• diabetes
• colorectal cancer
• family history

A population based, cross sectional study from East Anglia showed a relative risk of colorectal cancer of 2.9 in subjects with history of type II diabetes. The association was similar in men and women, but apparently stronger in subjects with family history of colorectal cancer.¹ This confirms previous data indicating that insulin—and its structural homologue insulin-like growth factor-I (IGF-I)—may promote colorectal carcinogenesis,^2–4 although the issue, and any related risk quantification, remain open to discussion.

To provide further information on the issue, we considered data from a case-control study conducted in the Swiss Canton of Vaud. Briefly, between 1992 and 2000 trained interviewers collected information on 286 cases (174 men, 112 women) with incident, histologically confirmed colon or rectal cancer (age range: 26–74; median age 65 years) who had been admitted to the University Hospital of Lausanne, Switzerland.

Controls were 550 subjects (269 men, 281 women) aged <75 years (range, 27 to 74 years; median age 59 years) residing in the same geographical area. They were admitted to the University Hospital of Lausanne for a wide spectrum of acute non-neoplastic conditions unrelated to long term diet modifications, including traumas (33%, mostly sprains and fractures), non-traumatic orthopaedic conditions (31%, mostly low back pain and disk disorders), surgical conditions (19%, mostly abdominal, such as acute appendicitis, kidney stones or strangulated hernia), and miscellaneous other disorders (17%, including acute medical, eye, nose and throat, and skin diseases).

All interviews were conducted in hospital during the admission diagnosis. Sixteen per cent of subjects (16% cases; 15% controls) approached for interview …