Abstract
Postmastectomy radiotherapy (PMRT) has become a standard adjuvant postoperative therapy for breast cancer patients with four or more positive lymph nodes. However, some studies have demonstrated that some subgroups of the breast cancer patients with four or more positive lymph nodes did not benefit substantially from PMRT. Therefore, it is of great necessity to identify whether all breast cancer patients with four or more positive lymph nodes who underwent modified radical mastectomy be treated with PMRT. In our study, we first established a prognostic model using the Surveillance Epidemiology and End Results (SEER) database between 1998 and 2001. Univariate and multivariate Cox models were used to assess the prognostic factors, and five risk factors individually associated with prognosis including AJCC stage, AJCC T, Grade, ER status, PR status. Prognostic index of PMRT were defined as the number of risk factor (NRF). The NRF scores correlated well with overall survival of PMRT even if the patients were in the sub-poor prognosis group. Then the prognostic model was validated using the SEER database between 2006 and 2009, and the same results were obtained. In conclusion, different from others studies, our study demonstrated that all patients with four or more positive lymph nodes after modified radical mastectomy need to be treated with PMRT ever if the patients belonged to AJCC T4 in a poor prognosis group.
Highlights
Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death among females worldwide, with an estimated 1.7 million incidence and 521,900 mortalities in 2012 [1]
Different from others studies, our study demonstrated that all patients with four or more positive lymph nodes after modified radical mastectomy need to be treated with Postmastectomy radiotherapy (PMRT) ever if the patients belonged to AJCC T4 in a poor prognosis group
Most of the patients were diagnosed at the age of more than 40-yearold (87.9%). 51.9% of the patients were in stage IIIA according to AJCC stage, and 44.6% of the patients were in AJCC T2 stage and 60.6% of the patients were in N2
Summary
Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death among females worldwide, with an estimated 1.7 million incidence and 521,900 mortalities in 2012 [1]. Postmastectomy radiation therapy (PMRT), a commonly used practice, can prevent locoregional recurrence and increase survival in breast cancer patients after definite surgery [2,3,4]. National Comprehensive Cancer Network (NCCN) guidelines have intended to list PMRT as a recommended therapy for breast cancer patients with four or more positive lymph nodes. Personalized therapy has been favored by oncologists to treat different breast cancer patients. A recent research have shown that PMRT did www.impactjournals.com/oncotarget not have any effect on survival of these patients with four or more positive lymph nodes in a defined subgroup [6]. Whether all breast cancer patients with four or more positive lymph nodes who underwent modified radical mastectomy should be treated with PMRT needs to be tested and validated
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