Primary prevention
Diet or dietary components can be carcinogenic (cancer-causing) as well as protective (protective) factors for tumor disease.Primary prevention involves slowing initiation and promotion by dietary factors. Depending on the stage of tumor development (1st initiation, 2nd promotion, 3rd progression), one arrives at different mechanisms of action associated with nutrition:
- Stage 1 – Initiation
- Antioxidants protect against the effects of free radicals or ionizing radiation. To that, they prevent the formation of carcinogenic compounds, reducing the risk of neoplastic transformation. For example, vitamin C blocks the formation of N-nitrosamines from nitrite in the stomach.
- Folic acid, via methylation of DNA, protects it and reduces its modification.
- Phase 2 – Promotion
- Growth stimulating factors such as energy intake, growth hormones, cytokines are considered promoters.
- Dietary fats appear to act primarily in the promotion phase of carcinogenesis (cancer development). Here, the composition of the fats plays a role. In animal studies, it was shown that vegetable oils with high levels of linoleic acid, an omega-6 fatty acid (contained in safflower, sunflower, corn oil), had a promotory effect.The omega-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), on the other hand, inhibit carcinogenesis.In what way the fatty acids influence carcinogenesis is not yet sufficiently clear. There are many starting points here: Omega-3 fatty acids stimulate intracellular protein degradation. This reduces the incentive for cell division. Also conceivable is a change in the composition of cell membranes, the immune response and / or prostaglandin synthesis.
- In the growth process, carotenoids play an important preventive role. They affect the so-called gap junctions, which connect neighboring cells and are important for intercellular communication.Beta-carotene and vitamin A metabolites are important for the differentiation of cells. Vitamin D also acts through the same receptor.
A recent study shows that carcinogenesis begins before initiation, with the loss of intercellular communication (disjunction). Vitamin D metabolites such as 1,25(OH)2 D (1,25 dihydroxycholecalciferol or active vitamin D hormone) protect against this disjunction of cells. N. B.: The liver metabolizes vitamin D3 (cholecalciferol) to 25 (OH) D, which is then converted by the kidneys to 1,25(OH)2 D (1,25 dihydroxycholecalciferol or active vitamin D hormone).Vitamin D3 is synthesized in the skin by sunlight (UV). Natural sources of vitamin D3 are cod liver oil and egg yolk. The following is a summary of correlations between dietary components and tumor disease:
- High total fat intake is associated with increased incidence of breast, colon, rectal, prostate, and uterine cancers.
- Increased body weight and energy intake are risk factors for breast, colon, prostate, endometrial, cervical/uterine, kidney, and thyroid cancers.
- Alcohol consumption promotes the development of cancer of the lung, breast, oral cavity, esophagus, stomach, pancreas (excessive consumption in this case), colon and rectum.
- Smoked and cured foods are risk factors for esophageal, stomach and pancreatic cancer.
- A negative correlation exists between fruit/vegetable consumption and lung, breast, oral cavity, colon, prostate, cervical/uterine and bladder cancers.
- Dietary fiber protects against colon and rectal cancer.
Numerous studies show that people who eat a diet low in meat and sausage are less likely to develop malignant tumors. This is mainly attributed to the fact that with predominantly ovo-lacto-vegetarian diet more micronutrients and bioactive substances that have anticarcinogenic effects, as well as many fibers are supplied. Consequently, the strategy is to limit consumption of foods with initiators and promoters, and increase consumption of foods with anticarcinogenic effects and antipromoters.
- Moderate energy intake
- Saturated fatty acids ↓
- Arachidonic acid (omega-6 fatty acid) ↓
- Linoleic acid (omega-6 fatty acid) ↓
- Alcohol ↓
- Heterocyclic amines (formed, for example, during grilling) ↓
- Nitrites (contained in cured meat products) ↓
- Vitamin A, beta-carotene and carotenoids, vitamins C and E, selenium and zinc (= antioxidants), vitamin D, folic acid ↑
- Eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) (omega-3 fatty acids) ↑
Note!Adequate calcium intake may prevent colon cancer. Calcium binds carcinogenic (cancer-causing) bile acids in the colon. Furthermore, attention should be paid to a sufficient supply of so-called bioactive substances – especially secondary plant substances. They support the immune system and neutralize carcinogenic substances. There are probably more than 60,000 secondary plant substances.Anticarcinogenic (cancer-inhibiting) effect is assigned to the following substance classes of secondary plant substances:
- Carotenoids: oranges, in yellow and green vegetables (alpha and beta carotene, lutein, zeaxanthin), tomatoes, tomato paste (lycopene).
