 0.8–2.5). Clarifying the possible role of exposure to chronic ionizing radiation in melanoma is likely to require nested case‐control studies within occupational cohorts, such as this one, which will assess individual radiation doses, and detailed information about sun exposure, sunburn history and skin susceptibility characteristics. Published 2002 Wiley‐Liss, Inc.

Correlates of postmenopausal female hormone use among black women in the United States.

Objective To assess correlates of the use of postmenopausal female hormone supplements among black women. Methods We assessed information obtained from 64,564 U.S. black women 21–69 years of age who enrolled in the Black Womens Health Study in 1995 by completing postal questionnaires. Included in the present analyses were 13,352 women 40–69 years of age who had ceased menstruating. Most resided in ten states, with 66% from California, New York, Illinois, Michigan, Georgia, and New Jersey; 41.0% had completed college. Results Among the 13,352 women 40 years of age or older who had ceased menstruating, 49.2% reported ever use of female hormone supplements and 33.3% were using them currently. Unopposed oral estrogens accounted for 63.4% of the medications being used currently. The use of supplements was highest in the western U.S. and lowest in the Northeast. The strongest correlate of use was menopause due to bilateral oophorectomy. Use peaked at 50–54 years of age and then declined, and also was associated positively with lower body mass index, greater years of education, participation in vigorous exercise, and past oral contraceptive use. Use was associated inversely with having a positive history of diabetes, heart attack, or breast cancer. Some of the drug use reported was at variance with suggested guidelines: unopposed estrogen was taken by some women who had a uterus, and estrogen together with a progestin was taken by some women who had had a hysterectomy. Conclusion These data indicate that patterns of use of postmenopausal female hormone supplements among black women who participated in the present study are similar to those documented in white women. Women with risk factors for coronary artery disease were not more likely to use supplements than women at lower risk, a pattern that is not in accordance with suggestions that the greatest benefit of supplements may accrue to high-risk women. Because users differ from nonusers in important characteristics that may affect the incidence of coronary heart disease, breast cancer, and other illnesses, observational studies of the health effects of these medications must control carefully for correlates of use.

Transitional cell cancer of the urinary tract and renal cell cancer in relation to acetaminophen use (United States)

Experimental and epidemiologic evidence have suggested that phenacetin use increases the risk of transitional cell cancers of the urinary tract. The drug is no longer marketed but a commonly used metabolite, acetaminophen, has been linked recently to an increased risk of renal cancer. We assessed the relation of acetaminophen use to the risk of transitional cell cancer of the urinary tract and of renal cell cancer with data from a hospital-based study of cancers and medication use conducted from 1976-96 in the eastern United States. We compared 498 cases of transitional cell cancer and 383 cases of renal cell cancer with 8,149 noncancer controls and 6,499 cancer controls and controlled confounding factors with logistic regression. For transitional cell cancer, the relative risk (RR) estimate for regular acetaminophen use that had begun at least a year before admission was 1.1 (95 percent confidence interval [CI] = 0.6-1.9) based on noncancer controls, and 0.9 (CI = 0.5-1.6) based on cancer controls. RR estimates for use that lasted at least five years, and for nonregular use, were also close to 1.0. For renal cell cancer, the corresponding estimates were again close to 1.0. Our results suggest that acetaminophen, as used in present study population, does not influence the risk of transitional cell cancer of the urinary tract or of renal cell cancer.

Induced and spontaneous abortion in relation to risk of breast cancer (United States)

The relation of induced and spontaneous abortion to the risk of breast cancer is evaluated in a hospital-based case-control interview study conducted in three cities in the United States from 1985 through 1995. Cases were 1,803 women aged 25 to 64 years with newly diagnosed invasive breast cancer; controls were 4,182 women of the same ages admitted for conditions unrelated to reproductive factors. Other breast cancer risk-factors were controlled through multiple logistic regression. The reference for allanalyses was women who had never had an abortion, either induced or spontaneous. Among parous women, the relative risk (RR) estimate was 1.1 (95percent confidence interval [CI] = 0.9-1.5) for induced abortion overall, 1.0(CI = 0.7-1.4) for abortion before the first birth, and 1.3 (CI = 1.0-1.8)for abortion after at least one birth. Among nulliparous women, the relative risk estimate for induced abortion was 1.3 (CI = 0.9-1.9). There was no trend of increased risk with number of abortions, nor was there consistent evidence of an increased risk in any particular subgroup. Spontaneous abortion was not associated with increased risk of breast cancer, either among nulliparous women or among parous women. These findings provide little support for the hypothesis that induced abortion increases breast cancer risk overall or in particular subgroups.

Height and Breast Cancer Risk: Results from the Black Women's Health Study (United States)

Objectives: Numerous studies, but not all, have yielded positive associations between adult height and risk of breast cancer. There are few data on black women. We evaluated adult height in relation to breast cancer in data from the Black Womens Health Study, a prospective cohort study of 64,530 African-American women aged 18–69 years at baseline in 1995. Methods: A total of 910 cases of breast cancer were analyzed: 700 prevalent cases reported at baseline and 210 incident cases that occurred during the first 2 years of follow-up. A comparison group of controls frequency-matched on 5-year category of birth year was chosen from among participants who had not developed breast cancer. Odds ratios (OR) were calculated for various categories of adult height compared to a reference category of height less than or equal to 61 inches (155cm), with control for current age, age at menarche, and years of education. Results: Increased height was associated with an increased risk of breast cancer overall (p trend = 0.001); the OR for the highest category of height, >69 inches (175cm), was 1.6 (95% confidence interval 1.1–2.3). The association was stronger among premenopausal women and women who had less than 16 years of education. Results were similar for prevalent and incident cases. Conclusion: The present findings indicate that height is associated with breast cancer risk in African-American women.

Oral contraceptive use and breast cancer risk among African-American women

Recent epidemiologic studies, most of them in predominantly White populations, have suggested that long duration of oral contraceptive (OC) use may increase the risk of breast cancer at young ages. We assessed the relationship of OC use to the risk of breast cancer in African-American women aged 25 to 59 years, using interview data from a multipurpose hospital-based case-control study. Five hundred and twenty-four cases hospitalized for invasive breast cancer were compared with 1,021 controls with nonmalignant conditions unrelated to OC use. Relative risks (RR) and 95 percent confidence intervals (CI) were estimated relative to a reference category of use for less than 12 months; potential confounders were controlled by multiple logistic regression analysis. Among women under age 45, three or more years of OC use was associated with an increased risk of breast cancer: the RR estimate was 2.8 (CI=1.5–5.0) for three to four years of use, and declined to 1.5 (CI=0.8.3.0) for 10 or more years of use. Recency and timing of use did not explain the observed association. Among women aged 45 to 59, OC use was associated with little or no increase in risk: the RR estimate for three or more years of use was 1.3 (CI=0.7–2.4). The findings add to the evidence from studies of White women and a recent study of Black women which have suggested an increased risk of breast cancer at young ages for moderate or long duration use of OCs.