Cancer Antigen 15-3 and Carcinoembryonic Antigen Chemotherapeutic Response and Associated Hepato-Renal Toxicity in Cameroonian Cancer Patients

Background: Chemotherapy remains central to cancer management in sub-Saharan Africa but is frequently complicated by treatment resistance and cumulative hepato-renal toxicity. Longitudinal biomarker monitoring may improve early detection of subclinical organ dysfunction and therapeutic response. This study evaluated longitudinal changes in hepatic, renal, inflammatory, and tumor-associated biomarkers to elucidate chemotherapy response and resistance patterns among cancer patients receiving systemic therapy in Cameroon. Materials and Methods: A longitudinal observational study was conducted among 120 cancer patients treated at the Cameroon Oncology Centre (February-July 2025). Serum liver enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT)), albumin, urea, creatinine-derived estimated glomerular filtration rate (eGFR), C-reactive protein (CRP) measurement was done once at the end of the chemotherapeutic period were measured at baseline and over three follow-up time points at two-month intervals, while cancer biomarkers, namely carcinoembryonic antigen (CEA), and cancer antigen 15-3 (CA15-3) were screened within two interval periods. Non-parametric analyses (Kruskal–Wallis, Friedman tests) assessed group differences and monotonic trends, while Spearman’s correlation evaluated treatment–biomarker associations. Results: Participants were predominantly female (77.5%), with advanced-stage disease (Stage III–IV: 59.2%). Liver enzymes remained largely stable throughout follow-up, indicating preserved hepatocellular integrity. In contrast, albumin exhibited a significant monotonic decline (−1.20%, <i>p</i> = 0.004), reflecting cumulative metabolic and inflammatory stress. Renal function showed a modest but significant decline in eGFR (−3.77%, <i>p</i> = 0.044), particularly among platinum-based regimens, despite stable urea levels. Tumour marker analysis revealed a pronounced and consistent reduction in CA15-3 (−12.98%, <i>p</i> = 0.006), whereas CEA showed no significant longitudinal trend. Drug-specific correlations supported time-dependent renal and hepatic effects, particularly with cisplatin and combination therapies. Conclusion: Longitudinal biomarker profiling reveals subclinical renal stress, systemic metabolic burden, and differential tumour marker responsiveness during chemotherapy. CA15-3 and eGFR emerged as sensitive indicators of treatment response and toxicity, underscoring the value of integrated biomarker monitoring in resource-limited oncology settings.