Would you offer pelvic re-irradiation in the setting of locally recurrent anal cancer in the presacral region?

Re-irradiation is always tricky. I don't want to miss a chance to help someone, and I really don't want to hurt someone. With re-irradiation, the devil is in the details. If it is small, in a spot where symptomatic toxicity is less likely, and a long period of time has passed since the original chemoradiation, then it is easier to recommend re-irradiation. I also feel that locally progressive recurrence is more morbid than the toxicity of re-irradiation. If they can't do further surgery and systemic therapy is unlikely to control the disease, then I believe it is reasonable to recommend. As you can see, I frequently offer re-irradiation. As for dose & fractionation, there are a lot of options that also depend upon location, size, and timing...

This is a complicated topic with a number of different options. Aggressiveness of treatment relates both to disease status and timing of prior lines of therapy. Also, as Dr. Schroeder and Dr. Horne have pointed out, the size and location of the mass are important. Our preference is to retreat prior to re-resection, and we will typically do that with either 39 Gy in 1.5 Gy BID as per the reference below by Tao or use pulsed low dose rate radiation to 40-50 Gy in 2 Gy fractions (PMID: 32769406). This is usually in combination with capecitabine. However, if this is to be done as definitive therapy, we would either use PLDR to 60 Gy or give 1.2 Gy BID radiation to 55.2 Gy (Sun, Br J Radiol, 2012).