Age at first full-term birth and breast cancer risk in BRCA1 and BRCA2 mutation carriers
In the general population, an early age at first full-term birth confers protection against the risk of developing breast cancer. The relationship between age at first birth and breast cancer risk is not clear for women with a mutation in the BRCA1 or BRCA2 gene. Thus, we undertook a case–control study of women with a BRCA1 or BRCA2 mutation to study the effects of age at first full-term birth matched for other reproductive factors.
Information about reproductive factors, including age at first birth as well as medical history, was collected from a routinely administered research questionnaire. There were 2,295 matched pairs of women with a BRCA1 or BRCA2 mutation included in the final analysis.
There was no significant difference in the mean age at first full-term birth among the BRCA1 (24.9 vs. 25.2; P = 0.10) or BRCA2 mutation carriers (26.5 vs. 26.6 years; P = 0.80). Findings were similar in the analysis limited to cases who were diagnosed with breast cancer prior to age 45.
This matched analysis of a large number of BRCA mutation carriers suggests that age at first birth has little influence on BRCA1 or BRCA2 breast cancer risk.
KeywordsBRCA1 BRCA2 Breast cancer Age at first birth
We would like to acknowledge the study staff, students, and volunteers including Shana Kim, Farah Shoukat, Ellen MacDougall, Zoella Pasta, Nida Mian, Jennifer Ng, Sarah Chin, Hamida Begum, Harmeet Chaudhary, Asrafi Azmi, Shahana Nargis, Clotilde Ngwa, Mai Abdelhadi, Saiveena Penikalapati, Laavanya Somasundaram, and Hannah Horvath who helped with the data collection and data entry.
Other members of the Hereditary Breast Cancer Clinical Study Group: Beth Karlan, Barry Rosen, Tomasz Huzarski, Pal Moller, William D. Foulkes, Georgia Wiesner, Louise Bordeleau, Eitan Friedman, Wendy Meschino, Carrie Snyder, Kelly Metcalfe, Aletta Poll, Nicole Gojska, Ellen Warner, Susan Armel, Rochelle Demsky, Karen Panabaker, Melanie Taylor, Fergus Couch, Siranoush Manoukian, Barbara Pasini, Mary B. Daly, Linda Steele, Howard Saal, Taya Fallen, Marie Wood, Wendy McKinnon, Edmond Lemire, Albert E. Chudley, Kim Serfas, Kevin Sweet, Seema Panchal, Christine Elser, Ophira Ginsburg, Stephanie Hurst, Carey A. Cullinane, Robert E. Reilly, Joanne L. Blum, Theodora Ross, Caitlin Mauer, Ava Kwong, Cezary Cybulski, Jeanna McCuaig, Daniel Rayson, and Claudine Isaacs.
Joanne Kotsopoulos is the recipient of a Canada Research Chair (Tier II). Steven A. Narod is the recipient of a Canada Research Chair (Tier I). This study was supported by a Canadian Cancer Society Research Institute grant (703058). This work was supported the Peter Gilgan Tour de Bleu Foundation.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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