Would you offer palliative re-irradiation to the sacrum for a patient with a prior history of RT for rectal cancer?

Local recurrence of rectal cancer is still a quite common situation we see in the clinic. Presacral space lesion with sacral involvement is one of the most common scenarios.

As a tertiary center, we have quite a few cases with locally recurrent rectal cancer. All these patients are evaluated by a multidisciplinary team including colorectal surgical team, orthopedic team, radiation oncology team, medical oncology team, urology team, vascular team, and plastic surgical team. If the patient only has local recurrent disease without poor clinical/biological/molecular features (such as bilateral high level nerve involvement, rapid progression not responding to systemic treatment, BRAF mutation, etc...), we have some experience to first start with...

I agree with @Dr. First Last. Multidisciplinary discussion for such a clinical scenario is key. If the patient is determined to be unresectable following the multidisciplinary review, I would offer palliative re-irradiation. I would favor a dose of 30 Gy in 5 fractions, sparing bowel, bladder, cauda equina, and sacral nerve roots as much as possible, but ensuring adequate coverage of the tumor. Smith et al., PMID 33305093 recently published a small retrospective experience using such an approach with favorable local control and minimal toxicity. These are challenging situations, and gaining local control of the tumor is important to prevent local progression and worsening of symptoms. As always, a discussion with the patient about risks vs....

Yes. The prior RT was 5 years ago, and additional RT can usually be done safely. If this is the only site of disease, then an aggressive dose with concurrent drug might be optimal, with consideration of surgery to follow RT/CT. But, the neurological symptoms suggest infiltration of the sacrum so resection alone is likely not optimal. If you have IORT, that might be reasonable to consider as well (i.e., RT/CT, hopefully, see shrinkage, resection if possible, followed by IORT to resection bed).

Regarding dose: if the prior RT was pre-op, the bowel that is now anterior to the sacrum likely was not in that location during the prior RT, so the bowel likely will be OK with the second course of RT. The normal tissue at risk then might be the nerve...

See articles below:

Grønlie Guren et al., PMID 25613395

Youssef et al., PMID 28740875