Locoregional recurrence of pT3N0M0 breast cancer after mastectomy is not higher than that of pT1-2N0M0: an analysis for radiotherapy

Prognostic validation and therapeutic decision-making of the AJCC eighth pathological prognostic staging for T3N0 breast cancer after mastectomy

BACKGROUND

T3N0 breast cancer might be a distinct clinical and biological entity, with higher heterogeneity and presenting diverse responses to locoregional and systemic therapy. The aim of the current study was to validate the prognostic effect and assess the treatment decision-making of the American Joint Committee on Cancer (AJCC) eighth pathological prognostic staging in T3N0 breast cancer after mastectomy.

METHODS

We retrospectively included 2465 patients with stage T3N0 breast cancer who had undergone mastectomy between 2010 and 2014 using the data from Surveillance, Epidemiology, and End Results program. The primary endpoint of this study was breast cancer-specific survival (BCSS).

RESULTS

Of the entire cohort, 76.0% of patients in the seventh AJCC staging system were restaged to the eighth AJCC pathological prognostic staging system. A total of 1431 (58.1%) and 1175 (47.7%) of them received chemotherapy and postmastectomy radiotherapy (PMRT), respectively. Pathological staging was an independent prognostic factor for BCSS. Using pathological prognostic stage IA as the reference, BCSS gradually became worse with increased hazard ratios. The 5-years BCSS was 96.9%, 95.5%, 91.1%, 85.6%, and 75.5% in pathological prognostic stage IA, IB, IIA, IIB, and IIIA breast cancers, respectively (P < .001). In pathological prognostic stage IA, IB, and IIA breast cancers, the receipt of PMRT or chemotherapy was not correlated with better BCSS. However, PMRT was correlated with better BCSS in pathological prognostic stage IIB disease (P = .006), but not in pathological prognostic IIIA disease. Moreover, chemotherapy was correlated with better BCSS in pathological prognostic stage IIIA disease (P = .006), but not in pathological prognostic stage IIB disease.

CONCLUSIONS

The eighth AJCC pathological prognostic staging system provides more risk stratification of T3N0 breast cancers after mastectomy and might affect individualized decision-making for chemotherapy and PMRT in this patient subset.

Locoregional recurrence of pT3N0M0 breast cancer after mastectomy is not higher than that of pT1-2N0M0: an analysis for radiotherapy

The purpose of this study was to investigate the value of post-operative radiotherapy in the treatment of pT3N0M0 breast cancer after mastectomy. We analyzed the clinical data of 1390 patients with pT1-3N0M0 breast cancer who were admitted and treated from 1998 to 2007 at the Sun Yat-sen University Cancer Center. All patients underwent mastectomy and did not receive radiotherapy. The locoregional recurrence-free survival, distant metastasis-free survival and overall survival of different T stages of breast cancer were compared. The median follow-up duration was 72 months. The 10-year locoregional recurrence-free survival patients with pT1N0, pT2N0 and pT3N0 breast cancers were 95.3, 91.9 and 93.6%, respectively (χ(2) = 2.550, P = 0.279). The 10-year distant metastasis-free survival rates of patients with pT1N0, pT2N0 and pT3N0 breast cancers were 88.1%, 81.0% and 78.4%, respectively (χ(2) = 8.254, P = 0.016). The 10-year overall survival rates of patients with pT1N0, pT2N0 and pT3N0 breast cancers were 91.9%, 83.5% and 73.0%, respectively (χ(2) = 12.403, P = 0.002). Univariate analyses failed to identify any prognostic factors for locoregional recurrence in pT3N0 patients. Multivariate analysis showed that the T stage had no effect on locoregional recurrence. The locoregional recurrence rate in patients with pT3N0M0 breast cancer who underwent mastectomy and did not receive postoperative radiotherapy was not higher than that in patients with pT1-2N0M0 breast cancer who received the same treatment, suggesting that routine adjuvant post-operative radiotherapy should not be recommended in this patient population.