How would you manage early-stage low rectal cancer in a patient unable or unwilling to undergo surgery?  

This patient may have multiple non-TME alternative options. Trans-anal excision with or without post-op CRT based upon pathological risk factors would be one option. Alternatively, CRT as part of a non-operative management/watch and wait strategy is also associated with favorable outcomes. Here are ...

Interestingly, endocavitary radiation therapy can be curative for rectal adenocarcinomas but also is effective for treating larger villous adenomas that cannot be resected due to comorbidities or patient preference.Kovalic et al., PMID 3338947.

Endocavitary RT a la Jean Papillon and Jean Pierre Gerard.