Family History And The Risk Of Colorectal Cancer: The Importance Of Patientsí History Of Colonoscopy

Korbinian WEIGL, German Cancer Research Center (DKFZ), Germany

1 Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany
2 Unit of Genetic Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
3 Department for General, Visceral and Transplantation Surgery, University Heidelberg, Germany
4 Division of Preventive Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany
5 German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany

Background: Studies that examined the risk of colorectal cancer (CRC) for persons with a family history (FH) mainly focused on the absolute number of first-degree relatives (FDR) and did not take personal history of colonoscopy of the study participants (HCS) into account.

Methods: We conducted a population-based case-control study in the Rhine-Neckar region of Germany from 2003 to 2014, including 4,334 patients with a first diagnosis of CRC (cases) and 4,232 subjects without CRC (controls). We used multiple logistic regression analyses to assess the association between FH and risk of CRC with odds ratios (OR) and the resulting 95% confidence intervals (95% CI).

Results: Of 7,469 eligible study participants, a total of 1,408 persons reported a FH of any relative, which was associated with a 41% increase in risk of CRC (OR 1.41, 95% CI 1.25-1.59) after adjustment for sex and age. The OR substantially increased to 1.68 (95% CI, 1.48-1.92) when the model was adjusted for HCS. Irrespective of their FH status, persons with positive HCS had a lower risk for CRC compared to persons without HCS and without family history (OR 0.25, 95% CI, 0.23-0.28 for persons without FH of CRC and OR 0.42, 95% CI, 0.35-0.51 for persons with FH of CRC).

Conclusions: In an era of widespread use of colonoscopy, especially among high risk groups, adjusting for HCS is crucial for deriving valid risk estimates of the role of FH in CRC risk. Colonoscopy effectively reduced most of the excess risk of people with a FH of CRC.

Funding: This work was supported by grants from the German Research Council (BR 1704/6-1, BR 1704/6-3, BR 1704/6-4, and CH 117/1-1), the German Federal Ministry of Education and Research (01KH0404 and 01ER0814), and the Interdisciplinary Research Program of the National Center for Tumor Diseases (NCT), Germany.