FEBRUARY 2024: Cancer Prevention

Lifestyle Choices and Cancer Prevention

Dhwani Patel, Ching Yung Yuan, Mackenzie Smith
February 2024

Cancer is a devastating disease affecting millions of people worldwide. In fact, it is estimated that 2 in 5 Canadians will be diagnosed with cancer in their lifetime (1). To lower our risk for cancer, it is important to understand that cancer is a multifaceted disease with many underlying causes. Most often people tend to attribute cancer solely to genetics, believing that their onset of cancer has been inherited from their parents (1). While genetics does play a role in cancer, only about 5-10% of cancers are caused by inheriting a genetic mutation (1). Thus, it is important to acknowledge the combined role of other factors including lifestyle choices such as diet, exercise, substance abuse, and chronic stress in increasing our risk for cancer. 

Chronic Stress

Chronic stress has been shown to increase an individual’s risk for cancer (2). Many different stressors can cause a state of mental, physical or emotional tension in an individual which is attributed to cancer (2). Some of these stressors may include work, financial stress, difficult life events and discrimination, which all ultimately lead to weakening of our immune system through ways such as chronic immune stimulation, ultimately leaving us susceptible to certain diseases (2). While there are studies that directly associate stress with a higher incidence of cancer, it is important to note that stress can indirectly be linked to cancer risk such as being more likely to develop unhealthy lifestyle factors while under stress such as smoking, overeating and alcohol consumption (2). This shows how engaging in certain lifestyle choices can put our bodies at a higher risk for cancer, especially when in combination with genetics and other factors. 

There are many ways to cope with stress to lessen symptoms and the emotional toll it has on the body. Seeking help through therapies such as psychotherapy and cognitive therapy, as well as support groups can help one to successfully manage their stress (2). In fact, one study showed that engaging in social support services lowered stress-related hormones involved in tumour progression in ovarian cancer patients (2). In addition, doctors often recommend physical activity to reduce depression and anxiety (2). In more severe cases, antidepressants and other medications can be used to treat stress and other psychological disorders, however, it is important to discuss these options with your physician. 

Nutritional Intake and Physical Activity

Diet and physical activity play an important role in cancer risk, aiding in the prevention of both cancer incidence and recurrence (3). There is a consensus across literature describing the lifestyle choices that can prevent cancer; proper diet and regular exercise (3,4). There is also an association between obesity and increased cancer risk (4). It is important to understand the biological relationship between food, exercise, obesity and the development of cancer to support personal lifestyle choices. 

Diet 

Diets abundant in vegetables, fruits, whole grains, fibre, olive oil, and nuts, with a small number of high-cholesterol processed foods, animal products and saturated fats, are associated with lower cancer risk (4). These foods are considered “cancer-preventing” due to their high antioxidant, fibre, and micronutrient content that promotes metabolism and reduces oxidative stress (4). Oxidative stress is when there is an imbalance of reactive oxygen species, harmful oxygen molecules called free radicals, and antioxidants, resulting in DNA damage of healthy cells and mutated cells being able to evade immune destruction (3). This results in cancer incidence and progression. Foods such as colourful fruits, berries, leafy greens, cruciferous vegetables (ex. broccoli, cauliflower, cabbage), high-fibre whole grains (ex. whole wheat bread, brown rice, oats, quinoa), fish that are high in omega-3 fatty acids (ex. salmon, sardines, mackerel), and nuts and seeds high in health fats and antioxidants are also considered to assist in preventing cancer recurrence (4). Weight loss is a characteristic symptom of cancer progression as the cancerous cells outcompete healthy cells for nutrition (4). To mitigate this imbalance, nutritional therapy, a diet plan high in “cancer-preventing” foods, is recommended for cancer patients who have just undergone chemotherapy, in an attempt to improve their nutritional intake, health, and quality of life (4). Many studies show a reduced recurrence rate following adherence to a diet with excessive fruits and vegetables (4). Along with antioxidants, fruits and vegetables are abundant in vitamins C, B, and E, which are anti-inflammatory and enhance the immune system, ultimately empowering the body to prevent cancer (4). 

In contrast, foods that are high in cholesterol and processed fats, such as red and processed meats, heavily salted foods, and low-fibre foods, are associated with increased cancer risk (4). High cholesterol and high-fat foods increase low-density lipoprotein, or LDL cholesterol content, in blood circulation, causing plaque buildup in blood vessels and increasing the risk of cardiovascular disease (3). LDL cholesterol is also known as “bad cholesterol” as it promotes plaque buildup and chronic inflammation (3). This prolonged state of inflammation increases the risk of developing cancer (4). As such, heart disease and stroke are highly associated with the risk of cancer development and are also a common symptom in cancer patients (4). To reduce the chances of developing cardiovascular diseases, diets rich in omega-3 fatty acids are recommended as they reduce inflammation and increase high-density lipoproteins, or “good cholesterol” that can remove excess LDL cholesterol from circulation (4). Additionally, “bad” fats, such as saturated and trans fats are found to increase disease risk even in the smallest quantities (4). This is because they contribute to an increased risk of obesity. Due to trans fats being derived from partially hydrogenated oils, oils that are chemically altered to mimic unsaturated fats to extend their shelf life, our bodies cannot break them down as efficiently to be used as an energy source. Instead, foods with high amounts of trans and saturated fats are converted to stored fat during digestion (4). 

