The Occurrence of Colon Cancer in Patients with Known Premalignant Colonic Mucosal Diseases

Abstract

Both ulcerative colitis and familial polyposis are colonic mucosal diseases which are known to predispose to colon cancer. While colonoscopy is an accurate modality used in screening and surveillance for patients with these two diseases, patients continue to present with colon cancer with these known premalignant diseases. This study was conducted to ascertain why patients with known premalignant disease still develop life-threatening colon cancer and to assess the clinical profile and prognosis of patients with known ulcerative colitis (UC) and familial polyposis coli (FPC) who subsequently develop colon cancer. Total colectomy, mucosal proctectomy, and ileoanal pullthrough was performed on 367 patients with UC and FPC between January 1982 and March 1993 at our institution. Of these, 15 had invasive adenocarcinoma of the colon (4.1%) in addition to the primary disease. These 15 patients were studied in detail. The average duration of disease from diagnosis to definitive treatment of cancer was 17 years. Thirteen of the patients in this series had UC (87%), while only 2 had FPC (13%). Colonoscopy was used to make the diagnosis in 11 patients (73%), while the diagnosis was made only at the time of surgery in 3 (20%). Nine of the patients presented with a Dukes' B2 cancer or worse, representing 60% of the series. A high percentage had synchronous invasive cancers in this series—6 patients (40%). Despite the relatively high percentage of advanced cancers in this series, at a mean follow-up of 47.1 months, 14 of the 15 patients are still living. One patient has known recurrent disease while 1 has an elevated CEA with no other evidence of recurrence. Our formal survey demonstrated that many of the patients did not participate in a regular surveillance program. Many were also inadequately informed as to surgical options and deferred surgery because they feared a permanent stoma. We conclude that despite the availability of colonoscopic surveillance (1) colon cancers continue to occur in patients with premalignant colonic mucosal diseases; (2) a high percentage of the cancers are advanced and synchronous cancers; (3) the cancers occur at a much younger age and are evenly distributed throughout the colon; (4) many patients demonstrate poor compliance with regular follow-up, thus contributing to the difficulty with early detection; and (5) patients often are unaware of surgical options and fear having a permanent stoma.