Section Three: Cancer Survival
Some cancers have a good prognosis, while others have a more aggressive course. For example, a tumor that is small and has not spread to the lymph nodes or other organs is less dangerous than a tumor that is large or has spread. Pathologists check breast cancer cells to see if they have receptors for estrogen or progesterone. If they do, the tumor cells are more mature and slightly less aggressive than if they lack receptors.
Several research studies suggest that nutritional factors can affect the course of cancer. In general, the same factors that increase cancer risk also make a bleaker prognosis when cancer occurs.
In 1963, Ernst Wynder, M.D., observed that, aside from the fact that Japanese women are much less likely than American women to get breast cancer, when they do get the disease, they tend to survive longer.1 Their improved survival is independent of age, tumor size, estrogen receptor status, the extent of spread to lymph nodes, and the microscopic appearance of the cancer cells.2 Subsequent studies examined the role of diet in cancer survival, and several have implicated dietary fat.
A Canadian research study found that post-menopausal women with cancer were more likely to have lymph node involvement if they had a higher intake of saturated fats. Saturated fats are particularly common in dairy products, poultry, red meat, and even fish (between 15-30 percent of fish fat is saturated fat). It is at much lower levels in vegetables, grains, beans, and other plant products.3
Researchers at the State University of New York in Buffalo examined the diets of cancer patients and tracked their longevity. They found that a woman with metastatic breast cancer has a 40 percent increased risk of dying at any point in time for every 1,000 grams of fat consumed monthly.2 To put this in perspective, the monthly fat content of a typical American diet totals about 2,000 grams for a person taking in 1,800 calories per day. For comparison, a plant-based diet prepared without added fat has only about 600 grams of fat per month. If the researchers’ findings hold, this corresponds to a nearly 60 percent difference in the risk of dying at any point.
These figures are rough estimates drawn from large groups of people. For any individual, many factors affect survival, including other parts of the diet. Diets that are high in fiber and carbohydrate (i.e., plant foods) are associated with a better prognosis, while alcohol consumption worsens the prognosis.4 Patients whose tumors have more estrogen receptors (indicating a better prognosis) tend to be those who had consumed more vitamin A.4
Higher body weight is a disadvantage. Among postmenopausal women with breast cancer, in particular, higher body weight is associated with more lymph node involvement, higher rates of recurrence, and poorer survival.3,5-7
More confirmation came from a 1995 study of 698 postmenopausal breast cancer patients published in the journal Cancer. Those who ate the least fat had only half the risk of dying, compared to the other women, and slimmer women had substantially lower mortality than heavier women. Nonsmokers also had better survival than smokers.8
Vegetable-rich diets are low in fat and rich in fiber, complex carbohydrates, and beta-carotene, all of which are associated with a better prognosis. They also promote weight reduction, which, in turn, helps prevent cancer and also improves survival if cancer is diagnosed.3-7
One would expect that diet would affect survival in cancer of the ovary and uterus, given the similarity in the risk factors for these hormone-dependent cancers and breast cancer. Unfortunately, survival in these forms of cancer has not been as extensively studied as in breast cancer.
Diet may influence the course of prostate cancer as well. Cancer cells arise in the prostates of many men in middle and older age. For some, these cancer cells progress slowly, if at all, while others have more rapidly progressing tumors. Dietary factors may be part of the difference.
When pathologists conduct autopsies of men who die from accidents or other causes, they find asymptomatic cancer cells in the prostates of about 13 percent of men in Singapore and 15 percent in Hong Kong. In Sweden, however, the risk of latent cancer cells is 31 percent.9 In many men, these cells never grow into a large tumor and do not affect life or health in any way. However, just as the prevalence of “latent” cancers varies from one country to another, the likelihood that they will turn into symptomatic cancer varies similarly. A man from Sweden is twice as likely as a man from Hong Kong to have cancerous cells in his prostate, but he is more than eight times more likely to die of prostate cancer.9
The same low-fat, high-fiber diet that helps eliminate the hormonal excesses that are linked to a high prostate cancer prevalence may also help improve survival among those who have the disease. Unfortunately, there has not been enough research in prostate cancer patients to know how successful dietary change might be.
In summary, the following nutritional steps should be considered for cancer patients, in addition to whatever other treatments they may be receiving:
- Eliminate fatty foods. Research studies have shown that the most effective way of doing this is to encourage patients to avoid animal products entirely and to keep vegetable oils to an absolute minimum.
- Base the diet on grains, legumes, vegetables, and fruits.
- These same steps, along with regular exercise, will help the patient lose excess weight.
- To insure complete nutrition, it is important to have a source of vitamin B12, which could include any common multivitamin, fortified soymilk or cereals, or a vitamin B12 supplement of 5 micrograms or more per day.
- What kinds of diets are associated with better cancer survival?
- What steps would you recommend to your cancer patients?
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2. Gregorio DI, Emrich LJ, Graham S, Marshall JR, Nemoto T. Dietary fat consumption and survival among women with breast cancer. J Natl Cancer Inst 1985;75:37-41.
3. Verreault R, Brisson J, Deschenes L, Naud F, Meyer F, Belanger L. Dietary fat in relation to prognostic indicators in breast cancer. J Natl Cancer Inst 1988;80:819-25.
4. Holm LE, Callmer E, Hjalmar ML, Lidbrink E, Nilsson B, Skoog L. Dietary habits and prognostic factors in breast cancer. J Natl Cancer Inst 1989;81:1218-23.
5. Newman SC, Miller AB, Howe GR. A study of the effect of weight and dietary fat on breast cancer survival time. Am J Epidemiol 1986;123:767-74.
6. Donegan WL, Hartz AJ, Rimm AA. The association of body weight with recurrent cancer of the breast. Cancer 1978;41:1590-4.
7. Schapira DV, Kumar NB, Lyman GH, Cox CE. Obesity and body fat distribution and breast cancer prognosis. Cancer 1991;67:523-8.
8. Zhang S, Folsom AR, Sellers TA, Kushi LH, Potter JD. Better breast cancer survival for postmenopausal women who are less overweight and eat less fat. Cancer 1995;76:275-83.
9. Breslow N, Chan CW, Dhom G, et al. Latent carcinoma of prostate at autopsy in seven areas. Int J Cancer 1977;20:680-8.