[173953328]
Summary: grade 4 rectal ulceration approx 6 months after stereotactic body radiotherapy with space oar gel of unexpected nature. Difficult to discern reason; reporting given unexpected rectal dosimetry / use of gel. Pt is a relatively healthy gentleman diagnosed with prostate cancer who underwent radiotherapy (rt) to prostate 5-6/2019, tolerating well, with use of rectal hydrogel spacer (space oar, boston scientific). At 3-4 months from therapy, initiated grade 1-2 proctitis / tenesmus symptoms unusual for this therapy when get in place and without precursor symptoms. Despite conservative measures (steroid suppositories / creams, dietary change, systemic steroid pulse), worsened to involve frank pain with bowel movements, rectal bleeding and generalized pelvic floor symptoms (showing of urination when straining with negative cystoscopy for cystitis from radiation). By 6 months, admitted to hosp for urgent work up frankly worsening bleeding / pain, with sigmoidoscopy showing a large ulcer in anterior rectum essentially exposing posterior prostate. While bleeding not life-threatening and no infection, the pain and risk of worsening required diverting colostomy with hope to allow rectum to heal conservatively. Analysis of radiation plan, delivery (including portal cone beam images/ shifts), contours was conducted, yielding no aberrant rectal dose, with the dose being far below our institutional constraints based upon approx 10 yrs of prospective trials. In particular, rectal dose was lowered by our routine use of rectal hydrogel spacer since 2015, to address a 6. 6% rate of grade >=3 rectal injury like this with much higher doses to return in early phase i-ii trials. Thus, this grade 4 rectal injury is the first rectal injury >grade 2 in hundreds of pts since introduction of new measures and followed an unusual course. Given anecdotal reports of rectal hydrogel spacer in cases with high grade rectal injury where speculation was made about potential direct rectal wall injury by the gel (ie: the et al bmj case report 2014 https://www. Ncbi. Nlm. Nih. Gov/pmc/articles/pmc4275689, schorghofer et al pro 2019 https://www. Ncbi. Nlm. Nih. Gov/pmc/articles/pmc6419822/), we thus considered the potential for the rectal spacer gel to have contributed and make this report here. We note of course that substantial volumes of data have been published including by our institution on a lack of such events, even when rectal hydrogel spacer infiltrates the rectal wall (fischer-valuck et al radiat oncol 2019 https://www. Ncbi. Nlm. Nih. Gov/pubmed/28089528). With that said, i felt he need to report this event due to: a) the highly unusual nature and severity of the rectal injury despite low radiation dose to rectal wall/lack of pt co-morbidities; b) somewhat odd timing with lack of symptoms for months before a swift worsening, starting at a time point (approx 4-5 months from spacer insertion) where the gel would be predicted to start dissolving); c) post-hoc review of the pt's radiation planning mri showing an area of anterior rectal wall infiltration by the gel, with potential sign of delamination. Again this has been commonly seen in our and multiple other institutional experiences without clinical correlation in past, and so this was not at the time felt to preclude therapy; d) lack of imaging / bladder cystitis / acute symptoms to suggest a major failure in radiation targeting. In terms of the gel placement, records and post-hoc review with the pt indicate that there was nothing particularly unusual, and again other than subtle pressure feeling most men have, he reported no pain or major change in life after 30 mins to recover from procedure. Overall, we are considering this a high grade rt proctitis with potential contribution of the spacer, unable to discern what dosimetry or change in technique would have changed outcome. Fda safety report id# (b)(4).
Patient Sequence No: 1, Text Type: D, B5