Predictors of urinary and rectal toxicity after external conformed radiation therapy in prostate cancer: Correlation between clinical, tumour and dosimetric parameters and radical and postoperative radiation therapy.

OBJECTIVE

To determine rectal and urinary toxicity after external beam radiation therapy (EBRT), assessing the results of patients who undergo radical or postoperative therapy for prostate cancer (pancreatic cancer) and their correlation with potential risk factors.

METHOD: A total of 333 patients were treated with EBRT. Of these, 285 underwent radical therapy and 48 underwent postoperative therapy (39 cases of rescue and 9 of adjuvant therapy). We collected clinical, tumour and dosimetric variable to correlate with toxicity parameters. We developed decision trees based on the degree of statistical significance.

RESULTS

The rate of severe acute toxicity, both urinary and rectal, was 5.4% and 1.5%, respectively. The rate of chronic toxicity was 4.5% and 2.7%, respectively. Twenty-seven patients presented haematuria, and 9 presented haemorrhagic rectitis. Twenty-five patients (7.5%) presented permanent limiting sequela. The patients with lower urinary tract symptoms prior to the radiation therapy presented poorer tolerance, with greater acute bladder toxicity (P=0.041). In terms of acute rectal toxicity, 63% of the patients with mean rectal doses >45Gy and anticoagulant/antiplatelet therapy developed mild toxicity compared with 37% of the patients with mean rectal doses <45 Gy and without anticoagulant therapy. We were unable to establish predictors of chronic toxicity in the multivariate analysis. The long-term sequelae were greater in the patients who underwent urological operations prior to the radiation therapy and who were undergoing anticoagulant therapy.

CONCLUSIONS

The tolerance to EBRT was good, and severe toxicity was uncommon. Baseline urinary symptoms constitute the predictor that most influenced the acute urinary toxicity. Rectal toxicity is related to the mean rectal dose and with anticoagulant/antiplatelet therapy. There were no significant differences in severe toxicity between radical versus postoperative radiation therapy.