- Phytosterols: in cold-pressed oils, nuts (pistachios, macadamia, pine nuts, almonds, pecans).
- Saponins: in legumes, soybeans and products.
- Glucosinolates: in mustard, cabbage, horseradish.
- Polyphenols
- Flavonoids: in the skin of red, purple, blue and yellow fruits such as raspberries, blueberries, cranberries, grapes, wine (quercetin), apples, lettuce, red cabbage, green tea.
- Phytoestrogens: in soybeans, -products, flaxseed, rye, wheat bran.
- Protease inhibitors: in legumes.
- Monoterpenes: in citrus fruits, herbs, spices.
- Sulfides: in bulbous plants
Secondary prevention
When a tumor disease is considered cured, the diet aims on the one hand to compensate for the consequences of the tumor disease. On the other hand, the risk of recurrence should be kept low. In this case, the patient should be guided by the procedures and behaviors that apply in the context of primary prevention. Nutritional therapy in tumor diseaseThere is no real “cancer diet”, because malignant cells are independent of regulatory mechanisms and grow autonomously.Approximately half of all tumor patients show disturbances in food intake, food utilization and metabolism. These nutritional problems are either directly caused by the carcinoma or are general, systemic effects of the tumor and the therapy. The primary nutritional goal is to improve general well-being and prevent or treat malnutrition (malnutrition). Other goals include:
- Support of adjuvant therapy during antitumor therapy.
- Ensuring nutrient intake (macro- and micronutrients) in patients with gastrointestinal dysfunction.
- Maintain and support oral food intake as long as possible.
- Increase appetite
- Reduce discomfort from chemotherapy and radiotherapy
Both malnutrition and cachexia have a high impact on quality of life and survival. Up to 50% of tumor patients may be malnourished. 20% of deaths are due to malnutrition alone.In 80% of patients with pancreatic and gastric cancer, significant weight loss occurs before diagnosis.In breast cancer, leukemias, lymphomas and sarcomas in about 30-40% of cases.One third of patients with lung cancer lose circa 5% of their body weight before diagnosis. Cachexia (emaciation) is the most important immediate cause of death in tumor patients. Among these, patients who lost weight before diagnosis had the worst prognosis.Often malnutrition prevents optimal delivery of antitumor therapy. Consequences of malnutrition include:
- Muscle weakness – the respiratory muscles are also affected, pneumonia can develop.
- Immobility – pressure sores and thromboses are the consequences
- Immunodeficiency
- Fatigue and poor general condition
- Weight loss
The nutritional behavior as well as the nutritional status of the tumor patient should be monitored regularly (regular performance of a body analysis) to detect malnutrition as early as possible. Indication for nutritional therapy in case of impending malnutrition.
- Insufficient food intake – < 60% of the daily requirement for more than one week.
- Persistent diarrhea (diarrhea).
- Polychemotherapy
Indication for nutritional therapy for malnutrition.
- Current weight <90% of optimal body weight.
- Unintentional weight loss > 10% in 6 months or > 5% in 3 months.
- Serum albumin (blood protein) < 35 g/dL, transferrin (iron transport protein) decreased.
- Continuous decrease in albumin, cholinesterase (liver enzyme) or transferrin.
- Detection of isolated micronutrient deficiencies (vital substances).
In advanced tumor disease or even with a lack of appetite, as well as problems ingesting larger amounts of food, liquid food concentrates, dietary food (eg, feeding a fully balanced diet for the dietary treatment of persons with catabolic metabolic state – due tounderweight / malnutrition), should be taken to help. In case of weight loss, it should be started early.At the beginning, do not drink more than 200 ml per day, otherwise diarrhea may occur. Later, 600 ml a day can be added without further ado, preferably between the main meals. If oral nutrition can no longer be maintained, the tumor patient must be fed enterally via a tube or parenterally (via the port or Hickman-Broviak catheter). Any loss of body weight already suffered is difficult to regain.
