The availability of a new therapy is often the primary driver for diagnostic adoption. For Lynch syndrome, many at-risk individuals don't get tested because there's no preventative treatment. Newscom believes its therapy will create a strong incentive for genetic testing, mirroring how checkpoint inhibitors drove a 5x increase in MSI screening.

The GOG-B21 trial found that while adding pembrolizumab to chemotherapy benefits the dMMR subgroup, it paradoxically leads to worse outcomes in the pMMR subgroup. This highlights the critical need for molecular testing to avoid potential harm.

Based on translational data from the RUBY trial, experts are most cautious about recommending frontline checkpoint inhibitors for patients in the "No Specific Molecular Profile" (NSMP) subgroup of pMMR endometrial cancer, suggesting this group may not benefit.

While immunotherapy is transformational for DMMR endometrial cancer, its benefit is much smaller for the PMMR majority (two-thirds of patients). This reality requires more nuanced patient counseling and selective use in this population.

Clinicians must recognize that liquid and solid biopsies show significant discordance. ESR1 mutations are more frequently detected in liquid assays, while PIK3CA mutations are more often found in solid tissue. This variability by gene directly impacts the optimal testing strategy for patients.

The RAS/MAP kinase pathway is an "underrecognized" and "underutilized" therapeutic target in endometrial cancers. Despite up to a quarter of these cancers having mutations in pathway genes, clinical focus has often been elsewhere. This highlights a significant, overlooked opportunity for applying RAS-targeted therapies to a broader patient population.

LOH (Loss of Heterozygosity) scores offer a functional assessment of a tumor's DNA repair capability. They are computationally derived to detect a 'scar' of characteristic genomic changes, like copy number alterations, that accumulate when a tumor cannot repair DNA double-strand breaks, going beyond single-gene mutation analysis.

The technology for detecting cancer via cell-free DNA was discovered by accident. During non-invasive prenatal tests, some abnormal results weren't from the baby but from the mother's previously undiagnosed tumors shedding DNA, revealing an entirely new application for the technology.

Dr. Wander notes a strong clinical correlation: a BRCA mutation found on a somatic NGS test with a ~30-60% allelic frequency is very likely germline. However, this cannot replace a dedicated, CLIA-approved germline test for formal diagnosis and family counseling. This distinction is crucial for patient management and has genetic implications for relatives.