Rectal cancers in patients with familial adenomatous polyposis.

Patients with familial adenomatous polyposis may develop rectal cancer at their initial presentation (primary) or after colectomy and ileorectal anastomosis (secondary). Little is known about whether differences in presentation impact survival. We hypothesize that patients with secondary rectal cancer have better oncologic outcomes. Patients with rectal cancer in the context of familial adenomatous polyposis were classified into 3 groups: known rectal cancer at presentation, incidental rectal cancer unrecognized before proctocolectomy, and rectal cancer diagnosed after ileorectal anastomosis. Primary endpoint was 5-year survival. There were 58 patients, 39 with primary rectal cancer, 5 of which were incidental, and 19 with secondary rectal cancer. Median ages at diagnosis were 32 years (range 14-56) for primary cancer, 35 years (range 22-56) for incidental cancer and 49 years (range 24-66) for secondary cancer (p = 0.001). 76% of those with primary rectal cancer had symptoms, similar to those with incidental cancer (60%) but more than secondary cancer (21%) (p < 0.001). 47% of primary cancers were advanced (stages III and IV) compared to 20% of incidental cancers and 32% of secondary cancers. There was no local recurrence in any patient, but 9 patients had distant recurrences (16% overall). Overall 5-year survival of patients with primary cancer was 72.4%, incidental cancer was 100%, and secondary cancer was 69.7% (p = 0.031). More patients with primary rectal cancer have advanced disease but survival is similar to those with cancer diagnosed on surveillance. More patients with primary rectal cancer have a restorative resection when compared to other groups.