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Abstract Results from studies evaluating the relationship between cigarette smoking and breast cancer have been inconsistent. Though most studies have found that smoking does not alter risk, others have observed both increased and decreased risks associated with smoking. The reasons for these inconsistencies are unclear, but they may be related to differences in study populations, designs, and exposure definitions. In particular, this relationship may vary by age, and few studies have focused on older women many of whom have smoked for very long durations. We conducted a population-based case–control study (975 cases/1007 controls) of women 65–79 years of age in western Washington State. Women who were current smokers, smoked for ≥40 years, had ≥11 pack-years of lifetime smoking, or started smoking before their first full-term birth each had 30–40% elevated risks of breast cancer (p < 0.05). Recency, length, and intensity of smoking are all associated with modest increased risks of breast cancer. A further understanding of the timing of smoking, and its interaction with other factors, may enhance our knowledge of whether and by what mechanisms smoking alters breast cancer risk. [ABSTRACT FROM AUTHOR]

Summary Although breast cancer familial aggregation has been studied in Caucasians, information for African–Americans is scant. We used family cancer history from the Women’s Contraceptive and Reproductive Experiences study to assess the aggregation of breast and gynecological cancers in African–American and Caucasian families. Information was available on 41,825 first and second-degree relatives of Caucasian and 28,956 relatives of African–American participants. We used a cohort approach in which the relative’s cancer status was the outcome in unconditional logistic regression and adjusted for correlated data using generalized estimating equations. Race-specific models included a family history indicator, the relative’s age, and type. Relative risk (RR) estimates for breast cancer were highest for first-degree relatives, and the overall RR for breast cancer among case relatives was 1.96 (95% CI = 1.68–2.30) for Caucasian and 1.78 (95% CI = 1.41–2.25) for African–Americans. The effect of CARE participants’ reference age on their relatives’ breast cancer risk was greatest among first-degree relatives of African–American patients with RRs (95% CI) for ages <45 and =45 of 2.97 (1.86–4.74) and 1.48 (1.14–1.92), respectively. Among Caucasians, first-degree relatives of case subjects were at greater risk for ovarian cancer, particularly relatives younger than 45 years (RR (95% CI) = 2.06 (1.02–4.12)), whereas African–American first-degree relatives of case subjects were at increased cervical cancer risk (RR (95% CI) = 2.17 (1.22–3.85). In conclusion, these racially distinct aggregation patterns may reflect different modes of inheritance and/or environmental factors that impact cancer risk. [ABSTRACT FROM AUTHOR]

Objective: To investigate the relationship between allergy and risk of breast cancer in women 45 years of age and younger. Methods: Data were analyzed from a population-based case–control study of breast cancer in western Washington. Cases were women born after 1944 who were diagnosed with invasive breast cancer (n = 747) between January 1983 and April 1990. Controls (n = 958) were similarly aged women ascertained through random-digit dialing. Cases and controls were interviewed about their history of doctor diagnosed allergies, including detailed information on the specific types of allergies and the age of onset. Using logistic regression we examined the associations between allergy history and breast cancer. Results: A history of allergies was associated with a reduced risk of breast cancer for women older than 35 (odds ratio (OR) = 0.77; 95% confidence interval (CI) = 0.60–0.99), but not for women 35 years or younger (OR = 1.30; 95% CI = 0.94–1.81). There was little difference in effect when age of first allergy onset was examined. No specific type of allergy was associated with breast cancer risk. Conclusion: Our results provide some evidence that a history of allergy may be associated with a reduced risk of breast cancer for women who develop breast cancer between 35 and 45 years of age. Future studies are needed to verify the relationship between immune responses and breast cancer risk. [ABSTRACT FROM AUTHOR]

The relationship between prior condom use and tubal pregnancy was assessed in a population-based case-control study at Group Health Cooperative of Puget Sound during 1981-86. We indication of infertility and no history of sterilization and 674 similarly defined controls who were matched to the cases on age and county of residence. A history of condom use for more than one year was associated with a decreased risk of subsequent tubal pregnancy (RR = 0.74, 95% CI = 0.44, 1.26) adjusted for the effects of age, current use of contraceptive methods, educational level, and age at first intercourse. The effect was more pronounced when condoms had been used during five-year periods with more than one partner (RR = 0.38, 95% CI = 0.15, 1.0) than during five-year periods with one partner (RR = 0.89, 95% CI = 0.45, 1.76). Condom use for less than one year was unrelated to risk of ectopic pregnancy. Since the use of condoms offers protections against sexually transmitted diseases, one or more of which are likely to be casually related to tubal pregnancy, the observed negative association plausibly represents a protective influence of long-term condom use on the occurrence of tubal pregnancy. [ABSTRACT FROM AUTHOR]

Ages at menarche and first birth are established risk factors for breast cancer. The interval between these ages may also affect risk, since the breast is more susceptible to carcinogenic insults during this period than during the parous period. However, few investigators have studied this relation. Using logistic regression, the authors evaluated associations between the timing of reproductive events and breast cancer risk among 4,013 cases and 4,069 controls enrolled in a multicenter, population-based US case-control study of White and African-American women (1994–1998). For White, parous premenopausal and postmenopausal women, those who had an interval of ≥16 years between the ages of menarche and first birth had 1.5-fold (95% confidence interval (CI): 1.0, 2.2) and 1.4-fold (95% CI: 1.1, 1.8) increased risks of breast cancer, respectively, in comparison with those who had ≤5 years between these ages. Adjusting for age at first birth altered these risk estimates somewhat, to odds ratios of 1.5 (95% CI: 0.8, 2.9) and 1.0 (95% CI: 0.6, 1.5), respectively. These associations were stronger for lobular and hormone-receptor-positive tumors but were absent among premenopausal African-American women. The authors conclude that the interval between age at menarche and age at first birth is associated with the risk of hormonally sensitive types of breast cancer, particularly among White women. [ABSTRACT FROM AUTHOR]