The Optimal Duration of Adjuvant Therapy for Stage III Colon Cancer: the European Perspective

The International Duration Evaluation of Adjuvant Therapy (IDEA) collaboration was created to pool data from different studies worldwide in order to assess whether a shorter duration of adjuvant treatment in colon cancer could maintain the expected benefit while reducing toxicity. The results of the IDEA trials were clinically relevant. They confirmed a two- to sixfold reduction in neurotoxicity for the shorter duration across trials. Overall, the 3-year disease-free survival was very similar: only 0.9% lower for the 3 months group. However, the results were partially unexpected, because they revealed a difference among chemotherapy regimens (CAPOX better than FOLFOX) and risk groups within stage III. The similar outcome between 3 and 6 months of CAPOX coupled with the substantial reduction in toxicity makes us use the CAPOX regimen for 3 months for most stage III patients. An exception to this general rule is the patient with very high risk, i.e., either T4N1b-T4anyN2 or anyTN2b where we use 6 months of CAPOX. Our take from the trial results is also that FOLFOX should never be given for 3 months and preferably not used at all in the adjuvant setting. The conduction of the IDEA enterprise was truly global. The European contribution was major with three fourths of patients enrolled in the four European trials. Herein, we review the results of the “3 versus 6” trials and the literature regarding the interpretation of the collected data in Europe and in the rest of the world.