The link between tumor response 8 weeks into the treatment and overall survival in metastatic breast cancer patients treated with first-line chemotherapy

The aim of this article was to determine if the initial shrinking of tumors due to combined chemotherapy is correlated with overall survival (OS) in patients with metastatic breast cancer (MBC – spread to other organs).

OS (survival at the end of the treatment) is the best parameter to evaluate treatment benefits in patients with metastatic cancer.  However, due to several factors, OS is frequently replaced by progression-free survival (PFS – survival without tumor progression) or time to progression (TTP – time until the tumor grows).  Unfortunately, even though chemotherapy is favorable in primary breast cancer, the tumor response is limited in MBC.

In this study, 287 patients were randomly given a combination with either epirubicin (Ellence) and paclitaxel (Taxol) (ET) alone or with capecitabine (Xeloda)(TEX).  Only 233 patients were eligible for response evaluation. The most important evaluation was the one at 8 weeks of treatment.
The results showed that median OS was 28 months. 10% of the patients had a new lesion or a progression after 8 weeks of treatment. Only 1 of the patients with progression at 8 weeks had a survival longer than the median OS. Survival longer than the median OS was seen both in patients who had at least a 30 % decrease of the tumor or who had stationary (almost no change) disease. The patients who did not respond to the treatment had poorer OS in comparison to the ones who responded.
 

In conclusion, this study indicates that MBC patients with signs of progression at 8 weeks after the initiation of first-line combination chemotherapy have considerably shorter OS. Clear signs of progression during chemotherapy for metastatic disease indicate that the current therapy has to be replaced by other treatments.