Colorectal cancer patients testing positive for Lynch Syndrome on MSI and IHC were most likely to seek genetic counseling when contacted by a genetic counselor.
The most effective method for identifying patients with colorectal cancer who may have Lynch Syndrome was to send results of the microsatellite instability and immunohistochemistry tests directly to the colorectal surgeon and a genetic counselor, and for the counselor responsible for contacting positive patients to recommend genetic counseling, according to the results of a single-center study conducted by the Cleveland Clinic.
The use of this approach resulted in a 100% referral rate for genetic counseling, with 71% of patients attending counseling and 66% undergoing genetic testing. The results of this study were published in the Journal of Clinical Oncology by Charis Eng, MD, PhD, The Sondra J. and Stephen R. Hardis Endowed Chair in Cancer Genomic Medicine at the Cleveland Clinic, and colleagues.
Lynch syndrome is the most common adult-onset colorectal cancer syndrome, occurring in one in 35 colon cancer patients diagnosed. It confers an 85% lifetime risk of colorectal cancer (vs 5% in the general population), 40% endometrial cancer risk (vs 4% in the general population), and 10% ovarian cancer risk (vs 0.5% in the general population).
In 2009, the Evaluation of Genomic Applications in Practice and Prevention recommended that all colorectal cancers be screened for Lynch Syndrome using microsatellite instability (MSI) and immunohistochemistry (IHC). However, methods for implementing this screening approach have not been studied.
Cleveland Clinic has screened colorectal cancer specimens for Lynch Syndrome since 2004, using three methods in the last 8 years. This study examined the rate of referral to a genetic counselor, the rate of attendance to a genetic counselor, and the rate of genetic testing using three approaches:
• Approach 1: Between January 2004 and July 2007, MSI and IHC results went only to the colorectal surgeon and not to a genetic counselor.
• Approach 2: Between August 2007 and June 2008, both the surgeon and a genetic counselor received the results with the counselor e-mailing the surgeon with the patients identified as being appropriate for referral to genetic counseling.
• Approach 3: After July 2008, the surgeon and the counselor received the results and the counselor contacted appropriate patients to facilitate referral to a genetic counselor.
At the end of the study period, 16% of patients screened for Lynch Syndrome had abnormal MSI/IHC results. Using approach 1, 55% of patients with abnormal results were referred for genetic counseling, with 32% of patients undergoing counseling and 26% of patients undergoing genetic testing.
“Implementing even the most rigorous research into routine clinical care is difficult, as approach 1 shows,” Eng said, noting that the results of approach 1 were “a shock.”
“Although the pathologists noted the results of the Lynch tumor screen in their pathology reports, only a small subset of screen positive patients were referred to geneticists by their surgeons of record,” she said.
In contrast, using approach 2, 82% of patients with abnormal MSI/IHC results were referred to counseling with 64% undergoing counseling. Forty-five percent of patients in this group underwent genetic testing.
These are compared with a 100% referral rate, a 71% attendance rate and a 66% genetic testing rate seen with approach 3.
“[Approach 3] takes away the onus of calling screen positive patients out of busy surgeons’ hands and places the responsibility in a cancer genetic counselor’s hands to scan the screen positive list and to reach out to those patients to arrange for their genetics care,” Eng said.
These findings should help other facilities in the implementation of more widespread screening for Lynch Syndrome by allowing them to “leapfrog” to approach 3 used by the Cleveland Clinic.
“Don’t reinvent the wheel. Start with approach 3,” Eng said. “Multidisciplinary care is the best for such individuals and judicious sharing of responsibility by each discipline’s expertise results in success.”