Genomic, Genetic Testing, and Biomarker Literacy

Genomic, Genetic Testing, and Biomarker Literacy

Core Distinction

OCN candidates must separate two terms that patients often use interchangeably. Genomic tumor testing evaluates changes in cancer tissue or circulating tumor DNA that were usually acquired by the tumor. Genetic testing evaluates inherited germline variants present in normal cells and may affect relatives. A tumor BRCA1 alteration, for example, may or may not be inherited; confirmatory germline testing may be needed when criteria are met. The nurse should use precise language because the implications differ for therapy, screening, insurance concerns, and family communication.

Common Test Types

NGS can identify mutations, insertions, deletions, copy number changes, rearrangements, microsatellite instability, tumor mutational burden, and fusions depending on the platform. High-yield examples include EGFR, ALK, ROS1, BRAF, MET, RET, NTRK, and KRAS in lung cancer; ER, PR, HER2, PIK3CA, and BRCA-related findings in breast cancer; RAS, BRAF, HER2, MSI-H, and NTRK in colorectal cancer; and mismatch repair deficiency across several cancers.

Biomarker Purposes

Biomarkers can be diagnostic, predictive, prognostic, pharmacogenomic, or monitoring tools. Predictive biomarkers estimate likelihood of benefit from a therapy, such as HER2 overexpression and HER2-directed treatment. Prognostic biomarkers provide information about disease course regardless of therapy. Nurses should avoid saying a biomarker guarantees response; it may identify likely options.

Germline Testing and Family Implications

Inherited pathogenic variants may increase risk for breast, ovarian, pancreatic, prostate, colorectal, endometrial, gastric, melanoma, endocrine, kidney, or other cancers depending on the syndrome. Examples include BRCA1/2, PALB2, TP53, PTEN, APC, MUTYH, mismatch repair genes associated with Lynch syndrome, CDH1, RET, VHL, and MEN-related genes.

OCN-level nursing responsibilities include collecting a three-generation family history when appropriate, identifying red flags, encouraging genetics referral, reinforcing informed consent, and supporting cascade testing discussions after genetics professionals and providers interpret results.

Family history red flags include cancer at unusually young age, multiple relatives with related cancers, bilateral or multifocal disease, male breast cancer, ovarian cancer, pancreatic cancer, metastatic or high-risk prostate cancer, medullary thyroid cancer, pheochromocytoma, numerous colon polyps, and known familial variant.

Specimen and Result Literacy

Poor tissue quantity, decalcified bone samples, low tumor purity, old specimens, or prolonged processing can limit testing. Liquid biopsy may be preferred when tissue is inaccessible or rapid information is needed, but false negatives can occur when tumor DNA shedding is low. Nurses can coordinate acquisition of outside pathology, confirm whether testing was already done, track pending results, and help prevent treatment delays.

Results may list pathogenic variants, likely pathogenic variants, variants of uncertain significance, negative findings, or insufficient sample. A VUS is not treated like a known pathogenic variant for family testing or major risk-reduction decisions. Nurses should teach patients not to overinterpret online portals before provider or genetics review.

RN Scope and Patient Teaching

Within RN scope, explain test purpose, sample collection, result timing, why results can change treatment planning, and whom to call with questions. Nurses should not independently classify variants, recommend prophylactic surgery, select targeted therapy, or tell relatives they have inherited risk. Escalate when results suggest urgent therapy planning, when a patient misunderstands germline implications, when family history meets referral criteria, or when testing delays threaten timely treatment.