Amil Shah, MDCM, FACP, FRCPC
Rectal cancer has a dual pattern of recurrence: local recurrence within the pelvis and distant metastases. Strategies to improve outcome must, therefore, address these
two areas. Meticulous surgical techniques and pelvic radiation reduce the rate of local pelvic recurrence, while chemotherapy reduces distant metastases. Early studies
of adjuvant chemotherapy led to the development of the NIH Consensus Statement in 1990, which recommends that patients with Stage II or III rectal cancer receive
post-operative pelvic radiation and 5FU-based chemotherapy.
Over the past decade, there have been three important developments in the chemotherapeutic management of colorectal cancer which are germane to adjuvant rectal cancer
treatment. First, it was demonstrated that the anti-tumor activity of 5FU can be enhanced by folinic acid, and this combination is now in routine use. Second, the use
of continuous infusion of 5FU during pelvic irradiation for Stages II and III rectal cancer improves overall patient survival compared with bolus 5FU during pelvic
irradiation. Third, new drugs with different mechanisms of action to 5FU have been discovered. These include irinotecan or CPT-11 and oxaliplatin. CPT-11 is approved
by the Canadian TPD for use in advanced colorectal cancer. Two Phase 2 randomized clinical trials show that the combination of 5FU with folinic acid and CPT-11
improves tumor response rates and overall survival in patients with advanced colorectal cancer. These observations make the clinical investigation of 5FU-folinic
acid with CPT-11 as adjuvant therapy a high priority in patients with resectable rectal cancer.
There is strong evidence that adjuvant chemotherapy improves outcome when used as a component of a multi-disciplinary approach to the curative treatment of Stages II
and III rectal cancer. At present, rectal cancer patients should receive two cycles of 5FU-folinic acid followed by concomitant pelvic radiation with 5FU infusion
followed by two more cycles of 5FU-folinic acid chemotherapy.
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