Proponents of alternative diets claim that life prolongation through adherence to a particular diet is an achievable goal for cancer patients. However, a systematic review based on evidence found indicates that there is no diet regimen that has been conclusively proven to cure cancer or significantly prolong the life of cancer patients.
Gerson regimen — Hildenbrand et al (1995) analysis reported a six-fold increase in five-year survival rates of melanoma patients treated with the Gerson diet (a low sodium, high potassium, lactovegetarian diet that emphasizes fresh vegetables, fruit juices, and vitamin supplements), but the flawed methodology limits the reliability of this study. Therefore, no good evidence supports this approach.
Macrobiotic diets — Based on Carter et al (1993), scientific evidence of benefit from a macrobiotic diet (a high-complex carbohydrate, low fat vegetarian diet) in cancer patients is limited to two methodologically flawed retrospective studies; no controlled trials are available. In addition based on Downer et al (1994), one-third of cancer patients on a macrobiotic diet experience problems due to weight loss, the restrictive and unpalatable nature of the regimen, time spent preparing the food, and the expense and inaccessibility of some ingredients.
Kelley-Gonzalez regimen — The Kelley-Gonzalez regimen refers to a program of dietary restriction, intake of digestive aids (eg, pepsin and pancreatic enzymes), and a "detoxification" regimen that includes frequent coffee enemas. Gonzales et al (1999) studied 36 patients with unresectable or incompletely resected pancreatic cancer, only 11 were considered assessable for outcome for various reasons. The median survival of treated patients was 17 months, compared to a literature control of four to six months. A trial comparing this therapy with gemcitabine for pancreatic cancer was underway at Columbia University, but accrual issues forced a redesign of the study, which now compares outcome in patients who elect to receive the Gonzalez regimen with an externally matched group who receive standard gemcitabine-based combination chemotherapy.
Selected vegetables and herb mix — Selected vegetables and herb mix is a blended, boiled, and freeze-dried product containing ingredients with purported immune-stimulatory and anticancer properties: soybeans, mushrooms, mung beans, red dates, scallion, garlic, lentils, leek, hawthorn fruit, onion, ginseng, angelica, dandelion, senegal root, licorice, ginger, olives, sesame seeds, and parsley. In a matched-control study involving patients with stage III/IV non-small cell lung cancer (NSCLC), median survival duration among the 11 patients who ingested selected vegetables daily was three-fold longer than that of 13 patients who did not receive the supplement (15 versus 4 months). A similar suggestion of prolonged survival was noted in a second study of 18 patients with stage III/IV NSCLC who had either rejected or failed to respond to conventional therapies. The median survival was 33.5 months for the 12 patients who used selected vegetables for two months or longer, and at five years, 50 percent of the patients remained alive.