Informed consent to microsatellite instability and immunohistochemistry screening for Lynch syndrome

Objective: Routine microsatellite instability and immunohistochemistry screening of colorectal cancers can assist in identifying a significant proportion of cancers attributable to Lynch syndrome. This article considers whether it is necessary to obtain patient informed consent for microsatellite instability and immunohistochemistry screening. Results: Although microsatellite instability screening examines genetic features of a tumor, it lacks several important characteristics that typically mandate formal informed consent to genetic testing. Microsatellite instability screening describes discrete tissue samples and does not provide information about the rest of the patient's body or germline. In contrast, immunohistochemistry screening is a proteomic test that may reveal information about the patient's germline. As such, immunohistochemistry screening can be viewed as similar to other forms of genetic testing, in which explicit patient consent is regarded as an ethical prerequisite. Conclusion: There is no ethical requirement to obtain explicit informed consent for microsatellite instability screening of colorectal tumor samples for Lynch syndrome. There is support for obtaining patient consent to immunohistochemistry testing, given its similarities with other genetic analyses for which informed consent is typically deemed necessary. Regardless of which screening test is used, it is important to prepare patients and their families for the possibility of a positive screening test.