Clinicopathological features of young patients (<35 years of age) with breast cancer in a Japanese Breast Cancer Society supported study

To clarify the clinicopathological features of breast cancer in young females, surveillance data of the Registration Committee of the Japanese Breast Cancer Society were analyzed. The clinicopathological characteristics were compared between young (< 35) patients and non-young (a parts per thousand yen35) patients among 109,617 records registered between 2004 and 2009. The numbers of young and non-young patients were 2,982 (2.7 %) and 106,295 (97.0 %), respectively. The young patients had more cases of a familial history of breast cancer, more subjective symptoms, fewer bilateral tumors, lower BMIs, larger tumors, more positive lymph nodes, fewer instances of an ER-positive status, more instances of an HER2-positive status, more triple-negative tumors and more advanced TNM stages. The young patients more frequently received neoadjuvant chemotherapy and breast-conserving therapy (BCT) compared with the non-young patients. Eighty percent of all patients received adjuvant therapy. The young patients were more frequently treated with chemotherapy, molecular targeted therapy and radiation therapy than the non-young patients. In this study, young patients with breast cancer were diagnosed at more advanced stages and had more endocrine-unresponsive tumors than non-young patients. Further prognostic analyses should be conducted in this cohort.