Gerson’s book  and articles in English [2-4] are primarily reports of the details of the Gerson regimen, supplemented with case reports of patients seen in his clinical practice. His book presents an extended discourse on the empirical and scientific foundation for his treatment regimen and an expansive description of the treatment and diet followed by 50 patients selected from 30 years of clinical practice. Gerson’s published cases encompass a variety of cancer types. The reports are extended case notes, with occasional x-rays of the patients over time. Although some attempt at follow-up is made, it is not systematic and consists chiefly of anecdotal reports and conversations with patients by mail or phone.
A preliminary study conducted between 1983 and 1984 attempted to collect any available retrospective data on three nonallopathic treatments offered in clinics in Tijuana, Mexico: Gerson, Hoxsey, and Contreras. The authors did not have access to medical records and relied on patient interviews for all information. The self-reporting was incomplete and inconsistent, lacking precise information in areas such as how far the disease had advanced. In the Gerson segment, only 18 of the 38 patients stayed in the study for 5 years or until they died; their mean survival was 9 months from the beginning of the study. The other 20 patients were lost to follow-up. At 5 years, 17 of the 18 had died, and one patient with advanced non-Hodgkin lymphoma was alive but not disease free. Overall, this study did not offer meaningful data to support the clinical efficacy of the approaches studied.
A 1990 noncontrolled, self-selected, matched-pairs study conducted in Austria used a diet regimen based on the Gerson therapy to evaluate diet as an adjuvant to surgery. This diet was ovolactovegetarian. The Gerson regimen is basically strictly vegetarian (no eggs or milk) and does not introduce food other than buttermilk until 6 or 8 weeks into the regimen, if at all, depending on the patient.
Two groups of patients who had undergone surgery—18 patients with colorectal cancer with metastases to the liver and 38 with breast cancer —were treated. Each of the two groups was divided into a diet group and a nondiet group. All patients continued with whatever prescribed conventional regimen was required after their surgery. Results in the matched pairs with colorectal cancer showed an increased survival time in three of the nine patients in the diet group (28.6 months) as compared with four of the nine patients (16.2 months) in the nondiet group. In the breast cancer matched pairs, side effects of chemotherapy and pain and pleural effusion were lower in the diet group. No statistically significant information was generated in this small number of patients; however, the authors stated that the diet regimen appeared to have beneficial effects that required further study.
The Gerson Research Organization published a retrospective survival analysis of their melanoma patients treated with the Gerson approach, which was compared with published survival data according to stage. The analysis showed a survival advantage for melanoma patients with stage IIIA disease and stage IV disease with no visceral metastases, who were treated with the Gerson approach. However, there has been no report of a prospective clinical trial confirming the findings of this retrospective analysis.
The study looked at records of 153 patients with stage I–IV melanoma treated with the Gerson diet. Of the 14 stage I–II patients, all were disease-free at 17 years posttreatment; however, this number was too small for a statistical comparison with other cohorts. For stage III patients, the 5-year survival rate was 71% compared with rates of 27% to 42% reported in the literature. The stage IV patients had the largest survival advantage. The 5-year survival rate for these 18 patients was 39%, compared with 6% in the published literature. The analysis did not include 53 patients who were lost to follow-up, which could have influenced the survival comparisons.
A small best-case series  suggests that the evidence presented supports the development and conduct of a more definite clinical study on the Gerson regimen.
No conclusions about the effectiveness of the Gerson therapy, either as an adjuvant to other cancer therapies or as a cure, can be drawn from any of the studies reported above.
- Gerson M: A Cancer Therapy: Results of Fifty Cases and The Cure of Advanced Cancer by Diet Therapy. San Diego, Calif: The Gerson Institute, 2002.
- Gerson M: Effects of a combined dietary regime on patients with malignant tumors. Exp Med Surg 7 (4): 299-317, illust, 1949. [PUBMED Abstract]
- Gerson M: Dietary considerations in malignant neoplastic disease: preliminary report. Rev Gastroenterol 12: 419-25, 1945. Also available online. Last accessed January 6, 2015.
- Gerson M: The cure of advanced cancer by diet therapy: a summary of 30 years of clinical experimentation. Physiol Chem Phys 10 (5): 449-64, 1978. [PUBMED Abstract]
- Austin S, Dale EB, DeKadt S: Long term follow-up of cancer patients using Contreras, Hoxsey and Gerson therapies. J Naturopathic Med 5 (1): 74-6, 1994.
- Lechner P, Kroneberger L Jr: Experiences with the use of diet therapy in surgical oncology. Aktuel Ernahrungsmed 2 (15): 72-8, 1990.
- Hildenbrand GL, Hildenbrand LC, Bradford K, et al.: Five-year survival rates of melanoma patients treated by diet therapy after the manner of Gerson: a retrospective review. Altern Ther Health Med 1 (4): 29-37, 1995. [PUBMED Abstract]
- Molassiotis A, Peat P: Surviving against all odds: analysis of 6 case studies of patients with cancer who followed the Gerson therapy. Integr Cancer Ther 6 (1): 80-8, 2007. [PUBMED Abstract]