Technical factors affecting morbidity in definitive irradiation for localized carcinoma of the prostate

The impact of some technical factors on morbidity was analyzed in 738 patients with histologically confirmed carcinoma of the prostate treated with definitive irradiation.

The records of all patients were reviewed, and morbidity of irradiation was evaluated according to severity. All patients were followed up for a minimum of 3 years (median observation, 6.5 years).

The most frequent Grade 2 (moderate) intestinal complication was proctitis, which was observed in 5% of the patients, followed by enteritis (1%) and anal-rectal fibrosis or stricture (about 1%). Incidence of Grade 3 (severe) proctitis was less than 1% and small bowel obstruction, 0.2%. One patient developed radiation-induced ileitis complicated with peritonitis, which was fatal. The most frequent Grade 2 urinary complication was urethral stricture (5%) and cystitis with significant symptoms or hematuria (2%). A vesicosigmoid and a rectovesical fistula (.4%) were noted, 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% moderate 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 correlation of morbidity with boost portal size for prostate irradiation. Patients treated with a stationary portal technique that delivered higher doses to the urinary bladder had a significantly greater incidence of urinary morbidity (18% cumulative) compared with patients treated with rotational techniques (5%) (p < 0.1). However, patients treated with pelvic fields and rotational techniques had a higher intestinal and rectosigmoid morbidity (11%) than patients treated to the prostate only (< or = 5%) (p = 0.05). No statistically significant difference in intestinal or urinary morbidity was related to doses of irradiation (60-70 Gy).

Volume treated and, to a lesser extent, dose of irradiation at tolerance levels are important factors influencing significant morbidity in patients with carcinoma of the prostate treated with definitive irradiation. With recent advances in three-dimensional (3-D) treatment planning and conformal radiation therapy 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 irradiation in the management of localized carcinoma of the prostate.