Outcomes of Triple-Negative Breast Cancers (TNBC) Compared with Non-TNBC: Does the Survival Vary for All Stages?

Background: Triple-negative breast cancer (TNBC) is associated with aggressive tumor behavior and worse outcomes. In a study at a tertiary care breast unit in a developing country, clinico-pathological attributes and outcomes of patients with TNBC were compared with (c.w.) ER, PR, and/or HER2 expressing tumors (non-TNBC).

Patients And Methods: Medical records of 1213 consecutive breast cancer patients managed during 2004-2010 were reviewed. An evaluable cohort of 705 patients with complete treatment and follow-up (median 36 months) information was thus identified. Patients were categorized per ER, PR & HER2 status into TNBC, and ER/PR+ and/or HER2+ groups. Clinico-pathological parameters, response to NACT, and OS & DFS were compared between TNBC and non-TNBC groups.

Results: TNBC patients (n = 249) comprised 35.3 % of the study cohort (n = 705), and were significantly younger than non-TNBC patients (mean age 49.1 ± 11.2y c.w. 51.8 ± 11.3, p = 0.02). The TNM stage at presentation was similar in the two groups (Stage I and II-37 % c.w. 44.3 %, Stage III-47.5 % c.w. 39.5 %, Stage IV-15.5 % c.w. 16.2 % in TNBC c.w. Non-TNBC; p = 0.09). Tumor size (5.7 ± 2.9 cm TNBC c.w. 5.4 ± 2.8 cm non-TNBC, p = 0.22) was similar but lymph nodal (cN) metastases were more frequent in TNBC (77.3 % c.w. 69.8 %; p = 0.03). TNBC had higher histologic grade (97.1 % gr II/III in TNBC c.w. 91.2 % non-TNBC, p = 0.01) and higher incidence of LVI (20.4 % in TNBC c.w. 13.5 %, p = 0.03). Patient groups received similar multi-disciplinary surgical, radiation, and systemic treatment. Comparable proportion of patients in 2 groups were treated with NACT (42 % c.w. 38 %), which resulted in pathological complete response (pCR) in 27.5 % TNBC patients c.w. 17.1 % non-TNBC patients (p = 0.04). Both OS (81.8 ± 4.52 c.w. 97.90 ± 3.87 months, p < 0.001) and DFS (89.2 ± 5.1 c.w. 113.8 ± 4.3 months, p < 0.001) were shorter in TNBC than non-TNBC group. On stage-wise comparison, OS differed significantly only in stage III (47.4 ± 5.3 months in TNBC c.w. 74.5 ± 4.4 in non-TNBC; p < 0.001). Univariate and multivariate analyses revealed tumor stage and IHC subtyping into TNBC c.w. non-TNBC as most important factors predictive of survival.

Conclusions: TNBC occurred at younger age and exhibited aggressive pathology as compared to non-TNBC patients. Although patients with TNBC exhibited better chemo-sensitivity, they had worse DFS and OS compared to the non-TNBC patients. The survival of Stage III TNBC patients was significantly worse compared to non-TNBC group; while in stages I, II, and IV, survival were not significantly different.