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Background: Physical inactivity is a potentially modifi able breast cancer risk factor. Because few data on this rela tionship exist for black women, we examined the relationship between breast cancer risk and lifetime and time- or age- specifi c measures of recreational exercise activity among white women and among black women. Methods: The Women’s Contraceptive and Reproductive Experiences Study was a multicenter populationbased case – control study of black women and white women aged 35 – 64 years with newly diagnosed invasive breast cancer. We collected detailed histories of lifetime recreational exercise activity during in-person interviews with 4538 case patients with breast cancer (1605 black and 2933 white) and 4649 control subjects (1646 black and 3033 white). Control subjects were frequency-matched to case patients on age, race, and study site. We examined associations between exercise activity measures (metabolic equivalents of energy expenditure [MET]-hours per week per year) and breast cancer risk overall and among subgroups defi ned by race, other breast cancer risk factors, and tumor characteristics by use of unconditional logistic regression. All statistical tests were two-sided. Results: Among all women, decreased breast cancer risk was associated with increased levels of lifetime exercise activity (e.g., average MET-hours per week per year, P trend = .002). An average annual lifetime exercise activity that was greater than the median level for active control subjects was associated with an approximately 20% lower risk of breast cancer, compared with that for inactivity (for 6.7 – 15.1 MET-hours/week/year, odds ratio [OR] = 0.82, 95% confi dence interval [CI] = 0.71 to 0.93; for ≥ 15.2 MET-hours/week/year, OR = 0.80, 95% CI = 0.70 to 0.92). The inverse associations did not differ between black and white women (for MET-hours/week/year, P trend = .003 and P trend = .09, respectively; homogeneity of trends P = .16). No modifi cation of risk was observed by disease stage, estrogen receptor status, or any breast cancer risk factor other than fi rst-degree family history of breast cancer. Conclusions: This study supports an inverse association between physical activity and breast cancer among black women and among white women. [J Natl Cancer Inst 2005;97:1671 – 9]

Certain events of reproductive life, especially completed pregnancies, have been found to influence a woman's risk of breast cancer. Prior studies of the relationship between breast cancer and a history of incomplete pregnancies have provided inconsistent results. Most of these studies included women beyond the early part of their reproductive years at the time induced abortion became legal in the United States.We conducted a case-control study of breast cancer in young women born recently enough so that some or most of their reproductive years were after the legalization of induced abortion to determine if certain aspects of a woman's experience with abortion might be associated with risk of breast cancer.Female residents of three counties in western Washington State, who were diagnosed with breast cancer (n = 845) from January 1983 through April 1990, and who were born after 1944, were interviewed in detail about their reproductive histories, including the occurrence of induced abortion. Case patients were obtained through our population-based tumor registry (part of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute). Similar information was obtained from 961 control women identified through random digit dialing within these same counties. Logistic regression analysis was used to estimate odds ratios and confidence intervals (CIs).Among women who had been pregnant at least once, the risk of breast cancer in those who had experienced an induced abortion was 50% higher than among other women (95% CI = 1.2-1.9). While this increased risk did not vary by the number of induced abortions or by the history of a completed pregnancy, it did vary according to the age at which the abortion occurred and the duration of that pregnancy. Highest risks were observed when the abortion was done at ages younger than 18 years--particularly if it took place after 8 weeks' gestation--or at 30 years of age or older. No increased risk of breast cancer was associated with a spontaneous abortion (RR = 0.9; 95% CI = 0.7-1.2).Our data support the hypothesis that an induced abortion can adversely influence a woman's subsequent risk of breast cancer. However, the results across all epidemiologic studies of this premise are inconsistent--both overall and within specific subgroups. The risk of breast cancer should be reexamined in future studies of women who have had legal abortion available to them throughout the majority of their reproductive years, with particular attention to the potential influence of induced abortion early in life.Epidemiologists compared data on 845 white women who were diagnosed with breast cancer between January 1983 and April 1990, were born after 1944, and lived in King, Pierce, or Snohomish counties in Washington State with data on 961 white women with no breast cancer from the same counties. They wanted to determine whether induced abortion increases the risk of breast cancer. Restricting cases to women born after 1944 allowed the researchers to focus only on legal induced abortions. When the researchers limited the analysis only to women who had been pregnant at least once, the risk of developing breast cancer in women who had had at least 1 induced abortion was 50% greater than those who had not had an induced abortion. This risk differed depending on the age at which the women underwent the induced abortion and the duration of that pregnancy. A gestational age (at the time of the first aborted pregnancy) of 9-12 weeks carried the highest risk of breast cancer (RR = 1.9 vs. 1.4 for =or 8 weeks and =or 13 weeks). Further, the breast cancer risk was greatest among women who underwent the induced abortion when they were less than 18 years old (relative risk [RR] = 2.5). It was especially high for women who were less than 18 years old and who had the abortion between 9 and 24 weeks of gestation (RR = 9). It was also high for those who were at least 30 years old at the time of the abortion (RR = 2.1). Spontaneous abortion was not associated with an increased risk (RR = 0.9). Neither the number of induced abortions nor the history of a completed pregnancy were associated with an increased risk of breast cancer. These findings suggest that an induced abortion during the last month of the first trimester increases the risk of breast cancer and that women who were at a very young age at the time of the first induced abortion face an increased risk of breast cancer.

