Should rectal spacing only be considered routinely for patients who are at elevated risk of rectal toxicity?

I think some caution needs to be injected here (pun intended) before people decide to make a change in practice based on unpublished data. Let me remind everyone that the devil is in the details of the treatment technique, dose constraints, dose-fractionation schedule, treatment delivery technique, etc used in PACE-B. For example, do you routinely fuse MRI and CT in your planning as was done in PACE-B? Do you mandate re-imaging on treatment if the delivery time is more than 3 minutes, as was done in PACE-B? Do you use the same expansions and dose constraints? Do you use the same total dose (36.25 Gy in 5 fractions?--many people use a higher total dose)? How many prostate SBRTs do you do in a year?

I agree with Dr. @Dr. First Last that rect...

PACE-B (NCT01584258) is a phenomenal study that gives us great information about cure rates and toxicity with SBRT for prostate cancer.

To give what appears to be a grade 2 toxicity (placement of spacer), to reduce grade 2 toxicity seems to be an odd clinical decision, especially when the rates of grade 2 toxicity are so low. In addition, the cost of the spacer remains high.

After speaking to the lead author of PACE-B and also GU specialist at Tata Memorial Hospital in Mumbai, I also treat without spacer.

This is cost-effective, reduces unnecessary painful/costly procedures that have risk and when the treatment is done in a high-quality manner such as how they did in PACE-B, patients have excellent outcomes.

Drs. Alison Tree and Vedang Mur...

I'm glad to see the discussion started on this subject. In my opinion, there is no role for Space OAR in prostate radiotherapy other than creating financial toxicity to patients in addition to the inherent toxicity of the procedure in itself. We have to be honest with ourselves about how often grade 2 rectal toxicity is seen in our own practices prior to considering spacers. In general, grade 2 rectal toxicity is very low with well-planned and well-executed treatment, and there is no added benefit with spacers. In my own practice after treating over 600 patients in the last 10 years, with SBRT or hypofractionation (20-25 fxns), with CBCT for IGRT, with no fiducials nor spacers and, following these patients on regular intervals, grade 2 rect...

We have level I evidence supporting decreased rectal toxicity and decreased rates of erectile dysfunction and as we know, our bladder DVHs improve. Being "honest" with ourselves by looking back at our patients is full of bias and misinformation. Many patients quite like their Radiation Oncologist and are somewhat reticent to discuss urinary toxicity for which they will see their Urologist and likewise will see a Gastroenterologist for their rectal bleeding and increasing bowel incontinence as they age. This is why RCTs with patient-reported toxicity are most objective.

I defy anyone above the age of 70 to have an empty rectum and full bladder on a consistent basis. Arguments to suggest hypofractionated radiotherapy is less toxic to the rect...