Albergaria et al. BMC Cancer 2011, 11:299 http://www.biomedcentral.com/1471-2407/11/299 Page 7 of 10 Figure 2 Significance of the NPI components to breast cancer mortality risk and survival in TNBC patients. Kaplan-Meier survival curves for tumour size (A) and for lymph node status (B). Both NPI components are highly statistically relevant to predict long term survival in TNBC patients; (C) Hazard ratio (CI 95%) in the TNBC cohort was calculated for tumour size and lymph node status. Patients with triple-negative tumours larger than 5 cm display a 3.2-fold risk of death by breast cancer; Concerning axillary lymph node status, TNBC patients with lymphatic involvement higher than 3 nodes have a 4.5-fold risk of breast-cancer specific death. related death (HR = 3.20, 95% CI: 1.77 to 5.73), com- pared to breast cancer patients with tumours smaller than 5 cm (Figure 2C). Notably, when risk analysis were applied to lymph node status, we observed that TNBC patients with more extensive lymph node invasion, hold approximately 4.5-fold-increased risk of breast-cancer- related death (HR = 4.50, 95% CI: 2.16 to 9.34), com- pared to patients lacking axillary invasion (Figure 2C). Discussion The prognosis of women with TNBC is significantly poor, compared to women with other subtypes of breast cancer. The underlying difference in recurrence and patient mortality rates may be explained in part by dif- ferent routes of metastatic spread [51]. The current the- ory point out to the suggestion that TNBCs metastasize to axillary nodes and bones less frequently than the non-triple-negative subset of breast tumours, favouring a haematogenous spread [32,42-44]. In terms of survival, it has been described that the survival curve shape for TNBC or BBC differs from that of patients with other types of breast cancer: there is a sharp decrease in survival during the first 3 to 5 years after diagnosis, but distant relapse after this time is much less common [31,40,41,52]. In a study published by Dent and colleagues, the median time to death was 3.5 years for TNBC compared to 5.7 years for patients with other cancers [39]. In fact, as we can infer by the survival functions, TNBC experienced a severe decrease in their outcome before 48 months, a curve shape that overlaps with the one draw by the NPI in those patients. These findings reinforce the reliability of NPI as a tool to be reproducibly used in TNBC tumours. In our cohort of TNBC we have found that tumour size is considerably higher compared with other sub- types of breast cancer. This difference in tumours size was strongly significant in relation to luminal, but not so marked when compared with HER2 tumours. Addi- tionally, we found that, histologically, most TNBCs were high grade tumours. These results concerning tumour size and grade are largely in accordance with previous studies where these prognostic factors were studied within breast cancer subtypes, with special emphasis on TNBC versus non-TNBC patients [40,50,53,54]. One of these studies used a notably large series of TNBC (6.370 patients) and non-TNBC (44.704 patients), and similar