Lung cancer is one of the top death-causing cancers.  Current chemotherapy is effective in lung cancer remission, although the side effects are extremely toxic.  Numerous studies report the benefits of eating healthy food to prevent cancer, although studies on the prevention of the recurrence of cancer are limited.  Theoretically dietary changes to reduce the risk of cancer are parallel to the diet to reduce recurrence. Researchers are looking for a correlation between cancer targets and nutritional approaches to reduce toxicity and improve the efficacy of cancer treatment.

 

• Phytochemicals found in plant-based foods have been found to have chemopreventative action.

• Red meat has been found to increase the risk of lung cancer, the studies on processed meats were inconclusive.

• Diets based on vegetables, fruits, fish, and soy have been found to reduce the risk of lung cancer.  

• A lean body creates an anti-cancer environment.

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An integrative approach to cancer treatment is a combination of complementary, alternative, and conventional therapy; suggested treatment after remission. Recurrence of cancer is still likely due to the heterogeneity and propensity for genomic instability of cancer cells.

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Chemotherapy drugs are currently more efficient in reducing tumor size than they have been in the past, often causing remission.  Unfortunately, these same drugs also cause genetic instability in cells other than cancer cells. Chemotherapy drugs are now more toxic, and there is a higher mortality rate as a direct cause of treatment.  Lung cancer is the number one type of cancer-induced death (Sun, Li, Li, Li, & Han 2016). The American Cancer Society (2017) estimates 222,500 new cases of lung cancer in 2017, with deaths of 155,870. The mortality rate for people with lung cancer was 44.7% from 2010 to 2014.  There is little research on lung cancer compared to other types of cancers.

 

There have been many studies that show poor diet, lack of exercise, excessive alcohol consumption, smoking, and infection directly related to cancer.  Research directed at reducing the risk of cancer recurrence through diet is in the infant stage. Theoretically, the lifestyle and dietary changes suggested lowering the possibility of cancer are the same to prevent reoccurrence.

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Foods have many components, including vitamins, nutrients, and minerals that have a synergistic effect on the body.  A healthy dietary pattern high in vegetables, fruits, white meat, fish, whole grains, and low in red meat, high fat, and refined grains create a lower risk of lung cancer (Sun et al., 2016)   Eating healthy can prevent lung cancer from recurring.  

 

The targets for cancer prevention center around DNA.

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• Preventing damage

• Enhancing DNA repair

• Targeting deficient DNA repair

• Impeding centrosome clustering

• Suppression of telomerase activity

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Free radicals damage DNA, and if the repair mechanism is not functioning properly, this can lead to a mutated cell. Centrosome clustering plays a role in chromosomal instability. Telomerase is usually not found in somatic cells; it is a reverse transcriptase that damages DNA. Nutrigenomics looks at the interaction between nutrition and the genome at a molecular level.  

 

Foods containing vitamin B and D, selenium, carotenoids, PARP inhibitors, resveratrol, and isothiocyanates have a therapeutic effect on genome stability and prevent DNA damage (Ferguson et al. 2015).

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Ferguson et al. (2015) conducted a literary review evaluating five priority targets against genomic instability and nutritional approaches.  The five priority targets determined; prevention of DNA damage, enhancement of DNA repair, targeting deficient DNA repair, impairing centrosome clustering, and inhibition of telomerase activity.  The nutritional approaches highlighted include vitamin D and B, selenium, carotenoids, poly ADP-ribose polymerase (PARP) inhibitors, resveratrol, and isothiocyanates.  Nutrigenomics focuses on matching a person’s diet with their genetic makeup to enhance nutrition metabolism and absorption to create genetic stability.  The researchers found that B vitamins maintain the stability of nuclear and mitochondrial genomes, vitamin C and vitamin D are crucial for the maintenance of genetic stability, and antioxidants prevent DNA damage.  They found that the components in plant foods can alter DNA methylation levels that affect genome stability and tumor suppression. 

