Objective: Liver cirrhosis is associated with increased levels of estrogens, which may be causally related to breast cancer. Because background estrogen levels are lower in men than in women, an estrogen-mediated link between liver cirrhosis and breast cancer would be easier to detect in men.
Methods: Men hospitalized with liver cirrhosis in Denmark from January 1, 1977, to December 31, 1989, were followed up, through record linkage, until the end of December 1993 for the possible occurrence of breast cancer.
Results: A total of 11,642 men with liver cirrhosis were identified and were followed for a mean period of 4.3 yr, for a total of 49,687 person-years. Three cases of male breast cancer were observed whereas 0.75 was expected, for a standardized incidence ratio of 4.0 (95% confidence interval, 0.8-11.7).
Conclusions: Cirrhosis, possibly via high levels of endogenous estrogens, increases the risk of breast cancer in men.