Worsening of 2-year patient-reported intestinal functionality after radiotherapy for prostate cancer including pelvic...

To quantify patient-reported 2-year intestinal toxicity (IT) from pelvic nodal irradiation (PNI) for prostate cancer. The association between baseline/acute symptoms and 2-year worsening was investigated.

Patient-reported IT was prospectively assessed through the Inflammatory Bowel Disease Questionnaire (IBDQ), filled in at baseline, radiotherapy mid-point and end, at 3 and 6 months and every 6 months until 5 years. Two-year deterioration of IBDQ scores relative to the Bowel Domain was investigated for 400 patients with no severe baseline symptoms and with questionnaires available at baseline, 2 years, RT mid-point and/or end and at least three follow-ups between 3 and 18 months. The significance of the 2-year differences from baseline was tested. The association between baseline values and Δ_Acute (the worst decline between baseline and RT mid-point/end) was investigated.

In the IBDQ lower scores indicate worse symptoms. A significant (p < 0.0001) 2-year mean worsening, mostly in the range of -0.2/-0.4 points on a 1-7 scale, emerged excepting one question (IBDQ29, "nausea/feeling sick"). This decline was independent of treatment intent while baseline values were associated with 2-year absolute scores. The Δ_Acute largely modulated 2-year worsening: patients with Δ_Acute greater than the first quartile (Q1) and Δ_Acute less or equal than Q1 showed no/minimal and highly significant (p < 0.0001) deterioration, respectively. Rectal incontinence, urgency, frequency and abdominal pain showed the largest mean changes (-0.5/-1): risk of severe worsening (deemed to be of clinical significance if ≤ 2) was 3-5 fold higher in the Δ_Acute ≤ Q1 vs Δ_Acute > Q1 group (p < 0.0001).

A modest but significant deterioration of two-year patient-reported intestinal symptoms from PNI compared to baseline was found. Patients experiencing more severe acute symptoms are at higher risk of symptom persistence at 2 years, with a much larger prevalence of clinically significant symptoms.