Table 3. Characteristics of male breast cancer as index and second primary cancer.
Uknown category not included in chi‐square tests.
HR positive defined as ER or PR positive. HR negative defined as ER and PR negative. HR unknown if both ER and PR are unknown, or one is unknown and the other is negative.
Abbreviations: BC, male breast cancer; ER, estrogen receptor; HR, hormone receptor; PR, progesterone receptor; SPC, second primary cancer.