TECHNICAL FACTORS AFFECTING MORBIDITY IN DEFINITIVE IRRADIATION FOR LOCALIZED CARCINOMA OF THE PROSTATE

Purpose: The impact of some technical factors on morbidity was analyze d in 738 patients with histologically confirmed carcinoma of the prost ate treated with definitive irradiation. Methods and Materials: The re cords of all patients were reviewed, and morbidity of irradiation was evaluated according to severity. All patients were followed up for a m inimum of 3 years (median observation, 6.5 years). Results: The most f requent Grade 2 (moderate) intestinal complication was proctitis, whic h was observed in 5% of the patients, followed by enteritis (1%) and a nal-rectal fibrosis or stricture (about 1%). Incidence of Grade 3 (sev ere) proctitis was less than 1% and small bowel obstruction, 0.2%. One patient developed radiation-induced ileitis complicated with peritoni tis, which was fatal. The most frequent Grade 2 urinary complication w as urethral stricture (5%) and cystitis with significant symptoms or h ematuria (2%). A vesicosigmoid and a rectovesical fistula (.4%) were n oted, which required colostomy. One patient with hemorrhagic cystitis (.2%) required an ileal bladder, and two cases of ureteral stricture ( .3%) required surgical correction. Most cases of Grade 2-3 intestinal or urinary morbidity appeared within 2-5 years after therapy (8% moder ate and 3% severe cumulative intestinal morbidity at 10 years, and 9% and 3%, urinary). The actuarial incidence of rectosigmoid Grade 2 and 3 morbidity was 10% for patients treated to the pelvic lymph nodes and the prostate and 3% for those treated to the prostate only (p = 0.04) . The difference in urinary morbidity in these two groups of patients was not statistically significant. There was also no significant corre lation of morbidity with boost portal size for prostate irradiation. P atients treated with a stationary portal technique that delivered high er doses to the urinary bladder had a significantly greater incidence of urinary morbidity (18% cumulative) compared with patients treated w ith rotational techniques (5%) (p < 0.1). However, patients treated wi th pelvic fields and rotational techniques had a higher intestinal and rectosigmoid morbidity (11%) than patients treated to the prostate on ly (less-than-or-equal-to 5%) (p = 0.05). No statistically significant difference in intestinal or urinary morbidity was related to doses of irradiation (60-70 Gy). Conclusion: Volume treated and, to a lesser e xtent, dose of irradiation at tolerance levels are important factors i nfluencing significant morbidity in patients with carcinoma of the pro state treated with definitive irradiation. With recent advances in thr ee-dimensional (3-D) treatment planning and conformal radiation therap y techniques, it is imperative to precisely determine optimal volumes and doses of irradiation required to achieve the highest local-pelvic tumor control while minimizing morbidity to enhance the role of irradi ation in the management of localized carcinoma of the prostate.