Do we need adjuvant treatment for rectal cancer?

Abstract

Recent studies have shown improved local control of rectal cancer in patients receiving preoperative radiotherapy. The reduction of local recurrence is about 50% both after 25 Gy in 5 days and 40 Gy over 4 weeks. Furthermore an improvement in survival of about 20% has been found. The long-term side-effects are still not fully evaluated. Adjuvant chemotherapy studies in Dukes' C patients have shown a significant increase in survival of between 22 and 39%. An initial study using 17-1A antibodies also in Dukes' C patients has shown a 30% increase in survival rate. However, a drawback of the trials that tested adjuvant treatment 5 to 10 years ago is that they do not reflect the modern surgical technique using perimesorectal clearance and total mesorectal excision. Centres not using adjuvant therapy are now reporting local recurrence rates of 5-10%, which is superior to surgery plus adjuvant therapy in all previously published trials. It is therefore urgent to study the effects of preoperative irradiation in patients operated on with the current surgical technique and carefully balance the side-effects against the benefits. The aim must be to obtain knowledge of how to select a subgroup of patients who definitely needs preoperative radiotherapy, e.g. those undergoing an abdominoperineal excision. Systemic adjuvant therapy is probably increasing survival rate in Dukes' C patients but more studies are necessary, particularly with the 17-1A antibody.