Long-term symptoms after external beam radiation therapy for prostate cancer with three or four fields.

The aim of this study was to investigate whether external beam radiation treatment with three or four fields affects the risk of long-term distressful symptoms. The study included 145 patients who had been treated in Stockholm from 1993 to 1996 for localized prostate cancer. Bowel, urinary and sexual function as well as symptom-induced distress were assessed by means of a postal questionnaire 29-59 months after therapy. Among patients treated with a multileaf collimator, defecation urgency, diarrhoea and loose stools were more common after four fields than after three fields, but faecal leakage necessitating the use of pads and distress from the gastrointestinal tract were less common (although not statistically significantly so). Among bowel symptoms, the strongest association with gastrointestinal distress was found for faecal leakage. Three fields without a multileaf collimator entailed a higher risk of defecation urgency than three fields with a multileaf collimator. We conclude that the choice of three or four fields may imply a contrasting risk scenario for defecation urgency or diarrhoea in comparison with faecal leakage.