Dent R et al. (2007) Triple-negative breast cancer: clinical features and patterns of recurrence. Clin Cancer Res 13: 4429–4434

The basal-like subtype of breast cancer, which consists mainly of 'triple-negative' breast cancers (i.e. tumors negative for the estrogen receptor [ER], progesterone receptor [PR] and HER2), is associated with worse survival than other subtypes. A long-term follow-up study compared outcomes of women with triple-negative breast cancer with those of women with other types of breast cancer.

In this single-institution study, 1,601 patients diagnosed with invasive breast cancer during a 10-year period were stratified according to breast cancer subtype. Those with the triple-negative form (11.2% of the cohort) had much greater risks of distant recurrence (hazard ratio 2.6, 95% CI 2.0–3.5; P <0.0001) or death (hazard ratio 3.2, 95% CI 2.3–4.5; P <0.001) within 5 years of diagnosis. Moreover, triple-negative tumors were more likely to be grade III and were of a larger size (3.0 vs 2.1 cm) than were other subtypes. Patterns of distant recurrence were distinct. In women with triple-negative breast cancer the recurrence rate rose rapidly within the first 2 years after diagnosis, with a rapid decrease over the subsequent 5 years. Those with no evidence of progression after 8 years were unlikely to experience disease recurrence. By contrast, in women with other cancer subtypes the risk of recurrence was constant for the 17 years after diagnosis. Following distant recurrence, women with triple-negative tumors had a significantly shorter median survival interval than did those with other tumor types (9 vs 20 months).

The authors believe that staining for ER, PR and HER2 would enable the majority of basal-like tumors to be classified, permitting novel treatments to be directed at this aggressive cancer type.