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- Cullinane, CA, et al.
(författare)
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Effect of pregnancy as a risk factor for breast cancer in BRCA1/BRCA2 mutation carriers
- 2005
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 117:6, s. 988-991
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Tidskriftsartikel (refereegranskat)abstract
- Early age at first birth and multiparity have been associated with a decrease in the risk of breast cancer in women in the general population. We examined whether this relationship is also present in women at high risk of breast cancer due to the presence of a mutation in either of the 2 breast cancer susceptibility genes, BRCA1 or BRCA2. We performed a matched case-control study of 1,260 pairs of women with known BRCA1 or BRCA2 mutations, recruited from North America, Europe and Israel. Women who had been diagnosed with breast cancer were matched with unaffected control subjects for year of birth, country of residence, and mutation (BRCA1 or BRCA2). Study subjects completed a questionnaire detailing their reproductive histories. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived by conditional logistic regression. Among BRCA1 carriers, parity per se was not associated with the risk of breast cancer (OR for parous vs. nulliparous = 0.94; 95% CI = 0.75-1.19; p = 0.62). However, women with a BRCA1 mutation and 4 or more children had a 38% decrease in breast cancer risk compared to nulliparous women (OR = 0.62; 95% CI = 0.41-0.94). In contrast, among BRCA2 carriers, increasing parity was associated with an increased risk of breast cancer; women with 2 or more children were at approximately 1.5 times the risk of breast cancer as nulliparous women (OR = 1.53; 95% CI = 1.01-2.32; p = 0.05). Among women with BRCA2 mutations and who were younger than age 50, the (adjusted) risk of breast cancer increased by 17% with each additional birth (OR = 1.17; 95% CI = 1.01-1.36; p = 0.03). There was no significant increase in the risk of breast cancer among BRCA2 carriers older than 50 (OR for each additional birth 0.97; 95% CI = 0.58-1.53; p = 0.92). In the 2-year period following a birth, the risk of breast cancer in a BRCA2 carrier was increased by 70% compared to nulliparous controls (OR = 1.70; 95% CI = 0.97-3.0). There was a much smaller increase in breast cancer risk among BRCA2 carriers whose last birth was 5 or more years in the past (OR = 1.24; 95% CI = 0.79-1.95). A modest reduction in risk of breast cancer was observed among BRCA1 carriers with 4 or more births. Among BRCA2 carriers, increasing parity was associated with a significant increase in the risk of breast cancer before age 50 and this increase was greatest in the 2-year period following a pregnancy.
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- Kotsopoulos, J, et al.
(författare)
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Age at first birth and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers.
- 2007
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Ingår i: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 1573-7217 .- 0167-6806. ; 105:2, s. 221-228
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Tidskriftsartikel (refereegranskat)abstract
- An early age at first full-term birth is associated with a reduction in the subsequent development of breast cancer among women in the general population. A similar effect has not yet been reported among women who carry an inherited BRCA1 or BRCA2 mutation. We conducted a matched case–control study on 1816 pairs of women with a BRCA1 (n = 1405) or BRCA2 (n = 411) mutation in an attempt to elucidate the relationship between age at first full-term pregnancy and the risk of developing breast cancer. Information about the age at first childbirth and other pregnancy-related variables was derived from a questionnaire administered to women during the course of genetic counselling. There was no difference in the mean age at first full-term birth in the cases and controls (24.9 years vs. 24.8 years; P = 0.81, respectively). Compared to women whose first child was born at or before 18 years of age, a later age at first full-term birth did not influence the risk of developing breast cancer (OR = 1.00 per year; 95% CI 0.98–1.03; P-trend = 0.67). Stratification by mutation status did not affect the results. These findings suggest that an early first full-term birth does not confer protection against breast cancer in BRCA mutation carriers. Nonetheless, BRCA mutation carriers opting for a prophylactic oophorectomy as a breast and/or ovarian cancer risk-reducing strategy should complete childbearing prior to age 40 when this prevention modality is most effective.
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- Narod, SA, et al.
(författare)
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Oral contraceptives and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers
- 2002
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Ingår i: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 1460-2105. ; 94:23, s. 1773-1779
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Tidskriftsartikel (refereegranskat)abstract
- Background: Oral contraceptive use has been associated with an increase in the risk of breast cancer in young women. We examined whether this association is seen in women at high risk of breast cancer because they carry a mutation in one of two breast cancer susceptibility genes, BRCA1 and BRCA2. Methods: We performed a matched case-control study on 1311 pairs of women with known deleterious BRCA1 and/or BRCA2 mutations recruited from 52 centers in 11 countries. Women who had been diagnosed with breast cancer were matched to control subjects by year of birth, country of residence, mutation (BRCA1 or BRCA2), and history of ovarian cancer. All study subjects completed a questionnaire about oral contraceptive use. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived by conditional logistic regression. All statistical tests were two-sided. Results: Among BRCA2 mutation carriers, ever use of oral contraceptives was not associated with an increased risk of breast cancer (OR = 0.94, 95% CI = 0.72 to 1.24). For BRCAI mutation carriers, ever use of oral contraceptives was associated With a modestly increased risk of breast cancer (OR = 1.20, 95 % CI = 1.02 to 1.40). However, compared with BRCA1 mutation carriers who never used oral contraceptives, those who used oral contraceptives for at least 5 years had an increased risk of breast cancer (OR = 1.33, 95% CI = 1.11 to 1.60), as did those who used oral contraceptives before age 30 (OR = 1.29, 95% CI = 1.09 to 1.52), those who were diagnosed with breast cancer before age 40 (OR = 1.38, 95% CI = 1.11 to 1.72), and those who first used oral contraceptives before 1975 (OR = 1.42, 95 % CI = 1.17 to 1.75). Conclusions: Among BRCA1 mutation carriers, women who first used oral contraceptives before 1975, who used them before age 30, or who used them for 5 or more years may have an increased risk of early-onset breast cancer. Oral contraceptives do not appear to be associated with risk of breast cancer in BRCA2 carriers, but data for BRCA2 carriers are limited.
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