Prevalence of Potentially Pathogenic Germline Variants Among Adult Patients in the Philippines With Solid...

In high-income countries, 2%-10% of tumor genomic profiling (TGP) reports reveal incidental pathogenic germline variants. A third of these patients would not qualify for genetic testing on the basis of current guidelines. Our study determined the prevalence of potentially pathogenic germline variants (PPGVs) in TGP results of adult patients with solid malignancies in the Philippines.

Annotated reports of patients with solid cancers who underwent TGP using FoundationOne or FoundationOne Heme between January 2021 and July 2023 were reviewed. PPGV criteria include having a variant allele frequency of >30% and were categorized as (1) high penetrance gene (HP), founder variant (FV), or variant associated with clinical presentation (VA). Pathogenicity was crosschecked through the ClinVar database.

Of 446 patients, 13 PPGV variants were found in 50 (11.2%) patients at a median age of 60.5 years. Of them, 28 (56%) had HP (BRCA1, BRCA2, MSH2, MSH6, MLH1, RAD51C, RAD51D), 25 (50%) patients had VA (APC, SMAD4, CDH1, CDKN2A, PTEN), and two patients with lung cancer had a FV (EGFR p.Thr790Met). Six patients had more than one PPGV. PPGVs were primarily found in patients with colorectal (42% of 50 patients with PPGVs), breast (16%), ovarian (6%), and lung (6%) cancer (P < .001). HP genes were mostly found in female patients (71.4%; P = .03).

With a PPGV prevalence of 11% in this study, it is important to recognize PPGVs as it can prompt genetic counseling and confirmatory germline testing.