La radioterapia preoperatoria nel cancro del retto: Frazionamento convenzionale

Experiences on preoperative radiation therapy with conventional fractionation for rectal cancer are reviewed. Results in terms of local control, survival and sphincter preservation are focused in resectable disease: the impact on resectability, local control and survival are analysed in unresectable disease. Randomized trials reported in the 80s, demonstrated a significant impact on local control with a pre-op dose of 34.5-40 Gy vs surgery alone. An increased risk of complications was reported because of the suboptimal treatment techniques used. No increase in operative mortality was noted and no impact on survival was reported. Recent non-randomized trials demonstrated more acceptable toxicity with appropriated treatment techniques. Doses of 45-50.4 Gy allowed an high clinical remission rate and downstaging at surgery. A longer interval between radiation therapy and surgery (4-6 weeks) influenced these results and about 75% of patients, who were declared to need an abdominoperineal resection at diagnosis, underwent conservative surgery. Retrospective studies in unresectable disease reported a resectability rate of 39-64% after 45-60Gy of pre-op radiation therapy. Surgical resection demonstrated an impact on survival in most of these patient series. In conclusion, preoperative radiation therapy with conventional fractionation allows downstaging of initial disease with possible impact on local control, sphincter preservation in resectable disease and surgical resection in unresectable disease.