While most studies have found no association between oral contraceptive use and breast cancer, several studies of younger women have reported an association with long-term oral contraceptive use. PURPOSE. We studied the relationship of patterns of oral contraceptive use to breast cancer risk among younger women. These women have had oral contraceptives available their entire reproductive lives and are now entering the breast cancer-prone years.A population-based, case-control study of breast cancer was conducted in three counties in western Washington State among women born in 1945 or later, ages 21-45. Case patients were 747 women with breast cancer diagnosed in 1983-1990 and identified through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry. Control subjects were 961 women identified by random-digit telephone dialing. Subjects were interviewed in person, using pictures of brands of oral contraceptives and calendars of life events as recall aids.There was no increased incidence of breast cancer associated with ever having used oral contraceptives. Because only 8% of this cohort had never used oral contraceptives, short-term users (1 year) were combined with never users as the reference group for further analyses. A small increased risk of breast cancer was associated with long duration of oral contraceptive use (odds ratio foror = 10 years = 1.3; 95% confidence interval [CI] = 0.9-1.9; P for trend = .03), particularly among women aged 35 years or younger (odds ratio foror = 10 years = 1.7; 95% CI = 0.9-3.1). Breast cancer was also modestly related to oral contraceptive use early in reproductive life (odds ratio for use within 5 years of menarche = 1.3; 95% CI = 1.0-1.8; P for trend = .04) and to use of high-progestin-potency oral contraceptives for at least 1 year (odds ratio = 1.5; 95% CI = 1.1-2.1). These associations were adjusted for age, age at menarche, term pregnancy, induced abortion, and family history of breast cancer. The associations were not further confounded by case-control differences in education, religion, breast feeding of offspring, or infertility; in oral contraceptive contraindications, indications, or complications; or in measures of breast cancer detection such as mammography or breast biopsy.Long-term oral contraceptive use among young women or use beginning near menarche may be associated with a small excess breast cancer risk, possibly due to susceptibility to genetic damage in breast epithelial cells at ages of high breast cell proliferative activity.Future studies should investigate whether the patterns of risk we reported are present as this cohort ages.A case control study was conducted in Washington among 21-45 year old white women from King, Pierce, and Snohomish counties (i.e., Seattle metropolitan area) to examine the relationship between oral contraceptive (OC) use and breast cancer. The 747 cases were diagnosed with invasive breast cancer between January 1983 and April 1990. The researchers combined short term OC users with never users since just 8% of all subjects had never used OCs. They controlled for age, age at menarche, term pregnancy, induced abortion, and family history of breast cancer. Longterm use (i.e., =or 10 years) of OCs was associated with a small increased risk of breast cancer (odds ratio [OR] = 1.3; p for trend = 0.03), especially among women not older than 35 years (OR = 1.7). This finding was consistent with results of other studies. OC use early in reproductive life (i.e., within 5 years of menarche) was also associated with a moderate increase in breast cancer (OR = 1.3; p for trend = 0.04). Breast cancer risk was also elevated among women who used high progestin potency OCs (as defined by the Dickey method for classifying OC potency) for at least 1 year (OR = 1.5). Case control differences in education, religion, breast feeding of children, or infertility; in OC contraindications, indications, complications; or in measures of breast cancer detection (e.g., mammography or breast biopsy) did not confound the associations. An association between breast cancer and long term OC use among young women and OC use beginning close to menarche suggest that puberty, a time when breast epithelial cells are undergoing considerable proliferative activity, are susceptible to genetic damage. Further research is needed to determine whether the aforementioned patterns of breast cancer risk continues as the cohort becomes older.

Fifty-seven female residents of King and Pierce Counties (Washington State) with a new diagnosis of in situ or invasive vulvar carcinoma during 1976-79 were interviewed concerning their menstrual, reproductive, and medical histories. A random sample of women residing in the same area was interviewed for comparison. A greater proportion of women with in situ vulvar tumors than control subjects were of low educational level, reported a history of oral contraceptive use, experienced early age at first birth, late age at menopause, and were current or former cigarette smokers. Menstrual and reproductive factors were similar between women with invasive vulvar cancer and controls, but a greater proportion of cases reported a history of diabetes and of cigarette smoking. The factors found in this study to be associated with in situ vulvar carcinoma are similar to those observed among women with cervical cancer. In addition, since the vulva and cervix both are derived from cloacal tissue, and neoplasms of the two sites occur together more often than would be expected by chance, in situ vulvar and cervical tumors may share some common etiologies.

