RecruitingPhase 2Drug trialAmplitude-Modulated Radiofrequency Electromagnetic Fields (AM RF EMF) in Combination With Fruquintinib in Refractory Metastatic Colorectal CancerThe goal of this clinical trial is to learn if adding amplitude-modulated radiofrequency electromagnetic fields (AM RF EMF) to Fruquintinib in metastatic colorectal cancer that has not responded to other standard treatment is: * Effective in improving survival * safe and tolerable