Pre-operative radiotherapy in rectal cancer: Evaluation of irradiation effects on cellular undifferentiation and its influence on prognosis

BACKGROUND/AIMS: In spite of the new technology - stapler, antibiotics, ane sthesia and new surgical and diagnostic procedures - the prognosis on treat ment of cancer of the rectum has not changed in the last 50 years. Survival rates of 50-55% seems immutable in all published series. The main course f or those results is the high incidence of recurrence, either local or wides pread. Local recurrence is directly related to the number of undifferentiat ed cells and to the grade of wall invasion. So any kind of treatment that w ould diminish the number of undifferentiated cells and the size or the tumo r wall penetration certaily would decrease the local recurrence rate, lengt hening the interval free from cancer and, perhaps, modifying the long-term survival rate. Between 1978-1996, a total of 287 patients with rectal adeno carcinoma were treated by pre-operative RTD. METHODOLOGY: The same RDT protocol was used in all the patients: 400 cGy, 2 00 cGy/day, during 4 consecutive weeks (anterior and posterior pelvic field s). Surgery was performed 7-10 days after completion of RDT. RESULTS: Statistical analysis of the whole group showed that pre-operative RDT does decrease frequency of undifferentiated cells. Moreover, the incide nce of local recurrence diminished after irradation by 3.48%. Pre-operative RDT reduces tumor volume and wall invasion, as well as the mortality rate due to local recurrence (2.43%) and alters long-term survival rate (80.17%) . CONCLUSIONS: Pre-operative radiotherapy is really effective in reducing the number of undifferentiated cells and in diminishing the carcinomatous infi ltration of the rectal wall.