Female resident of King and Pierce Counties (Washington) in whom carcinoma of the colon or rectum was diagnosed during a 15-month period in 1976-77 were interviewed regarding their menstrual and reproductive histories. A random sample of women from the same population was interviewed for comparison. On the average, women with colon cancer had given birth to fewer children than had controls; compared to the incidence of colon cancer in nulliparous women, the incidence in women with 1 or 2 children was reduced by 30%, whereas the incidence in women with 3 or more children was reduced by 50% (P=0.004). No association was present between parity and rectal cancer. Neither contraceptive nor noncontraceptive estrogen use was related to the incidence of colon cancer. Use of oral contraceptives was more common among women with rectal cancer than among controls, but this result could well have arisen by chance (P=0.09). The data were not adequate to determine whether it was the inability to conceive and deliver a child that was related to colon cancer or the failure to undergo the physiologic changes that accompany pregnancy. Nonetheless, the association of low parity with the incidence of colon cancer has now observed several times, in each instance to a moderately strong degree. This observation suggests that events of reproductive life have a bearing on a woman's subsequent risk of developing colon cancer.

The relationship of weight at birth to the occurrence of childhood cancer was studied with emphasis on the influence of age at diagnosis. Birth certificates for 681 children with cancer born in Washington State were linked with cancer registry data. Among children diagnosed with cancer during the first several years of life, there was an increased proportion with a high birth weight (greater than 4,000 g). The relationship was strongest for children under 2 years of age; about twice as many of them had high birth weights. However, the relationship was not present at all in those whose cancer was diagnosed at age 4 or older. This excess risk in young children associated with high birth weight was distributed among several types of cancer, including the two most common ones (leukemia and neuroblastoma).

The prevalence of several known or suspected risk factors for breast cancer is changing among young women. The time trend in incidence of breast cancer among young women in western Washington was analyzed as a possible predictor of trends in future incidence rates. Data were from the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry. For women age 25-44 years (n = 1,869 cases), the incidence of breast cancer increased by 22% (P less than .001) between the time periods 1974-77 and 1982-84. The estimated annual increase was 2.5% (P less than .001). The increase in incidence over time appeared to be greater among those residing in low-income census tracts of urban counties and among black women. Possible relationships between the observed increase in rates and trends of risk factors for breast cancer are discussed.

Data from a case-control study of childhood brain tumors were analyzed to examine the possibility that paternal occupation in the aerospace industry is related to the development of a brain tumor in offspring. Parents of 51 children with brain tumors diagnosed in western Washington State during 1978-81 were interviewed, and their responses were compared to those of parents of 142 children selected at random from this population. Among all children, proportions of case and control fathers who had ever been employed in the aerospace industry were nearly identical [relative risk (RR) = 0.94; 95% confidence interval (CI) = 0.40-2.19]. Employment in the aerospace industry during the period from 1 year prior to birth to the time of diagnosis and any employment in the manufacturing part of the industry were not associated with increased risk. However, stratification by age at diagnosis revealed an increased risk associated with father's ever-employment in the industry (RR = 2.10; 95% CI = 0.79-5.60) for children under 10 years old. A corresponding decreased risk (RR = 0.12; 95% CI = 0.01-1.08) was found for children over 10 years old. Because of the relatively small number of cases with a positive paternal occupational history, interpretations of the difference in the direction of the association according to age at diagnosis must remain tentative ones.

Female residents of 13 counties of Western Washington, in whom papillary, follicular, or mixed papillary-follicular thyroid carcinomas had been diagnosed between 1974 and 1979 were interviewed regarding their medical and reproductive histories and past exposure to radiation treatments. For comparison, a random sample of women from the same population was interviewed. Women who had received radiation treatments to the head or neck prior to 5 years before interview were 16.5 times (95% confidence interval = 8.1-33.5) more likely than unexposed women to develop cancer. The relative risk (RR) was highest for papillary cancer (19.4) but also was elevated substantially for follicular and mixed papillary-follicular tumors. Women first irradiated at age 19 years or younger had a much higher RR than did women irradiated at age 20 or older. Regardless of prior radiation exposure, women who ever had had a goiter were at increased risk of developing thyroid cancer. Women who had ever developed a goiter had 17 times the risk of developing follicular cancer and almost 7 times the risk of developing papillary cancer as compared with women who never had had a goiter. Risk of thyroid cancer was elevated even among women who had had a history of goiter many years prior to diagnosis. A history of thyroid nodules was also a risk factor for papillary and mixed thyroid cancer. Neither a history of hypothyroidism nor hyperthyroidism was found to increase the risk of thyroid cancer.