How would you treat synchronous high-risk prostate and rectal adenocarcinomas in an elderly man where the rectal cancer was resected secondary to obstruction (T3N0)?  

Start with androgen deprivation. EBRT 45 to 50.4 Gy at 1.8 Gy per fraction to the pelvis. Boost prostate with brachytherapy if feasible or EBRT to somewhere around 80 Gy depending on the small bowel. Adjuvant chemo is unlikely to be tolerated.

This is a complex case. We have occasionally encountered patients with synchronous rectal and prostate cancers. The patient's case should be reviewed in GI/GU MDT.  If the rectal cancer is already resected, then the patient may benefit from adjuvant chemo or chemorads, based on pathological f...