Assessment of patient-reported measures of bowel function before and after pelvic radiotherapy: an ancillary study of the North Central Cancer Treatment Group study N00CA

The Bowel Function Questionnaire (BFQ) has been used in clinical trials to assess symptoms during and after pelvic radiotherapy (RT). This study evaluated the importance of symptoms in the BFQ from a patient perspective. Patients reported presence or absence of symptoms and rated importance of symptoms at baseline, 4 weeks after completion of pelvic RT, and 12 and 24 months after RT. The BFQ measured overall quality of life (QOL) and symptoms of nocturnal bowel movements, incontinence, clustering, need for protective clothing, inability to differentiate stool from gas, liquid bowel movements, urgency, cramping, and bleeding. Bowel movement frequency also was recorded. A content validity questionnaire (CVQ) was used to rate symptoms as "not very important," "moderately unimportant," "neutral," "moderately important," or "very important." Most of the 125 participating patients rated all symptoms as moderately or very important. Generally, patients gave similar ratings for symptom importance at all study points, and ratings were independent of whether the patient experienced the symptom. Measures of greatest importance (moderately or very important) at baseline were ability to control bowel movements (94 %), not having to wear protective clothing (90 %), and not having rectal bleeding (94 %). With the exception of need for protective clothing, the presence of a symptom at 4 weeks was associated with significantly worse QOL (P < .01 for all). The BFQ has excellent content validity. Patients rated most symptoms as moderately or very important, indicating the BFQ is an appropriate tool for symptom assessment during and after pelvic RT.