A method for precision cancer treatment by identifying drug resistance is provided. In some embodiments, the method may include: detecting tumor oxygenated perfusion by having a patient breathe air to acquire MRI baseline data； inhalation of hyperoxia gas to generate higher than baseline HbO2 blood circulating in body to acquire MRI enhanced data； the region-of-interest (ROI), which in this case is a tumor volume (V0), and which may be performed by volume contour tracing/region-of-interest (ROI) analysis and 3D tumor volumetry methods； calculating voxel's enhanced signal intensity (Δ；SI)； calculating tumor oxygenated perfusion percentage (OPP %)； selecting different threshold and calculating maps such as a reconstruction OPP % pseudo color map； calculating tumor volume change ratio (Vt %)； overlaying reconstruction OPP % pseudo color map to original images for visualizing tumor response data； drawing or plotting the OPP % and Vt % on a cancer treatment response information diagram, and identifying the type of drug resistance, classifying the drug resistance being caused by poor drug distribution factor or cells-specific factor based on pooled collected data.
