A recent sub-group analysis of patients in NSABP (the American: National Surgical Adjuvant Breast Project) trials, and all with primary breast cancers smaller than 1 cm in diameter, has recently been reported.
There were 1260 patients with such small tumours in five trials investigating the benefits of chemotherapy or tamoxifen; (236 with ER negative and 1024 with ER positive tumours). Although there was a reduction in the relapse rates, even in these small and generally good prognosis tumours, nevertheless, there was no overall survival advantage detectable after eight years of follow-up.
In the ER negative patients, surgery alone was attended by an 8 year relapse free survival of 79%, which was improved to 94% with the addition of chemotherapy; (this correlated with a relative risk reduction of relapsing of approximately 40%). However, the overall survival, which was slightly greater than 90% did not differ between the two groups (presumably because the relapsing patients had been successfully been put back into remission)– clearly, further follow up beyond 8 years is required.
In the ER positive patients, relapse free survival at 8 years was 86% in the surgery alone group, 92% in the group who had received adjuvant tamoxifen and 94% in the group who had received chemotherapy.
The subject of routine administration of adjuvant chemotherapy to patients with small (less than 1 cm diameter) breast cancers will continue to be debated – and the inclusion of HER-2 status will have to be in future analyses.