OBJECTIVE: Breast conserving therapy is highly recommended for the surgical management of patients with early-stage of breast cancer. This study aimed to explore the effect of age on developing distant metastasis following breast conserving therapy or modified radical mastectomy.

PATIENTS AND METHODS: To this aim, medical records of 468 women diagnosed with T1-2, N0-1, and M0 primary invasive breast cancer during 2005-2012 were selected. Patients were treated with either breast conserving therapy or modified radical mastectomy with post-surgical radiation. Kaplan-Meier method was used to estimate the breast cancer-free survival and distant metastatic-free survival rates. Distant metastasis and prognostic factors were modeled by Cox proportional hazards. The Bayesian approach was used to determine the potential threshold of patients’ age at operation and the cure probabilities were estimated through two treatment types according to age change-point.

RESULTS: There was no significant difference in Locoregional recurrence between two treatments type (p=0.83), although a significantly greater recurrence of distant metastasis was observed in the breast conserving therapy group (p<0.001). Considering metastatic-free survival, the age of 40 was estimated as the change-point of age at operation leading to a higher noticeable cure rate in the modified radical mastectomy group.

CONCLUSIONS: Older patients with early-stage of breast cancer treated with modified radical mastectomy had a significant decrease of distant metastasis compared with younger patients with a threshold of 40 for age at operation.