Concomitant radiochemotherapy in rectal cancer: methodology and indications

Concomitant radiochemotherapy (CRC) is based on the administration of chemotherapeutic agents concurrently with radiation therapy. It is aimed at the spatial cooperation of radiotherapy (ERT) and chemotherapy and the enhancement of the local action of radiotherapy. In this study the role of ERT enhancement in the treatment of rectal cancer, is analyzed. 5FU is the commonly used drug. Clinical and experimental evidence indicates radiotherapy to be enhanced when the drug is administered in continuous infusion after radiation and for a suitable dose of 5FU. In these conditions, toxicity is usually mild. In contrast, when the drug is administered as bolus, the experimental evidence seems to indicate only additivity. However the clinical experience has shown an improvement in local control and survival at the expense of a higher toxicity. In patients with resectable lesions at high risk for local recurrence, randomized CRC studies have shown a high rate of local control between 85% and 90%, a 5-year survival between 55% and 60%, significantly better as compared to control arms: exclusive surgery (GITSG7 175), exclusive ERT (NCCTG), bolus CRC (Intergroup). Acute toxicity is mostly hematological and gastrointestinal. In patients with lesions unresectable for cure, CRC allows high surgical radicality (85-90%). Complete pathologic response is 4 to 20%. Local control is high (80-90%) and 3-year survival is 70 to 90%. Grade 3-4 acute gastrointestinal toxicity was shown to be higher in combinations with bolus 5FU. In recurrence CRC has been used for palliation. Control of pain to the pelvis was similar to that achieved with radiotherapy alone. In a single experience was CRC used preoperatively and results seem encouraging.