Clinical trials on adjuvant therapies in cancer: short-term and long-term results

Short-term results of adjuvant treatments of cancer have been reported all over the world with the specific aid of reducing the period required to determine the cure rate of a potentially curative treatment. While this motivation is important, short-term analyses are not totally unbiased and they require careful evaluation. The most peculiar aspect is that short-term results should properly predict long-term results. Therefore, a complete knowledge of the natural history of the disease under evaluation, an adequate number of patients, adequate follow-up of these patients, as well as a proper statistical analysis are essential to derive useful information from intermediate analysis. This paper attempts to point out these aspects and summarizes the experience of the Istituto Nazionale Tumori of Milan in two different adjuvant studies (breast cancer and non-Hodgkin's lymphomas).