Radiation therapy, used in combination with adjuvant chemotherapy, has been shown to improve local control and survival of patients with Stage II or III (T3 or any N positive) rectal malignancy. (GIFUR2, GIRLAIFF, GIRFF protocols).

Adjuvant treatment following curative resection is recommended for patients with Stage II or III cancers. The surgeon should indicate in the operative report whether the cancer is above, at, or below the peritoneal reflection. (Cancers at or below the peritoneal reflection are treated as rectal cancers; cancers completely above the reflection are managed as colon cancers.) Adjuvant chemotherapy for rectal cancers requires early referral because treatment should be started within 4 to 8 weeks after operation (maximum 10 weeks). The current recommendation is for six months of outpatient therapy with intravenous 5-Flourouracil and Folinic acid. Studies have shown an approximately 15% absolute improvement in cure (5 year relapse-free survival) in this setting.

For those patients who presented with fixed or high risk cancers requiring radical preoperative radiotherapy, adjuvant chemotherapy is given post-operatively, regardless of the final pathology report, as significant downstaging may have occurred with the radiotherapy (GIRFF). In those patients receiving preoperative short-course radiotherapy, adjuvant chemotherapy is recommended for Stage II or III cancers (GIRFF).

For those patients who underwent resection without preoperative radiotherapy, adjuvant chemotherapy AND radiation are given to those with Stage II or III cancers. The chemotherapy consists of two cycles of bolus 5FU and folinic acid, followed by a 4-6 week course of pelvic radiotherapy given concomitant with continuous infusional 5FU chemotherapy followed by two final cycles of bolus 5FU and folinic acid. (GIFUR2 protocol)

Given the expanding chemotherapeutic options for the management of metastatic colorectal cancer, it is anticipated that adjuvant therapy may be changing significantly over the next decade. An increasing number of clinical trials are ongoing and in development to determine the role of newer agents in the adjuvant setting. Eligible patients should be encouraged to participate in available trials.