Somatic tumor testing implications for Lynch syndrome germline genetic testing.

Area of Science:

• Oncology
• Genetics
• Cancer Research

Background:

• Somatic tumor sequencing is crucial for personalized cancer treatment.
• This sequencing can incidentally detect germline variants linked to cancer predisposition syndromes, such as Lynch syndrome.
• Clinician awareness of this dual implication is not well-understood.

Purpose of the Study:

• To assess the rate of genetics referral for patients with tumor sequencing findings suggestive of Lynch syndrome.
• To evaluate current clinical practices regarding germline testing follow-up for somatic tumor sequencing results.

Main Methods:

• Retrospective chart review of patients undergoing somatic tumor sequencing.
• Identification of patients with Lynch syndrome gene variants or microsatellite instability.
• Analysis of referral rates to genetics services for germline testing.

Main Results:

• Of 6,556 patients, 90 (1.37%) had findings compatible with Lynch syndrome.
• Among 62 patients not previously seen by genetics, 75.8% were not referred for germline testing.
• Of those tested, 30% were positive for Lynch syndrome, with many having Lynch-associated tumor types.

Conclusions:

• A significant gap exists in referring patients for germline testing after somatic tumor sequencing reveals Lynch syndrome indicators.
• There is a critical need for clinical guidelines to standardize germline referral practices.
• Further research on somatic-germline variant correlations is essential for developing these guidelines.