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Nutrition
for Cancer and Aging page 1 2 3 Slide 14-1. Cancer is due to accumulation of DNA mutations that confer a growth advantage and invasive properties on clones of cells. A variety of external factors including nutrients in the environment interacting with genetic susceptibility influence the accumulation of mutations in cells. Nutrition is important at every stage of carcinogenesis from initiation to promotion to progression and metastasis. Slide 14-2. Cancer is the result of the growth of a clone of genetically susceptible cells that have been influenced by the environment including nutrition to outgrow neighboring cells. A growth advantage is obtained either by unregulated proliferation as the result of oncogene expression or inhibited cell death (lack of apoptosis) due to mutated non-functional tumor suppressor genes. Slide 14-3. The primary risk factor for cancer is aging. All data demonstrating nutritional influence utilize age-adjusted cancer incidence. Through primary prevention as well as nutritional effects on patients with early treated cancer, the hope is to reduce the duration of morbidity as well as lengthen survival. This has not yet been demonstrated in clinical trials, but is the ultimate goal of research in nutrition and cancer. Slide 14-4. International correlation data in the late 1960’s demonstrated a relationship of age-adjusted breast cancer incidence to dietary fat intake. This correlation marked a dietary pattern rather than a specific effect of dietary fat. Later studies pinpointed a correlation with meat protein rather than vegetable protein intake. Migration data also demonstrate that individuals moving from a high risk to a low risk country or vice versa take on the risk of the country to which they migrate within one generation. Slide 14-5. International correlation data also show a relationship of adult height to the age-adjusted rate of breast cancer. Adult height is a marker of pre-pubertal nutrition. With an increase in childhood obesity incidence in a country there is a concomitant increase in adult height. The incidences of obesity and obesity-related cancers have increased in Japan in the last twenty years as has adult height. There is evidence that childhood obesity confers a lifelong increased risk of common forms of cancer. Slide 14-6. Obesity is a risk factor for common forms of cancer including breast, prostate, colon, uterine, kidney, gallbladder, and pancreatic. Ad lib intake of excess calories in animal models has also been associated with enhanced tumorigenesis for breast, colon and skin cancer. Since laboratory animals tend to develop obesity with age, the preventive effects of calorie reduction in animals are likely to be analagous to the prevention and treatment of obesity in humans by either reduction in caloric intake or an increase in physical activity. Slide 14-7. An intervention study in humans with non-melanoma skin cancer reveals a striking effect of a high fat (higher calorie) diet on the development of new skin lesions. This is a proof of principle in a clinical trial since the same effect had been seen in the early 1900’s in rodents where a carcinogen was painted on the skin and animals were fed either low fat or high fat diets. Similar proof is not yet available for breast and prostate cancer. Slide 14-8. The trends for major forms of cancer in women is shown here during the past century. Lung cancer has increased as women have begun smoking. Breast cancer incidence and mortality have remained relatively constant despite advances in diagnosis and therapy. There is significant evidence that major forms of cancer are affected by diet and lifestyle. Slide 14-9. The trends for major forms of cancer in men is shown here during the past century. Lung cancer has remained a predominant form of cancer in men. Prostate cancer mortality has remained relatively constant despite advances in diagnosis and therapy. The prostate cancer incidence has increased markedly, so that when mortality is recalculated based on a percentage of diagnosed cases there is an apparent reduction in risk of mortality. However, age-adjusted death rates have remained constant. There is significant evidence that major forms of cancer are affected by diet and lifestyle. Slide 14-10. A number of hormones are affected by a low fat diet fed ad lib, and in this study the levels of the female hormones, estradiol and estrone, involved in breast tumorigenesis are reduced by about 25% in both the follicular and luteal phases of the cycle. This reduction is comparable to the difference in hormone levels observed between Chinese women living in Los Angeles and Shaghai. Since there is a much higher incidence of breast cancer in U.S. Chinese women compared to Chinese women in China, the effects of low fat diet on breast cancer incidence may be mediated by effects of nutrition on reproductive hormone levels. Top of page
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Nutrition
101 - Natural
Remedies - Weight
Management - Physician
Education |
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