Abstract:

Objective

To analyze the clinical features of TNM staging of triple negative breast cancer (TNBC)and risk factors affecting its prognosis.

Methods

From January 2005 to June 2007 a total of 429 breast cancer patients confirmed pathologically after operation in our hospital were collected in this study. Among them 98 patients were diagnosed as triple negative breast cancer (TNBC) and the rest 331 as non-triple negative breast cancer (NTNBC). All patients were staged according to the staging system (IUCC/AJCC, the 6th edition) and the two groups of patients were compared and analyzed.Comparison of pathobiological behaviours and TNM stages between the two groups was done using chi-square test or rank sum test. Kaplan-Meier method, drawing survival curve and Log-rank test were used for survival analysis. Cox regression was used for analysis of death risk factors for TNBC patients.

Results

TNBC patients accounted for 22.84% (98/429)and NTNBC for 77.16% (331/429). The comparison between the TNBC group and the NTNBC group showed significantly statistical difference in histology grade (grade Ⅲ,41.84% vs 21.45%), pathobiological types ( invading ductal cancer, 73.47% vs 59.82%), local recurrence after operation (27.55% vs 13.29%), tumor diameter(maximum diameter of primary tumor ＞5 cm,41.84% vs 25.08%),metastasis of lymph nodes (56.12% vs 39.88%)and organ metastasis (25.51% vs 12.69%) (P ＜0.050).The comparison of TNM stage between the TNBC group and the NTNBC group showed no statistical difference in stage I (8.16% vs 16.01%), stage IIa (17.35% vs 26.28%) and stage IIb (17.35% vs 26.89%) (P ＞0.050),but significant difference in stage Ⅲa(24.49% vs 15.71%),stage Ⅲb (12.25% vs 6.04%),stage Ⅲc (9.18% vs 3.93%)and stage Ⅳ(11.22% vs 5.14%)(P＜0.050). The 5-year overall survival and disease free survival in the TNBC group was markedly lower than in the NTNBC group ( 76.53% vs 89.73% and 63.27% vs 74.32% )( P ＜0.050). The median survival time was 54.082 months (95% CI 48.880 ～59.283) in the TNBC group and 59.000 months (95% CI 51.515 ～63.849) in the NTNBC group. TNM stage Ⅲ, Ⅳ(χ² =5.094,P=0.024) and lymph node metastasis(χ² = 4.375,P = 0.036) and organ metastasis (χ² = 6.064,P =0.012) were the risk factors affecting the prognosis of TNBC patients.

Conclusion

The TNM staging system for breast cancer well reflect the clinical features of invasion, recurrence and metastasis of TNBC. TNM stage Ⅲand Ⅳ, lymph node metastasis and organ metastasis are dependent factors affecting the prognosis, and distant metastasis is the most important factor of death for TNBC.

Key words: breast neoplasms, triple negative, TNM stage, prognosis factors