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, anesthesia and new surgical and diagnostic procedures--the prognosis on treatment 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 for those results is the high incidence of recurrence, either local or widespread. Local recurrence is directly related to the number of undifferentiated cells and to the grade of wall invasion. So any kind of treatment that would diminish the number of undifferentiated cells and the size or the tumor wall penetration certainly would decrease the local recurrence rate, lengthening the interval free from cancer and, perhaps, modifying the long-term survival rate. Between 1978-1996, a total of 287 patients with rectal adenocarcinoma were treated by pre-operative RTD.

Methodology: The same RDT protocol was used in all the patients: 400 cGy, 200 cGy/day, during 4 consecutive weeks (anterior and posterior pelvic fields). 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 incidence of local recurrence diminished after irradiation 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 infiltration of the rectal wall.