[Adjuvant chemotherapy for colorectal cancer in Japan-current state and problem areas]

Chemotherapy that targets metastatic colorectal cancer originally developed in Europe and the US, and was introduced to Japan in April, 2005, where it has since headed toward full scale clinical applications. This event created an opportunity to re-evaluate the role of postoperative adjuvant chemotherapy in Japan. In Europe and the US, adjuvant therapy has centered on the intravenous administration of leucovorin/fluorouracil, while in Japan, it has been long-term continuous administration of oral fluoropyrimidine preparations. Despite this difference in historical background,guidelines created in 2005 recommend both LV/5-FU and LV/UFT regimens and there has been increased application of evidence-based adjuvant chemotherapy. The benefits of postoperative adjuvant chemotherapy in stage II and III (high risk of recurrence) colorectal cancer patients have also come to be recognized. Examination of a new survey of 100 medical specialists on the current state of adjuvant chemotherapy for colorectal cancer in Japanese clinical settings revealed that for stage III patients, there is a tendency to choose treatment based on evidence gathered from both home and abroad. In contrast, a solid majority (60%) of stage II patients are treated exclusively with oral fluoropyrimidine despite a lack of, or limited evidence of efficacy. At the same time, half of the physicians who treated stage II patients with adjuvant chemotherapy initially attempted to identify those with a high risk of cancer recurrence and treat them accordingly; which was a breakthrough in the clinical treatment approach. While ongoing comparative Japanese clinical studies that use adjuvant chemotherapy for the treatment of colorectal cancer were noted, consideration was also given to the desired future direction clinical research should take.