Breast cancer in men and young women

Breast cancer is the leading cause of cancer deaths and the most common cancer in women worldwide. Most patients are postmenopausal women. Breast cancer in men and young women is rare, and risk factors and tumour biology in these patients differ from that of postmenopausal women. Breast cancer in young women is known to be more aggressive and survival poorer than in breast cancer patients in general. Of the several genetic risk factors of female breast cancer, mutations in BRCA1, and especially BRCA2, are also known susceptibility genes of male breast cancer. The contributing role of other breast cancer genes to the genetic background of male breast cancer is unclear. The aim of this work was to characterize breast cancer in Finnish men and young women and to report the treatment results at Helsinki University Hospital of men diagnosed 1981–2006, and young women diagnosed 1997–2007. We also screened known genetic risk variants of female breast cancer in Finnish male breast cancer patients to detect possible risk factors of male breast cancer. We used immunohistochemistry techniques to profile further the breast cancer tumours of young women, especially in the triple-negative subgroup, to find possible prognostic biomarkers. We found that imaging studies were seldom used to diagnose breast cancer in male patients. Treatment delay was longer than in breast cancer patients in general, and the tumours were more often locally advanced. The five-year overall survival had improved from the previous report in our institution in 1982 from 44% to 75%. CHEK2 c.1100delC mutation was found in 5.9% of male breast cancer patients, and mutations were significantly more frequent amongst male breast cancer patients compared to population controls. In young women, an excess of adverse prognostic markers was detected. The five-year overall survival of 80% was lower compared with 89% for breast cancer patients in general. Breast cancer recurrences were more common in patients with hormone receptor-positive tumours compared to patients with hormone receptor-negative tumours. A total of 10% of patients with local disease at diagnosis experienced a locoregional recurrence. Of these, 40% of the women had been treated with mastectomy, and only one (13%) had received postmastectomy radiation therapy. Androgen receptor-positive tumours in young female breast cancer patients were associated with a significantly shorter overall and disease-free survival compared to patients with androgen receptor -positive tumours. The subgroup of patients with quadruple-negative (triple-negative and androgen receptor -negative) tumours showed a trend of having the best prognosis. Our results suggest that inclusion of CHEK2 c.1100delC mutation analyses as part of genetic testing of male breast cancer patients should be considered. Awareness of male breast cancer should be raised both amongst the general public and healthcare professionals. Our results provide insight into the prognostic effect of the androgen receptor, specifically in young breast cancer patients with triple-negative tumours. Larger studies with a longer follow-up time on this subject are warranted.