The Cancer Lifetime Assessment Screening Study in Canines (CLASSiC) offered the first interim results from a prospective, multi-center study evaluating next-generation sequencing (NGS)-based liquid biopsy as a longitudinal cancer screening tool in dogs.
The study enrolled 725 presumed cancer-free dogs (most at elevated risk by age or breed) across 24 sites in the US and Canada, testing blood samples for cancer-associated genomic alterations using the OncoK9 assay alongside regular wellness exams.
Of the 419 dogs meeting inclusion criteria for this interim analysis, 51 were newly diagnosed with cancer over a mean observation period of 422 days, for an observed incidence of 12%. The liver, skin, bone, heart, spleen, lung, and lymph nodes were the most commonly affected sites. Among the true positive cases, six had disseminated or metastatic disease, including two dogs with hemangiosarcoma. The test’s observed sensitivity was 56.9%, with a specificity of 98.9% and a positive predictive value of 87.9%.
The most notable finding for early detection is the shift in when cancer was identified. Adding liquid biopsy to routine wellness visits roughly doubled the number of cancer cases detected overall, and increased preclinical detection more than fourfold from 12% with physical exam and history alone to 55% with liquid biopsy included. Among true positives, median time from a positive result to a confirmed diagnosis was 23 days, with 92% diagnosed within six months using standard general practice diagnostics.
The authors note a relevant precedent from the earlier CANDiD validation study: a dog with hemangiosarcoma had detectable tumor-derived cell-free DNA alterations in blood five months before clinical diagnosis. That finding, together with the disseminated hemangiosarcoma cases identified in CLASSiC, reinforces a pattern seen elsewhere in the literature: that hemangiosarcoma, given its aggressive and often clinically silent early course, may be a particularly strong candidate for benefit from blood-based screening approaches, even though this study was not designed to evaluate any single cancer type.
The authors are careful to frame this as an interim analysis with a relatively short observation period, and note that longer follow-up is needed to determine optimal screening intervals and to confirm whether several apparent false positives may in fact represent very early, not-yet-localizable disease.