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Anand et al. (2008) found that diet contributes to 30-35% of all cancer deaths in the US.  Carotenoids, vitamins, resveratrol, quercetin, silymarin, sulforaphane, and indole-3-carbinol have chemopreventative properties, targeting numerous cell-signaling pathways.

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A systematic review and meta-analysis done by Sun et al., (2016) found that red meat, which is from domesticated animals with more red than white muscle fibers, increased the risk of lung cancer.  Beef, pork, lamb, and goat are considered red meat.  Processed meat that has been preserved by smoking, curing, salting, or chemical preservatives, were found inconclusive in the cause of lung cancer.  Cruciferous vegetables, tomatoes, and allium were found to decrease the risk of lung cancer.  Fruits also reduce the risk of lung cancer.  Folates (B9) have a significant role in DNA synthesis and methylation and expression of genes involved in carcinogenesis.   They found that synergistic effects of antioxidants, polyphenols, fiber, and minerals create an anti-cancer environment.

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The American Institute for Cancer Research (2017) reported that nutrients and phytochemicals are antioxidants that prevent cell damage and enable the body to repair cells and stop cancer cells from reproducing.  They suggest a person consume a plant-based diet and be as lean as possible without being underweight to create an anti-cancer environment.  Consumption of nutrition through food as opposed to supplements.

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The Broad Spectrum Approach proposed by Block et al. (2015) is to use chemicals from plants as opposed to current chemotherapy for cancer prevention and treatment.  The USA recently licensed immunomodulatory antibodies to be used for treatment; these have a low response rate.  The researchers propose an integrative approach for cancer treatment, combining complementary, alternative, and conventional treatment.  They suggest the integrative approach for maintenance after conventional treatment.  This integrative approach will not necessarily maintain the remission of cancer due to the heterogeneity and propensity for genomic instability of cancer cells. 

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The targets for cancer prevention center around DNA; preventing damage, deficient repair, impeding centrosome clustering, and suppression of telomerase activity.  Free radicals damage DNA, and if the repair mechanism is not functioning properly, this can lead to a mutated cell.  Centrosome clustering plays a role in chromosomal instability.  Telomerase is usually not found in somatic cells; it is a reverse transcriptase that damages DNA.  Nutrigenomics looks at the interaction between nutrition and the genome at a molecular level.  Foods containing vitamin B and D, selenium, carotenoids, PARP inhibitors, resveratrol, and isothiocyanates have a therapeutic effect on genome stability and prevent DNA damage (Ferguson et al. 2015).

 

Vegetables and fruits contain nutrients that have been found to protect the DNA.  Cruciferous vegetables, such as broccoli, cauliflower, bok choy, and cabbage contain isothiocyanates which have been found effective in reducing the risk of lung cancer by deactivating cancer-causing chemicals (Anand, 2008).  Watermelon, apricot, grapefruit, and tomatoes are high in the carotenoid lycopene which is an antioxidant. Fifty percent of the carotenoids found in human serum are lycopene (Anand, 2008). Lycopene is a reactive oxygen species (ROS) scavenger.  Allium, which includes onions and garlic provides antitumor effects. Cruciferous vegetables, tomatoes, and allium prevent the risk of lung cancer. Foods high in folates (B9), such as asparagus, citrus fruits, avocados, and beans, play a role in DNA synthesis.  A diet rich in these foods will reduce the risk of relapse of lung cancer.

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Flavonoids with chemopreventative effects are resveratrol, quercetin, silymarin, and indole-3-carbinol.  Resveratrol, found in peanuts, grapes, and berries, stop cancer growth and invasion of other tissues.  Quercetin, found in apples, peppers, red wine, and dark cherries is antioxidant and anti-cancer. In vivo studies in animals have shown that quercetin prevents lung cancer (Anand, 2008).  Silymarin found in dried fruit, and milk thistle is an anticancer agent. Indole-3-carbinol which is in cabbage, broccoli, Brussel sprouts, cauliflower, and daikon artichoke induces enzymes that metabolize carcinogens.  In vivo and in vitro studies on the iso Thi thiocyanate, sulforaphane found in cruciferous vegetables discovered that enzymes detoxify carcinogens and cause cell cycle arrest (Anand, 2008).

