Failure to diagnose colon or rectal cancer is a common cause of malpractice litigation. The most common reasons for law suits include alleged failure to see a cancer at colonoscopy, failure to investigate rectal bleeding, and failure to screen for colon cancer, typically after age 50 (see also “Failure to Screen for Cancer: The Elephant in the Room”).

Huge polyp in cecum seen only when scope is retroflexed upon entering this area of the colon.

Colon cancer is among the slowest growing common adult tumors. There is a prolonged pre-malignant phase when polyps develop, bleed occasionally, and eventually turn into cancer. These characteristics make the missed diagnosis of colon cancer an ideal lawsuit for a plaintiff. There is furthermore a robust literature which shows a dramatically enhanced outcome from colon cancer when discovered during a screening event (i.e., no symptoms) such as colonoscopy.

Assessing colon cancer cases involves first of all an assessment of the key date in question: when should the cancer have been diagnosed? If the allegation is failure to screen that date is not always clear cut and can be many years before the actual diagnosis. Once that date is established one then has to try to assess tumor stage at that time. With colon cancer the first site of metastasis is usually the liver and the size of the liver metastases at diagnosis or thereafter can be crucial in determining the stage at the time of the alleged negligence. Doubling time analysis can occasionally be useful (see page on Doubling Time) in calculating when initial metastasis occurred. Otherwise web-based Adjuvant Online ( has a colon cancer tab that is helpful in assessing prognosis at the time of negligence and at the time of diagnosis. The long premalignant phase (polyp) or colon cancer and its extremely slow growth rate make many allegations of missed colon cancer difficult to refute on proximate cause alone.

The accuracy of colonoscopy is often at issue. Juries believe that colonoscopy should be fool proof but the literature would suggest a 5-10% miss rate, especially for small polyps. The cecum is especially treacherous because it is difficult to get to with the scope and difficult to see because of its complex anatomy (see picture at left).