DO ACUTE SIDE-EFFECTS DURING RADIOTHERAPY PREDICT TUMOR RESPONSE IN RECTAL-CARCINOMA

Patients given preoperative radiotherapy (31.5 Gy in 18 fractions) in a prospective, randomized trial of presumably operable rectal adenocar cinoma, were examined for a possible relation between bowel toxicity m anifested as diarrhoea, and tumour size in the operative specimen, in addition to recurrence rate. The group requiring drugs for diarrhoea h ad significantly smaller tumours at surgery (2.5 cm versus 3.5 cm, p < 0.05). Patients without significant radiation-induced diarrhoea had al so more recurrences (37.5% against 14.3%, p = 0.01). The disease-speci fic survival rate was also significantly better (p = 0.02) at 1.5 and 10 years in patients with diarrhoea WHO grade 3 and 4; 89.5%, 75.9% an d 65.1% compared to 83.5%, 49.3% and 44.4% in patients with no or mini mal radiation-induced loose bowels. These results indicate that the re action of the normal bowel to radiation may correlate to radiation sen sitivity of tumours derived from the same tissue.