Cost-Effectiveness of Screening for Microsatellite Instability To Detect Hereditary Nonpolyposis Colorectal Cancer FREE

Colorectal cancer is cancer of the colon (large intestine) or rectum. Some colorectal cancer is caused by an inherited cancer syndrome called hereditary nonpolyposis colorectal cancer (HNPCC). People in families with HNPCC have a higher than usual risk for colorectal and some other cancers. Genetic testing to detect a predisposition for hereditary colorectal cancer is now possible, but testing for the gene abnormalities (mutations) associated with HNPCC is too expensive to be done on all patients with colorectal cancer. Consequently, the National Cancer Institute (NCI) has published guidelines for looking for HNPCC in patients with new diagnoses of colorectal cancer. The guidelines advise testing only patients who meet clinical criteria that suggest a high risk for HNPCC (for example, one or more first-degree relatives with colorectal cancer or one of the other HNPCC-associated cancers, or young age at diagnosis) and whose tumors also show an abnormality in the DNA known as microsatellite instability. Most olorectal tumors in HNPCC (85% to 90%) have microsatellite instability. However, many patients who have tumors that show microsatellite instability do not have HNPCC. The guidelines recommend doing further genetic testing for HNPCC in patients who meet the clinical criteria and also have microsatellite instability. The reason to look for HNPCC is to identify families that need close screening. The cost-effectiveness of this strategy is not known.

To calculate the cost-effectiveness of the NCI strategy for screening for HNPCC compared with standard care (not screening for HNPCC).

The researchers did not study actual patients. Instead, they used computers to simulate what might happen to a group of “virtual” patients with new diagnoses of colorectal cancer.

The researchers set up a computer model to simulate what would happen to patients with colorectal cancer and their siblings and children if screening for HNPCC was or was not done. They fed information from a variety of sources about the costs, benefits, and risks of screening into the computer model. They then calculated the cost per year of life saved due to early detection of HNPCC by the screening tests.

When only the costs and benefits related to the patients with cancer were considered, screening for HNPCC cost $42 210 per year of life gained. When the costs and benefits that apply to the patients' siblings and children were also considered, the cost dropped to only $7557 per year of life gained. These cost-effectiveness estimates are within the range that U.S. society generally considers acceptable.

Errors in the assumptions that went into the model could influence the results.

Looking for HNPCC in patients with new diagnoses of colorectal cancer seems to be an effective use of health care resources, especially if the benefits that relate to patients' siblings and children are considered.