Knowledge and attitudes about microsatellite instability testing among high-risk individuals diagnosed with colorectal cancer.

For individuals meeting Bethesda criteria for hereditary nonpolyposis colorectal cancer syndrome, the microsatellite instability (MSI) test is recommended as a screening evaluation before proceeding to genetic testing. The MSI test is new to the medical setting, but will be increasingly used to screen patients at high risk for hereditary nonpolyposis colorectal cancer. The main goals of this study were to examine knowledge about and exposure to the MSI test among individuals considering the test, to evaluate perceived benefits and barriers to undergoing the MSI test, and to identify the demographic, medical, and psychosocial correlates of the perceived benefits and barriers to undergoing the test. One hundred and twenty-five patients completed a survey after being offered the test, but prior to making the decision whether to pursue MSI testing. Results indicated low levels of knowledge about and previous exposure to the MSI test. Participants held positive attitudes about the potential benefits of the test and perceived few barriers to undergoing the test. Motivations were similar to those cited by individuals considering other genetic tests. Participants with nonmetastatic disease, with lower perceived risk for cancer recurrence, and who reported more self-efficacy endorsed more benefits from the test. Higher levels of cancer-specific psychological distress were associated with more perceived barriers to having the test. These findings suggest that individuals considering the MSI test know very little about it but hold positive attitudes about the test's utility. More distressed patients, patients who perceive themselves at higher risk for cancer recurrence, and patients with metastatic disease might be less motivated to have the MSI test.