Comparison of Germline Genetic Testing Before and After a Medical Policy Covering Universal Testing Among Patients With Colorectal Cancer

Province-Wide Ascertainment of Lynch Syndrome in Manitoba

BACKGROUND & AIMS

We describe the experience of Lynch syndrome (LS) diagnosis in the province of Manitoba, Canada, over the past 20 years.

METHODS

We performed a retrospective review of charts from the provincial Genetics Clinic from January 1, 2000, to May 31, 2023. We extracted data on individuals identified to carry a germline pathogenic or likely pathogenic LS gene variant, the mode of ascertainment, family history, and cascade genetic testing (CGT). Data were stratified and compared before and after the year of implementation (October 2013) of the provincial LS screening program (LSSP) and ascertainment by the LSSP vs clinic referrals (CRs).

RESULTS

Between 2014 and 2021, 50 of 101 (49.5%) index cases were identified by the LSSP compared with 51 of 101 (50.5%) from CRs. The proportion of PMS2 variants was 34% (17 of 50) for LSSP index cases compared with 21.6% (11 of 51) for CRs from 2014 to 2021 (P < .001). Among CRs from 2014 to 2021, 24 of 51 (47.1%) families met the Amsterdam criteria, compared with 11 of 50 (22.0%) for the LSSP (P = .01). CGT occurred among 46.8% (95 of 203; average, 1.9 relatives/index) of first-degree relatives of CR index cases vs 36.5% (84 of 230; average, 1.7 relatives/index) of first-degree relatives of LSSP index cases (P = .03). Daughters were most likely to undergo CGT.

CONCLUSIONS

A tumor screening program is more effective at detecting individuals with lower penetrant gene variants and families who do not meet traditional family history-based criteria. Cascade genetic testing is higher among clinic referrals compared with the screening program. These findings suggest a complementary role of these 2 ascertainment methods for Lynch syndrome.

Microsatellite Instability Is Insufficiently Used as a Biomarker for Lynch Syndrome Testing in Clinical Practice

PURPOSE

The pan-cancer presence of microsatellite instability (MSI)-positive tumors demonstrates its clinical utility as an agnostic biomarker for identifying immunotherapy-eligible patients. Additionally, MSI is a hallmark of Lynch syndrome (LS), the most prevalent cancer susceptibility syndrome among patients with colorectal and endometrial cancer. Therefore, MSI-high results should inform germline genetic testing for cancer-predisposing genes. However, in clinical practice, such analysis is frequently disregarded.

METHODS

A next-generation sequencing (NGS)-based technique was used for MSI analysis in 4,553 patients with various tumor types. Upon request, somatic BRAF gene analysis was conducted. In addition, hereditary testing of cancer-associated genes was performed in MSI-high cases using a capture-based NGS protocol. MLH1 promoter methylation analysis was conducted retrospectively in patients with colorectal and endometrial cancer to further investigate the origin of MSI at the tumor level.

RESULTS

The MSI positivity rate for the entire cohort was 5.27%. Endometrial, gastric, colorectal, urinary tract, and prostate cancers showed the highest proportion of MSI-high cases (15.69%, 8.54%, 7.40%, 4.55%, and 3.19%, respectively). A minority of 45 patients (22.73%) among the MSI-high cases underwent germline testing to determine whether the mismatch repair pathway deficiency was inherited. 24.44% of those who performed the genetic test carried a pathogenic variant in an LS-associated gene. Three MSI-high individuals had non-LS gene alterations, including BRCA1, BRCA2, and CDKN2A pathogenic variants, indicating the presence of non-LS-associated gene alterations among MSI-high patients.

CONCLUSION

Although MSI analysis is routinely performed in clinical practice, as many as 77% of MSI-high patients do not undergo LS genetic testing, despite international guidelines strongly recommending it. BRAF and MLH1 methylation analysis could shed light on the somatic origin of MSI in 42.50% of the MSI-high patients; however, MLH1 analysis is barely ever requested in clinical practice.

Using an anomaly detection approach for the segmentation of colorectal cancer tumors in whole slide images

Colorectal cancer (CRC) is the second most commonly diagnosed cancer in the United States. Genetic testing is critical in assisting in the early detection of CRC and selection of individualized treatment plans, which have shown to improve the survival rate of CRC patients. The tissue slide review (TSR), a tumor tissue macro-dissection procedure, is a required pre-analytical step to perform genetic testing. Due to the subjective nature of the process, major discrepancies in CRC diagnostics by pathologists are reported, and metrics for quality are often only qualitative. Progressive context encoder anomaly detection (P-CEAD) is an anomaly detection approach to detect tumor tissue from whole slide images (WSIs), since tumor tissue is by its nature, an anomaly. P-CEAD-based CRC tumor segmentation achieves a 71% 26% sensitivity, 92% 7% specificity, and 63% 23% F1 score. The proposed approach provides an automated CRC tumor segmentation pipeline with a quantitatively reproducible quality compared with the conventional manual tumor segmentation procedure.

