In an oncology waiting room, a patient scrolls through their phone, watching a video that promises to "defeat cancer" through strict fasting. Nearby, a nurse is preparing chemotherapy. These two worlds—modern medicine and alternative health claims—should remain separate, but they increasingly intersect in the lives of cancer patients. Behind the reassuring screen of social media lies a more complex and concerning reality: some patients adopt unproven practices, which can lead to interrupted treatments, weakened immune systems, and even shortened lifespans. Prolonged fasting and overly strict diets can result in malnutrition, which weakens the body and reduces its ability to tolerate cancer treatments. In some cases, this may lead to lower doses of medication being administered. Dietary supplements, often taken without medical advice, can interfere with the body's ability to process cancer treatments, potentially causing damage to the kidneys or liver. Some alternative practices, such as "cellular deprogramming" or urine therapy, can steer patients away from effective medical care, leaving them vulnerable to harm. One widespread belief, that sugar "feeds" tumors and should be completely eliminated from the diet, is often promoted on forums and social media. While this idea has been widely debunked by science, it continues to spread and become an obsession for some patients. Behind this fear lies a genuine desire to regain control over a disease that feels uncontrollable. However, this can lead to a broader distrust of modern medicine, which some patients view as too chemical or impersonal. This distrust can open the door to dangerous ideas, where diet becomes a substitute for proven treatments. Fasting, in particular, has become an attractive practice for many patients seeking a sense of agency. The idea that depriving cancer cells of food could slow the disease is tempting, but it ignores a basic physiological truth: a body already weakened by cancer and its treatments needs nourishment, not deprivation. Too strict a diet or prolonged fasting can lead to malnutrition, which further weakens the body, reduces treatment tolerance, and may even force patients to pause their treatments to regain strength. This is a paradox, as the goal of these practices is often to better withstand the disease. Dietary supplements, often marketed as safe or beneficial, can also interfere with cancer treatments. Some products are sold by individuals with no medical credentials, and they can cause serious harm, including kidney or liver damage. Other alternative practices, such as misused qigong, urine therapy, or "cellular deprogramming" inspired by the controversial theories of Ryke Geerd Hamer, can lead patients away from effective care. These practices, while rooted in a desire for control, can have serious consequences when not guided by medical professionals. Facing this wave of false beliefs, the solution is not to dismiss patients’ concerns but to engage in open dialogue. Better informing patients, understanding their needs, and rebuilding trust between patients and medical professionals is essential. Behind each unproven diet or supplement, there is often a legitimate fear of suffering. Conventional medicine must recognize this and work to address it, rather than allowing false promises to take root.