Liquid biopsy is rapidly becoming an indispensable tool in the oncologist’s arsenal; however, this technique remains elusive in a publicly funded healthcare system, and real-world evidence is needed to demonstrate utility and feasibility. Here, we describe the first experience of an in-house point of care liquid biopsy program at a Canadian community hospital. A retrospective review of consecutive cases that underwent plasma-based next-generation sequencing (NGS) was conducted. Liquid biopsy was initiated at the discretion of clinicians. Sequencing followed a point of care workflow using the Genexus™ integrated sequencer and the Oncomine precision assay, performed by histotechnologists. Results were reported by the attending pathologist. Eligible charts were reviewed for outcomes of interest, including the intent of the liquid biopsy, results of the liquid biopsy, and turnaround time from blood draw to results available. A total of 124 cases, with confirmed or suspected cancer, underwent liquid biopsy between January 2021 and November 2023. The median turnaround time for liquid biopsy results was 3 business days (range 1–12 days). The sensitivity of liquid biopsies was 71%, compared to tissue testing in cases with matched tissue results available for comparison. Common mutations included EGFR (29%), in 86 lung cancer patients, and PIK3CA (22%), identified in 13 breast cancer patients. Healthcare providers ordered liquid biopsies to inform diagnostic investigations and treatment decisions, and to determine progression or resistance mechanisms, as these reasons often overlapped. This study demonstrates that rapid in-house liquid biopsy using point of care methodology is feasible. The technique facilitates precision treatment and offers many additional advantages for cancer care.

Background/Objectives: Ataxia telangiectasia-mutated kinase is encoded by the ATM gene. This gene is altered in many cancer types; however, it is most relevant for eligibility of poly-ADP-ribose polymerase inhibitor (PARPi) therapy in metastatic castrate-resistant prostate cancer in Canada. Non-benign ATM alterations are relatively uncommon, seen in less than 10% of prostate cancers; however, many of these are variants of uncertain significance with limited evidence of clinical significance or actionability. Methods: To aid in variant classification of next-generation sequencing results, ATM immunohistochemistry (IHC) is performed on patient tumour samples to serve as patient-specific functional evidence for ATM protein loss. Results: ATM IHC demonstrates strong concordance with known loss-of-function variants and copy number losses. Additionally, it can be used to clarify ATM protein loss in cases involving variants of uncertain significance (VUSs) or copy number deletions. Conclusions: Incorporation of ATM IHC into clinical testing for prostate cancer represents a relatively cost-effective orthogonal approach that can rescue poor-quality NGS results and clarify the functional impact of ATM VUSs on protein expression. Overall, this strategy may provide useful supportive evidence in prostate cancer biomarker testing and interpretation.