A device, system and method for tumor detection and/or monitoring is proposed. The proposed device comprises a first analysis unit for analyzing the spatial distribution of the photoplethysmographic, PPG, amplitude of PPG signals obtained from a region of interest, a second analysis unit for analyzing the spatial distribution of arterial blood oxygen saturation obtained from said PPG signals, and an evaluation unit for detecting and/or monitoring a tumor in said region of interest based on said two analyses.