Session Item

To prospectively assess the 2-year evolution of intestinal  toxicity (IT) in a large cohort of patients (pts) treated with RT including pelvic nodal irradiation (PNI) for prostate cancer with various intents, with special emphasis on the possible association between acute and late IT.

A registered, prospective, multi-institutional study was activated in 2011 and is currently evaluating dosimetric and clinical predictors of RT-induced IT as measured by means of the Inflammatory Bowel Disease Questionnaire (IBDQ), including 10 Bowel items and their possible detrimental impact on Emotional, Social and Systemic Domains. In the IBDQ scales (range 1-7), lower scores indicate worse situation. This analysis focuses on 348 of the 760 pts enrolled up to October 2019, with complete BOWEL scales at baseline, RT mid-point and end, and 6, 12, 18 and 24 months after RT conclusion. The maximum decrease (=worsening) between baseline and RT mid-point or end (D_Acute) was assessed. Moreover, for each of the 10 Bowel symptoms analyzed, pts with a baseline score ≤4, an indicator of an already compromised situation at RT start, were excluded.

Score frequency, average, and distribution of ∆ relative to baseline for each time point considered  were calculated for the ten IBDQ Bowel items.

For each bowel symptom, pts were split into two subgroups consisting of pts with “mild” (∆_acute > -2) or “severe” acute toxicity (∆_acute ≤ -2), and their average scores over time were analyzed and compared.

An acute worsening of the ten Bowel symptoms that partially persisted without full recovery in the two first years after RT emerged. Figure 1 shows the mean values of the ten IBDQ Bowel items at the different time points. A few Bowel symptoms, such as Gas Passage (IBDQ 17) and Frequent Bowel Movements (IBDQ 1) exhibited a major late deterioration while others, such as Nausea and Feeling Sick (IBDQ 29), remained more stable over time. In any case, all the differences between baseline and 24 months were statistically significant (p<0.05, Wilcoxon rank-sum test).

Importantly, pts with more “severe” acute symptoms had a persistently worse deterioration of Bowel  Domain over time as compared to those men with only “mild” acute IT, with the majority of Bowel symptoms in this latter subgroup showing no significant difference relative to the baseline in first two years after RT: the two significantly different trends over time for Abdominal Bloating (IBDQ 20) as an example, are shown in Figure 2.

Intestinal symptom deterioration after RT including PNI for prostate cancer appears mainly as acute toxicity but often persists, though at a lower level, years after irradiation. Of note, the degree of persistence of IT over time clearly depends on the severity of acute IT, suggesting the need to individuate in a timely fashion men potentially at greater risk of experiencing late IT.

Figure 1

Figure 2