Session Item

Micro enemas are used to provide a consistently empty rectum to optimise prostate radiotherapy. They are routinely used for all 20 fractions of prostate radiotherapy at our department. This study aimed to evaluate the impact of using micro enemas for the 1st 10 fractions of radiotherapy compared to using them for all fractions in terms of rectal toxicity and daily plan reproducibility.

Two cohorts of 21 patients (selected consecutively) received 20 fractions of radiotherapy to the prostate using daily CBCT image guidance (n=42). The cohorts undertook different bowel preparation. Group 1 used enemas before all 20 fractions. Group 2 used enemas before the first 10 fractions only. The number of repeat CBCT scans for bowel issues was compared between the 2 groups to check for treatment plan reproducibility. Rectal toxicities graded during week 4 of radiotherapy according to the Common Terminology Criteria for Adverse Events (CTCAE) were also compared between the 2 groups.

Using enemas for the first 10 fractions only did not cause an increase in the number of repeated CBCT scans fractions 11-20 for bowel issues (Group 1 repeat scans: mean = 0.86, standard deviation 1.35, range 0-4;   Group 2 repeat scans: mean = 0.52, standard deviation 1.03, range 0-4 for both groups). Only 1 patient in Group 2 required additional rectal preparation and was given suppositories up to fraction 20.  

The number of patients reporting CTCAE V4 Grades 1-2 for colitis, diarrhoea, nausea, proctitis and rectal pain was equal between the 2 groups. The number of patients reporting CTCAE V4 Grades 1-2 for anal / rectal bleeding in group 1 was significantly higher than group 2 (Group 1: n=5, Group 2: n=1). The patient in Group 2 who required daily suppositories to achieve an empty rectum was the only patient in that cohort who reported CTCAE V4 grade 2 anal/rectal bleeding.

The number of repeated CBCT scans at fractions 11-20 for bowel issues were similar between groups.  This demonstrates that enemas are not necessary to improve plan reproducibility for fractions 11-20 for the majority of patients undergoing radiotherapy to the prostate.   Reducing enema use from 20 to 10 fractions resulted in fewer patients experiencing anal / rectal bleeding at week 4 of radiotherapy.  In conclusion, enemas for fractions 11-20 should not be given routinely to all patients as they do not improve plan reproducibility and may increase anal / rectal bleeding.