Kinlen LJ, Gilham C, Ray R, et al. - Researchers calculated the independent effects of age at first marriage, age at first birth, and the number of sexual partners on breast cancer risk adjusted for parity and other risk factors in the reanalysis of a large international case‐control study performed in 1979‐1982 (2,274 breast cancers, 18,209 controls) via unconditional logistic regression. Age at first marriage, a surrogate for age at starting prolonged cohabitation, is strongly linked with breast cancer risk. This study's findings demonstrate the impact of close contact. Distinguishing the (probably infective) mechanism might lead to effective prevention of breast cancer. It was reported that independent impact of age at first birth is smaller and could be due to residual confounding.