Abstract
PurposeTo validate the 8th edition of the American Joint Committee on Cancer (AJCC) pathological prognostic staging system for breast cancer patients with internal mammary lymph nodes (IMN) metastasis (N3b disease, stage IIIC in 7th AJCC anatomical staging).MethodsBreast cancer patients with IMN metastasis diagnosed between 2010 and 2014 were retrieved from the Surveillance, Epidemiology, and End Results program. Chi-squared test, Log-rank test, Kaplan-Meier method, and Cox proportional hazard analysis were applied to statistical analysis.ResultsWe included 678 patients with N3b disease in this study. Overall, 68.4% of patients were downstaged to IIIA and IIIB diseases from the 7th anatomical staging to 8th pathological prognostic staging. The new pathological prognostic staging system had better discriminatory value on prognosis prediction among IMN-metastasized breast cancer patients, with a 5-year breast cancer-specific survival (BCSS) of 92.7, 77.4, and 66.0% in stage IIIA, IIIB, and IIIC diseases, respectively (P<0.0001), and the 5-year overall survival (OS) rates was 85.9, 72.1, and 58.7%, respectively (P<0.0001). The results of the multivariate prognostic analysis showed that the new pathological prognostic staging was the independent prognosis related to BCSS and OS, the 8th AJCC pathological prognostic stages showed worse BCSS and OS with gradually increased hazard ratios.ConclusionThe 8th AJCC pathological prognostic staging system offers more refined prognostic stratification to IMN-metastasized breast cancer patients and endorses its use in routine clinical practice for this specific subgroup of breast cancer.
Highlights
Breast cancer (BC) is most frequently diagnosed in females and the leading cause of female cancer death in the majority of countries around the world [1]
In the first model, including the biologic factors in the multivariate prognostic analysis, the results showed that infiltrating lobular carcinoma subtype, higher tumor grade (G3), human epidermal growth factor receptor 2 (HER2)-negative, and estrogen receptor (ER)-negative were the independent adverse prognostic factors related to inferior breast cancerspecific survival (BCSS) (Table 3)
The 8th American Joint Committee on Cancer (AJCC) pathological prognostic staging was included in the multivariate prognostic analysis, and the results indicated that the pathological prognostic staging was the independent prognostic factors related to BCSS and overall survival (OS), the 8th AJCC pathological prognostic stages showed worse BCSS and OS with gradually increased hazard ratios (Table 4)
Summary
Breast cancer (BC) is most frequently diagnosed in females and the leading cause of female cancer death in the majority of countries around the world [1]. BC is prone to have lymphatic metastasis at early stages due to its abundant lymphatic drainage, which mainly includes the axillary lymph node (ALN) area and internal mammary lymph node (IMN) area. The majority of breast lymph drainage runs into the ALN chain, of which 9–45% flows into the IMN chain [2]. A literature review, including 9,817 BC patients, showed that 2.9–32.7% of patients presented IMN metastasis [3]. IMN metastasis was more likely to occur in BC patients with advanced disease, medially located tumors, and ALN metastasis [6, 7]. Biological heterogeneity may be presented for this population, and the traditional primary tumor (T)-regional lymph nodes (N)-distant metastasis (M) staging system could no longer accurately predict the survival outcomes of IMN-metastasized BC patients in the era of biomarkers
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