This study reports a novel approach for early detection of malignant cancer cells in human organs using a birefringent photonic crystal fiber (PCF)-based optical sensor with dual demodulation. The PCF injects light into the middle hole, enhancing the radiated evanescent field. Analytes injected through the core cause a wavelength shift, measured by peak or dip shift. The proposed sensor has an optimal sensitivity of −7,940 nm/RIU, −8,265 nm/RIU, −9,747 nm/RIU, −9,006 nm/RIU, and −8,994 nm/RIU by peak shift and −8,745 nm/RIU, −10,728 nm/RIU, −8,721 nm/RIU, −10,113 nm/RIU, and −11,150 nm/RIU by dip shift for CRT-(Cervical tissue), BLD-(Blood), ADG-(Adrenal gland), BRT-(Breast) type-1 and type-2 cells, respectively. The PCF sensor presents a shorter sensing length of 550 µm. Results suggest the sensor is effective in detecting malignant neoplastic cells in earlier stages, making it a promising tool for cancer diagnosis and treatment.