       

The phytochemicals found in some teas and spices have therapeutic and preventative actions against cancer.  Green tea contains catechins, which prevent and are used to treat cancer. Turmeric contains curcumin which is anti-inflammatory and chemopreventative.  Garlic contains diallyl disulfide which inhibits growth and proliferation in some cancer cells and repairs DNA. Black cumin contains thymoquinone which has antineoplastic activity against various cancer cells.  The capsaicin in red chili has antioxidant, anti-inflammatory, and anti-tumor effects. Fennel which contains organosulfur compound anethole dithiole thione is believed to be chemopreventative against lung cancer (Anand, 2008).    

 

The antioxidants, vitamin E, tocotrienols, phenolic acids, lignans, and phytic acid, found in whole grain foods have been shown to reduce cancers by 30-70%. (Anand, 2008).  Research on the compound genistein found in soy isoflavones may be chemopreventative against lung cancer. Vitamins from fruits and vegetables, especially vitamin C, D, and E are chemopreventative.  Vitamin C has been shown to reduce the risk of lung cancer (Anand, 2008).

 

There are several challenges faced in utilizing the benefits of a healthy diet to prevent the recurrence of lung cancer. Flavonoids, which are phytochemicals, have poor water solubility and are metabolized quickly in the body. There is conflictual evidence between in vitro and in vivo studies on flavonoids.  Researchers are unable to analyze the percentage of components that are found in vitro while doing in vivo studies. Researchers are looking at ways to overcome these barriers. Evidence shows that the quality of phytochemicals consumed in a healthy diet is not sufficient to provide chemopreventative action.

       

The recurrence of cancer after chemotherapy treatment is likely due to the nature of cancer and the additional genomic instability caused by chemotherapy drugs.  The mortality rate for most chronic illnesses has decreased substantially in recent years. Researchers were able to identify and treat the causes of these chronic illnesses.  As researchers gain an understanding of the cause of genomic instability and the components required to create stability, the mortality rate for cancer will decrease.

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There is evidence that a healthy diet can prevent cancer, but there is insufficient research to determine that healthy eating can prevent the recurrence of lung cancer.  Research to determine the biosynthesis and the dosage of phytochemicals for effective chemopreventative effects is ongoing.

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References:

American Cancer Society (2017).  Cancer statistics center – lung and bronchus.  Retrieved 

           from:  https://cancerstatisticscenter.cancer.org/#/cancer-site/Lung%20and%20

American Institute for Cancer Research (2017).  Heal well.  Retrieved from:

            http://www.aicr.org/assets/docs/pdf/education/heal-well-guide.pdf

Anand, P., Kunnumakara, A., Sundaram, C., Harikumar, K., Tharakan, S., Lai, O., …Aggarwal,

            B. (2008).  Cancer is a preventable disease that requires major lifestyle changes. 

            Pharmaceutical Research, 25(9).

Block, K., Gyllenhaal, C., Lowe, L., Amedei, A. R. M., Amin, A., Aquilano, K., … Zollo, M.

            (2015). Designing a broad-spectrum integrative approach for cancer prevention and

            treatment. Seminars in Cancer Biology, 35, 276-304.

Ferguson, L., Chen, H., Collins, A., Connell, M., Damia, G., Dasgupta, S., … Maxwell, C.

            (2015).  Genomic instability in human cancer: Molecular insights and opportunities

            for therapeutic attack and prevention through diet and nutrition.  Seminars in   

            Cancer Biology, 35, 5-24

Sun, Y., Li, Z., Li, J., LI, Z., & Han, J. (2016).  A healthy dietary pattern reduces lung cancer

            risk: A systematic review and meta-analysis.  Nutrients, 8(134). 

            Doi:10.3390/nu8030134

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Kmiller 4/2017