The Short Version
Extensive peer-reviewed evidence consistently shows that cancer patients who forgo conventional treatment in favor of alternative medicine face substantially higher mortality, with hazard ratios ranging from 2.0 to 5.68 depending on cancer type. The claim is well-supported but slightly overstated: the strongest evidence applies specifically to curable or nonmetastatic cancers, and the survival gap is driven by refusal of proven therapies rather than a demonstrated direct harm from alternative modalities themselves.