<p>Cancer remains one of the most critical global health challenges, where early detection significantly improves treatment outcomes and survival rates. This study presents a two-dimensional photonic crystal-based nanocavity sensor designed for the high-precision differentiation of six distinct cancer types from normal cases. The sensor leverages advanced optical signal processing through a carefully optimized nanocavity structure, enabling enhanced light confinement and analyte interaction. The results demonstrate that the sensor achieves exceptional refractive index sensitivity and ultra-low detection limits, making it highly effective for detecting biomolecular variations associated with malignancies. The methodologies employed include rigorous simulations to optimize the sensor’s structural parameters, such as the rod radius, lattice constant, and sample rod dimensions, to enhance performance metrics like the quality factor, sensitivity, detection limit, and figure of merit. The results demonstrate that the proposed sensor achieves exceptional performance, with a sensitivity of 457.1&#xa0;nm/RIU, a maximal figure of merit of 22,856.7 RIU⁻¹, and a quality factor of 54,669. Additionally, the sensor exhibits a minimal detection limit of 4.3 × 10⁻⁶ RIU, showcasing its ability to identify various cancer types with high accuracy. Its compact design and compatibility with on-chip integration facilitate practical implementation in biomarker detection and early cancer diagnostics. A comparative analysis with existing photonic-based detection technologies underscores the originality and superior performance of the proposed sensor, positioning it as a promising platform for non-invasive, real-time cancer screening.</p>