Relying solely on Next-Generation Sequencing (NGS) is insufficient for HER2 testing in biliary tract cancers. Data shows NGS misses up to 15% of patients with HER2 overexpression detected by immunohistochemistry (IHC). Performing both tests is essential to avoid denying patients effective targeted therapies.

While Next-Generation Sequencing (NGS) is routinely performed for young patients with epithelioid sarcoma, experienced clinicians note it seldom uncovers additional actionable mutations. The primary consistent finding is the SMARCB1 loss. This suggests that while NGS is part of comprehensive care, the likelihood of identifying other targetable pathways is currently very low.

ctDNA testing (liquid biopsy) is more effective than tissue biopsy for identifying ESR1 mutations. It samples DNA from all metastatic sites, capturing the disease's genetic heterogeneity and reflecting the most active resistance mechanisms, unlike a single-site needle biopsy which can miss them.

Instead of just measuring the presence or quantity of proteins, new technology analyzes their physical proximity and co-localization on a cell's surface. This protein "geography" creates a unique spatial fingerprint that can more accurately distinguish healthy regenerating cells from residual cancer cells post-treatment.

Clinicians ordering "NGS for lung" often misunderstand that Next-Generation Sequencing alone does not cover all actionable biomarkers, such as PD-L1 or HER2. This requires pathologists to interpret the clinician's intent and order a more comprehensive and appropriate test panel.

Experts believe molecular tests like Decipher and PTEN status are superior to simply counting bone lesions for guiding treatment. While not yet standard practice for all decisions, this represents a significant shift towards using underlying tumor biology to determine therapy, like adding docetaxel.

For post-progression biopsies, which are often small and contain necrotic tissue, institutions may prioritize DNA-based NGS panels. This strategy is based on the rationale that most resistance mechanisms are genetic mutations detectable by DNA sequencing, reserving RNA panels primarily for identifying less common fusion events.

The panel suggests AKT inhibitor trials in prostate cancer have been disappointing due to suboptimal biomarker selection (e.g., PTEN IHC). A similar drug in breast cancer showed significant survival benefit when using a more precise NGS-based strategy, indicating a potential path forward if the right patient population is identified genetically.

Unlike androgen receptor mutations that arise under treatment pressure, PTEN loss is an earlier event. Therefore, tissue from an original biopsy or prostatectomy remains informative for testing PTEN status when a patient relapses with metastatic disease, simplifying the diagnostic process and avoiding invasive re-biopsies.