Background: It has been reported that triple negative phenotype is characterized by aggressive clinical history in Western breast cancer patients, however its pattern of metastatic spread had never been reported in the Chinese population. Considering racial disparities, we sought to analyze the spread pattern for different sites of first recurrence in Chinese triple negative breast cancers.
Methods: A retrospective study of 1662 patients was carried out from a large database of breast cancer patients undergoing surgery between January 1, 2000 and March 31, 2004 at the Cancer Hospital, Fudan University, Shanghai, China. Survival curves were generated using the Kaplan-Meier method and annual relapse hazards were estimated by the hazard function.
Results: We found a statistically significant difference in relapse-free survival (RFS) for locoregional and visceral recurrence (P = 0.007 and P = 0.025, respectively) among the triple negative, ERBB2+ and HR+/ERBB2- subgroups in univariate analysis. In the multivariate Cox proportional hazards regression analysis, RFS for either locoregional or visceral relapse in the triple negative category was inferior to that in HR+/ERBB2- patients (P = 0.027 and P = 0.005, respectively), but comparable to that in ERBB2+ women (both P >0.05). Furthermore, the early relapse peak appeared later in the triple negative group than that in the ERBB2+ counterpart for both locoregional and visceral relapse. On the other hand, when compared with triple negative breast cancers, a significantly lower risk of developing bone relapse was discerned for ERBB2+ women (P = 0.048; HR = 0.384, 95% CI 0.148-0.991), with the borderline significance for HR+/ERBB2- breast cancers (P = 0.058; HR = 0.479, 95% CI 0.224-1.025). In terms of bone metastasis, the hazard rate remained higher for the triple negative category than that for the ERBB2+ subtype.
Conclusion: Based on the site-specific spread pattern in different subgroups, the triple negative category of breast cancers in the Chinese population exhibits a different pattern of relapse, which indicates that different organotropism may be due to the different intrinsic subtypes. A better knowledge of the triple negative category is warranted for efficacious systemic regimens to decrease and/or delay the relapse hazard.