From Serum Markers to Liquid Biopsy: Precision Monitoring in Breast, Ovarian, Pancreatic, and Prostate Cancers.

This article is a detailed exploration of the clinical utility, strengths, and limitations of traditional serum tumor markers with emerging circulating cell-free DNA (cfDNA) technologies in the monitoring of breast, ovarian, pancreas, and prostate cancers. It highlights how integrated biomarker strategies can advance precision oncology, particularly in the context of hereditary breast, ovarian, pancreas, and prostate cancer syndrome. A review was conducted of current literature and practice guidelines, including the latest updates from the National Comprehensive Cancer Network (NCCN). The clinical performance, diagnostic value, and monitoring roles of serum tumor markers (eg, CA 15-3, CA 125, PSA, CA 19-9) and cfDNA were discussed descriptively across these four malignancies. Emphasis was placed on evidence relevant to hereditary cancer risk assessment, therapeutic decision-making, and disease surveillance. Serum tumor markers remain a cornerstone in oncology nursing practice because of the accessibility and utility in assessing treatment response and tracking disease burden over time. Yet, their limited sensitivity and specificity, especially for early detection, underscore the need for complementary tools. Circulating cell-free DNA (cfDNA) technologies provide real-time molecular information on tumor biology, offering earlier detection of recurrence, identification of germline-related actionable mutations, and dynamic assessment of therapeutic resistance. In hereditary cancer syndromes such as those associated with BRCA1/2, cfDNA has shown value for detecting minimal residual disease, informing targeted therapy selection (eg, PARP inhibitors), and supporting noninvasive longitudinal monitoring across the cancer care continuum. Integrating cfDNA analysis with traditional serum tumor marker monitoring strengthens the ability to perform comprehensive risk assessment, tailor treatment decisions, and refine disease surveillance for individuals with hereditary cancer risk. This combined approach enables person-centered, evidence-based care while educating patients about the purpose and limits of each test, coordinating timely follow-up, and supporting adherence to surveillance protocols thereby ultimately improving outcomes for high-risk populations. Oncology nurses play a critical role in supporting the integration of advanced biomarker technologies into personalized care. Understanding the evolving applications of cfDNA and serum tumor markers is essential for patient education, shared decision-making, and advocacy for equitable access to precision oncology innovations. Nurses are key partners in implementing biomarker-informed care pathways that promote individualized, high-quality cancer care.