Abstract: Objective To analyze clinicopathological features and selection of adjunctive treatment by different age in premenopausal breast cancer. Methods The data of clinicopathological feature and adjunctive therapy were collected from 571 premenopausal women with breast cancer between January 2009 and December 2016. The patients were divided into 3 groups: 44 cases in group 1, age ≤35, 86 cases in group 2, age 36-40, and 441 cases in group 3, age >40. Clinicopathological feature and adjunctive therapy were compared for the difference among 3 groups. Results It was shown that there were significant differences in body mass index (BMI) and positive HER2 rate among 3 groups (P<0.05). Less patients in group 1 had BMI >25 compared with the patients in other 2 groups. HER2 positive rate of patients in group 1 was 20.45%, much more than in other 2 groups (12.79% in group 2 and 15.87% in group 3). More patients in group 1 selected breast-conserving surgery (22.73%) and sentinel lymph node biopsy (43.18%). There was no statistical difference in postoperative adjunctive chemotherapy, radiotherapy, endocrine therapy and targeted therapy among 3 groups. Less patients in group 3 received ovarian function suppression compared with the other 2 groups(P<0.001). Conclusions It was indicated in this study that patients ≤35 years old with premenopausal breast cancer had lower BMI and higher HER2 positive rate, and they preferred breast-conserving surgery and sentinel lymph node biopsy.

Key words: Young breast cancer, premenopausal, clinicopathological features, adjunctive therapy