Cancers are a major health problem, resulting in one fourth of deaths in the United States. During their lifetime, almost one in two men and more than one in three women will develop cancer. Conventional methods of cancer treatment heavily rely on surgery, radiotherapy (exposure to a radioactive substance) and chemotherapy (injection of highly toxic substances), but all these techniques have significant and potentially harmful side-effects.

New studies are looking into ways to increase patient tolerability in order to raise levels of chemotherapy applied, however, from the American Cancer Society itself, chemotherapy and radiotherapy are known to induce secondary cancers in patients. So why emphasize the toxic route when other options offer so much promise? This first post will discuss nutrients and foods that have been reported as beneficial in cancer prevention, while a second post will present diets that have shown high promises in fighting established tumors.

However, if you or someone you know has been diagnosed with cancer, please remember that it is never recommended to stop medical treatment in order to try a diet modification. It is also always recommended to let your health provider know about any new foods or nutrients you intend to take, since some of them may interfere with conventional cancer treatment.

What is cancer?

Cancer is characterized by uncontrolled  growth and spread of abnormal cells. Although the causes of cancers are still largely unknown, it has been established that cancers involve the malfunction of genes that control cell growth and division. Although about 5% of cancers are considered hereditary, most cancers result from damage to genes, related to internal factors, such as hormones or cell metabolism, or environmental factors, such as smoking, exposure to chemicals, sunlight, or ionizing radiation.

The concept of immunosurveillance describes the capacity of our body to detect precancerous cells, which express markers of genetic irregularities, and to eliminate them. It is therefore suggested that our body not only has the capacity to get rid of cancerous cells, but that it does so all the time.

What are the main types of cancers?

In the United States, prostate cancer is the most common type of cancer, followed by breast cancer, lung cancer, colorectal cancer, melanoma, non-Hodgkin lymphoma, thyroid cancer, kidney cancer, endometrial cancer, leukemia and pancreatic cancer (data for 2013).

How can food fight cancer?

Fighting cancers obviously starts at the preventive level, especially because it is estimated that 30 to 40 percent of all cancers can be prevented by lifestyle and dietary measures alone. Foods and nutrients described below have been shown to exhibit beneficial effects in cancer prevention. Some diet modifications are also showing great promises in reducing tumor sizes, those will be discussed in a second post.

Although it is often difficult to assess the mechanisms by which a specific food or diet exerts its effects on a disease, cancer prevention generally occurs through either the inhibition of the development of invasive cancer by blocking DNA damage or by stopping the progression of tumors after damage has already occurred. Once a tumor is created, its growth and malignancy become highly dependent on the development of new blood vessels or angiogenesis, which allows cancer cells to multiply and migrate to other sites. A recent study details known antiangiogenic molecules and their food sources and explains how these foods may help fight cancer by preventing tumors to grow and spread. The following table summarizes nutrients known to prevent and slow cancer growth, their main food sources and the type of cancers that has been described to benefit to those nutrients.

Anti inflammatory and anti oxidant	Food source	Type of cancer concerned
Insoluble Dietary fibers	Fruits, vegetables, grains	Colorectal, breast
Vitamins A and E combined	Vitamin A: liver, fish, dairy; Vitamin E: wheat germ, almond, peanut	Lung
Vitamin D		Colorectal
Retinoids, carotenoids	Egg yolk, carrots, sweet potato, pumpkin, cantaloupe	Breast, leukemia
S-allylcysteine S-allylmercapto-L-cysteine	Garlic	Colorectal, breast, brain
Antiangiogenic	Food source	Type of cancer concerned
Catechins	Green tea	Colon, prostate lung, esophagus
Genistein	Soybeans	Breast, prostate
Resveratrol	Mulberries, peanuts, grapes, red wine	Breast, skin, lung
Lycopene	Tomatoes, watermelon, papaya	Breast, liver, colon, prostate
Omega-3	Salmon, herring, mackerel, anchovies, sardines, trout	Pancreas, colon, breast, prostate
Glucosinolates	Cabbage, broccoli, cauliflower, collard greens, mustard greens, radishes, Brussel sprouts, bok choy, kale	Lung, pharynx, larynx, esophagus, non-Hodgkin’s lymphoma
Quercetin	Red onion, red apple, capers, plums, dill, kale, buckwheat, watercress, cranberry	Lung, colorectal. Prostate, ovaries, larynx, esophagus, stomach
Anthocyanins	Strawberries, blackberries, grape, red wine	Esophagus
Proanthocyanidins	Cacao, cinnamon, cranberry, apple, grape, black current, chokeberry, persimmon	Liver, prostate, lung, colorectal, larynx, breast, ovary, non-Hodgkin’s lymphoma
Ellagitannins	pomegranate, strawberries, blackberries, raspberries, muscadine grapes, walnuts, and pecans	Prostate, colorectal
Menaquinone	Fermented dairy (cheese, yogurt), fermented soy, dark meat	Lung, prostate
Curcumin	Turmeric spice	Skin, stomach, intestines, liver, colorectal
Beta-cryptoxanthin	Papaya, carrots, sweet potato, pumpkin, cantaloupe	Cervix, lung, gall-bladder, breast

These foods can easily be combined in a cancer-fighting diet. Once a diagnostic of cancer has been made, cancer-fighting foods may also slow cancer progression in conjunction with recommended treatment or may help with recovery. Other diets have also be shown to help shrink tumors. Those will be discussed in a second post.

References used in this article:

Terry P, Giovannucci E, Michels KB, Bergkvist L, Hansen H, Holmberg L, Wolk A. Fruit, vegetables, dietary fiber, and risk of colorectal cancer. J Natl Cancer Inst. 2001 Apr 4;93(7):525-33.

Sánchez-Tena S, Lizárraga D, Miranda A, Vinardell MP, García-García F, Dopazo J, Torres JL, Saura-Calixto F, Capellà G, Cascante M.Grape antioxidant dietary fiber inhibits intestinal polyposis in ApcMin/+ mice: relation to cell cycle and immune response. Carcinogenesis. 2013 Aug;34(8):1881-8. 

Li WW, Li VW, Hutnik M, Chiou AS., Tumor angiogenesis as a target for dietary cancer prevention.  J Oncol. 2012;2012:879623. (link to a video from the same author)

American Cancer Society: Cancer Facts and Figures 2013. Atlanta, Ga: American Cancer Society, 2013. 

Tang ML, Gasser S. ATM activation mediates anticancer immunosurveillance by natural killer and T cells. Oncoimmunology. 2013 Jun 1;2(6):e24438.