Adjuvant chemotherapy for breast cancer. A pooled estimate based on published randomized control trials.

The use of adjuvant chemotherapy for treating patients with operable breast cancer remains a worldwide controversy. Using the data from published randomized control trials with a minimum two-year follow-up, pooled estimates of relapse-free survival rates and overall survival rates were calculated. Relapse-free survival rates were improved by 12.5% (95% confidence interval [CI] +/- 4.5%) at three years and by 8% (CI +/- 6%) at five years, with studies using multiple agents showing a greater effect. A significant advantage was also present in overall survival rates at three years, but only for studies involving multiple agents (4% +/- 3.5%). Results from combining data for other types of trials were inconclusive. The use of this method is presented to illustrate its value as an explicit and systematic one for combining data from several randomized control trials in assessing a therapeutic controversy.