Exploring Stakeholders' Perspectives on Implementing Universal Germline Testing for Colorectal Cancer: Findings From a Clinical Practice Survey

PURPOSE

New guidelines recommend considering germline genetic testing for all patients with colorectal cancer (CRC). However, there is a lack of data on stakeholders' perspectives on the advantages and barriers of implementing universal germline testing (UGT). This study assessed the perspectives of members of the Collaborative Group of the Americas on Inherited Gastrointestinal Cancer (CGA-IGC) regarding the implementation of UGT for patients with CRC, including readiness, logistics, and barriers.

METHODS

A cross-sectional survey was sent to 317 active members of CGA-IGC. The survey included sections on demographics, clinical practice specialty, established institutional practices for testing, and questions pertaining to support of and barriers to implementing UGT for patients with CRC.

RESULTS

Eighty CGA-IGC members (25%) participated, including 42 genetic counselors (53%) and 14 gastroenterologists (18%). Forty-seven (59%) reported an academic medical center as their primary work setting, and most participants (56%) had more than 10 years of clinical practice. Although most participants (73%) supported UGT, 54% indicated that changes in practice would be required before adopting UGT, and 39% indicated that these changes would be challenging to implement. There was support for both genetics and nongenetics providers to order genetic testing, and a majority (57%) supported a standardized multigene panel rather than a customized gene panel. Key barriers to UGT implementation included limited genetics knowledge among nongenetics providers, time-consuming processes for obtaining consent, ordering tests, disclosing results, and lack of insurance coverage.

CONCLUSION

This study demonstrates wide support among hereditary GI cancer experts for implementation of UGT for patients with CRC. However, alternative service delivery models using nongenetics providers should be considered to address the logistical barriers to UGT implementation, particularly the growing demand for genetic testing.

Psychosocial factors impacting barriers and motivators to cancer genetic testing

BACKGROUND

Only a small proportion of patients who qualify for clinical genetic testing for cancer susceptibility get testing. Many patient-level barriers contribute to low uptake. In this study, we examined self-reported patient barriers and motivators for cancer genetic testing.

METHODS

A survey comprised of both new and existing measures related to barriers and motivators to genetic testing was emailed to patients with a diagnosis of cancer at a large academic medical center. Patients who self-reported receiving a genetic test were included in these analyses (n = 376). Responses about emotions following testing as well as barriers and motivators prior to getting testing were examined. Group differences in barriers and motivators by patient demographic characteristics were examined.

RESULTS

Being assigned female at birth was associated with increased emotional, insurance, and family concerns as well as increased health benefits compared to patients assigned male at birth. Younger respondents had significantly higher emotional and family concerns compared to older respondents. Recently diagnosed respondents expressed fewer concerns about insurance implications and emotional concerns. Those with a BRCA-related cancer had higher scores on social and interpersonal concerns scale than those with other cancers. Participants with higher depression scores indicated increased emotional, social and interpersonal, and family concerns.

CONCLUSIONS

Self-reported depression emerged as the most consistent factor influencing report of barriers to genetic testing. By incorporating mental health resources into clinical practice, oncologists may better identify those patients who might need more assistance following through with a referral for genetic testing and the response afterwards.

Frequency of actionable germline pathogenic variants identified through tumor next-generation sequencing in a gynecologic cancer cohort

BACKGROUND

Tumor next-generation sequencing can identify potential germline pathogenic variants associated with cancer susceptibility.

OBJECTIVE

To describe the frequency of tumor sequencing results that met European Society of Medical Oncology (ESMO) recommendations for further germline genetic testing, and the frequency of germline variants among a cohort with gynecologic cancer.

METHODS

Patients with gynecologic cancer who underwent tumor sequencing between September 2019 and February 2022 in a large healthcare system in New York City were retrospectively identified. Eligible patients with suspected germline pathogenic variants on tumor sequencing were identified based on ESMO guidelines. Logistic regression was used to explore variables associated with referral and completion of germline testing.

RESULTS

Of 358 patients with gynecologic cancers who underwent tumor sequencing, 81 (22.6%) had ≥1 suspected germline variant according to ESMO guidelines. Of the 81 patients with qualifying tumor sequencing results, 56 (69.1%) received germline testing: 41/46 (89.1%) eligible patients with ovarian cancer and 15/33 (45.5%) with endometrial cancer. In the endometrial cancer cohort, 11/33 (33.3%) eligible patients were not referred for germline testing and the majority of these patients had tumor variants in genes commonly known to cause hereditary cancer. Of the 56 patients who underwent germline testing, 40 (71.4%) had pathogenic germline variants. In multivariable analysis, race/ethnicity other than non-Hispanic white was associated with lower odds of germline testing referral and completion (OR=0.1, 95% CI 0.01 to 0.5 and OR=0.2, 95% CI 0.04 to 0.6, respectively).

CONCLUSION

Given the high rate of pathogenic germline variant detection and the importance of identifying such variants for both patients and their family, it is imperative that eligible patients undergo germline testing. Additional education for providers on multidisciplinary guidelines and development of clinical pathways to ensure germline testing of suspected pathogenic variants identified on tumor sequencing is warranted, especially in light of the racial/ethnic inequity observed.