When treating recurrent rectal cancer with re-irradiation using accelerated hyperfractionation (39-45 Gy at 1.2 or 1.5 Gy BID), what normal tissue constraints would you recommend for the bladder and bowel?

We have always been very careful about excluding the small bowel if it has been treated before. The initial experience from Mohuidin et al indicated that chronic diarrhea could happen if small bowel was treated. For this reason we have used smaller 3D treatment volumes but included the sciatic notch bilaterally and 3cm craniacaudal margins and spared the anal canal of possible.

The first step is to obtain the prior dosimetry and review it. If it was preop, it may have been spared and the prior ir...

Try this reference if you really feel the need for OAR constraints (reasonable reference if writing a protocol).

Cai et al., PMID 25497847.

22 patients (took over 5 and 1/2 years for this enrollment) they detail in the article the prior surgeries, prior chemo, prior radiation and its timing (pre-op, post-op, time of recurrence) as well as prior dose and interval between treatment.

Dose was 3900 cGy in 30 fractions (130 cGy BID 6 hr interval)

Target GTV + 2-3 cm margin for PTV

ICRU-83 followed wit...