Adjuvant therapy of colon cancer

The status of adjuvant therapy for colon cancer recently was clarified through the use of an innovative statistical evaluation of the existing published data. Even without including the NSABP results, meta-analysis formalized the long-held subjective impression that adjuvant treatment does not worsen patient outcome but, rather, consistently tends to improve it. It is important to recall that even small advantages for therapy of a common disease will have a major public health impact. A review of the results of adjuvant therapy in colon cancer thus far leads to suggestions for future directions, several of which already have been put into practice. Clearly, large-scale cooperative trials are necessary, not only to detect the subtle survival benefits of existing adjuvant therapies, but also to allow for meaningful subgroup analysis. Additional techniques for identifying and quantifying prognostic variables will aid in this latter effort. For example, flow cytometric DNA content analysis is currently in progress on patient specimens from several of the recently completed adjuvant trials, including those conducted by ECOG and NSABP. Not only will such analysis clarify the prognostic relevance of tumor ploidy and proliferative activity but, more importantly, it may identify subsets of patients who derive particular benefit from adjuvant treatment. Lastly, the need for more effective therapies is obvious. The current adjuvant trials employ agents or combinations of agents that hold some promise based on their activity in preliminary trials. However, significant progress will have to await the introduction of new agents with greater activity against colon cancer, and improvement in our understanding and use of specific immunotherapy.