Brinton, Louise A2; Cook, Michael B2; McCormack, Valerie2; Johnson, Kenneth C2; Olsson, Håkan2; Casagrande, John T2; Cooke, Rosie2; Falk, Roni T2; Gapstur, Susan M2; Gaudet, Mia M2; Gaziano, J Michael2; Gkiokas, Georgios2; Guénel, Pascal2; Henderson, Brian E2; Hollenbeck, Albert2; Hsing, Ann W2; Kolonel, Laurence N2; Isaacs, Claudine2; Lubin, Jay H2; Michels, Karin B2; Negri, Eva2; Parisi, Dominick2; Petridou, Eleni Th2; Pike, Malcolm C2; Riboli, Elio2; Sesso, Howard D2; Snyder, Kirk2; Swerdlow, Anthony J2; Trichopoulos, Dimitrios2; Ursin, Giske2; van den Brandt, Piet A2; Van Den Eeden, Stephen K2; Weiderpass, Elisabete2; Willett, Walter C2; Ewertz, Marianne3; Thomas, David B2
1 Oncology, Department of Clinical Research, Det Sundhedsvidenskabelige Fakultet, SDU2 unknown3 Oncology, Department of Clinical Research, Det Sundhedsvidenskabelige Fakultet, SDU
male breast cancer pooling project results
BACKGROUND: The etiology of male breast cancer is poorly understood, partly because of its relative rarity. Although genetic factors are involved, less is known regarding the role of anthropometric and hormonally related risk factors. METHODS: In the Male Breast Cancer Pooling Project, a consortium of 11 case-control and 10 cohort investigations involving 2405 case patients (n = 1190 from case-control and n = 1215 from cohort studies) and 52013 control subjects, individual participant data were harmonized and pooled. Unconditional logistic regression generated study design-specific (case-control/cohort) odds ratios (ORs) and 95% confidence intervals (CIs), with exposure estimates combined using fixed effects meta-analysis. All statistical tests were two-sided. RESULTS: Risk was statistically significantly associated with weight (highest/lowest tertile: OR = 1.36; 95% CI = 1.18 to 1.57), height (OR = 1.18; 95% CI = 1.01 to 1.38), and body mass index (BMI; OR = 1.30; 95% CI = 1.12 to 1.51), with evidence that recent rather than distant BMI was the strongest predictor. Klinefelter syndrome (OR = 24.7; 95% CI = 8.94 to 68.4) and gynecomastia (OR = 9.78; 95% CI = 7.52 to 12.7) were also statistically significantly associated with risk, relations that were independent of BMI. Diabetes also emerged as an independent risk factor (OR = 1.19; 95% CI = 1.04 to 1.37). There were also suggestive relations with cryptorchidism (OR = 2.18; 95% CI = 0.96 to 4.94) and orchitis (OR = 1.43; 95% CI = 1.02 to 1.99). Although age at onset of puberty and histories of infertility were unrelated to risk, never having had children was statistically significantly related (OR = 1.29; 95% CI = 1.01 to 1.66). Among individuals diagnosed at older ages, a history of fractures was statistically significantly related (OR = 1.41; 95% CI = 1.07 to 1.86). CONCLUSIONS: Consistent findings across case-control and cohort investigations, complemented by pooled analyses, indicated important roles for anthropometric and hormonal risk factors in the etiology of male breast cancer. Further investigation should focus on potential roles of endogenous hormones.
National Cancer Institute. Journal (print), 2014, Vol 106, Issue 3