In summary, there is no specific food that is “cancer-preventing”, however incorporating any of the healthier foods mentioned into regular diets, and switching out carcinogenic foods for healthier alternatives, such as using recipes that use white meat instead of red meat, could significantly reduce the risk of developing cancer. 

Physical Activity 

Regular physical activity, such as daily walking, running, playing sports, around 150 to 300 minutes of moderate-intensity aerobic exercises, 75 to 100 minutes of vigorous-intensity aerobic exercises, or at least 2 days a week of muscle-strengthening workouts, is recommended for all ages to maintain a healthy lifestyle that also prevents cancer (4,5). Exercise has many physiological benefits such as reducing insulin resistance and inflammation, mediating cellular damage, and enhancing the immune system (6). In addition, its benefits in healthy weight loss and strengthening cardiovascular functions allow it to be a major determinant of a healthy lifestyle (4). Studies have shown that sedentary lifestyles increase the risk of cancer incidence, progression, and poor prognosis (4). 

In summary, it is recommended that proper diet and exercise are imperative to reduce the risk of cancer and other chronic diseases.

Substance Use

Although substance use and substance abuse denote varying levels of dependency, any recreational usage of cigarettes, alcohol, and/or vaping carries an associated health risk. This is especially evident over long periods of time, where the chemicals resulting from substance usage have time to accumulate within the body and cause cellular changes that are associated with cancer. 

Smoking and Vaping 

The number one cause of lung cancer is currently tobacco (7). Both firsthand smoke and secondhand smoke can contribute to the development of disease (8). Within tobacco smoke, some 7000+ chemicals have been identified, out of which 70 compounds have been proven to lead to cancer (8). Lungs are the first site of exposure to cigarette smoke, and therefore the impact of these carcinogenic (cancer-causing) chemicals is most obviously seen in the lungs (8). However, when the chemicals are absorbed into the body, they can also accumulate elsewhere and contribute to other cancers such as cancer of the mouth and throat, stomach, colon, rectum, liver, pancreas, kidney and cervix (8). 

Figure 1. How the body reacts to short-term and long-term exposure to cigarette smoke, is depicted as cell-level changes (8). 

Figure 2. Harmful compounds found in cigarette smoke. 

When it comes to quitting smoking, there is a common misconception about being ‘too late to quit smoking’ (9). The reality is quitting smoking can lead to improvement in health and longevity regardless of when an individual decides to quit (9). Of course, there are more benefits to quitting early, but studies show even quitting at the age of 65 can still lead to a gain of 2–3.7 years in life expectancy relative to continuing smokers (9). 

Current popular trends in vaping have been linked to a variety of shorter-term diseases such as ‘popcorn lung’ (10). However since cancer takes a relatively long time to develop, the trend of vaping has not been around long enough to produce enough measurable data to assess its cancer risk (10). That being said, it is undeniable that vaping introduces harmful chemicals such as diacetyl, formaldehyde, and acrolein, which all cause varying degrees of damage and irritation to the lung tissue (10). Furthermore, the introduction of fumes into the lungs may lead to the deposition of small particles deep in the lungs, which may lead to lung cancer in a similar mechanism as the one that has already been studied for smoking (10). 

Alcohol

Alcohol consumption has been associated with head and neck cancer, esophageal cancer, liver cancer, colorectal cancer, and breast cancer in women (11). More and more research is also drawing a link between alcohol and melanoma as well as prostate and pancreatic cancers (11). 

Alcohol may contribute to cancer in various ways. The ethanol in alcoholic drinks is broken down by the body into acetaldehyde, which is a toxic chemical that can damage DNA and proteins (11). Metabolizing alcohol also produces reactive oxygen species that can also cause cellular damage and irritation. Long term drinking habits are a persistent source of cellular damage and irritation, which eventually leads to cellular abnormalities that contribute to a whole host of diseases as well as cancer (11). 

Long-term alcohol consumption also decreases the liver’s ability to break down and absorb vitamins and nutrients that can lower cancer and disease risk (11). For women, increased levels of estrogen hormone within the bloodstream can lead to the development of breast and cervical cancer (11). 

The popular myth regarding the benefits of wine (specifically the chemical resveratrol, found in red wine) as heart-protecting and anti-ageing has long since been debunked (12). Before the 2022 statement from the World Heart Federation, the popular myth that moderate wine consumption has certain health benefits has led to increases in wine consumption with no actual proven health benefit (12).

References 

1. cancer CCS/ S canadienne du. Cancer statistics. Canadian Cancer Society. https://cancer.ca/en/research/cancer-statistics.

2. Stress and Cancer – NCI. https://www.cancer.gov/about-cancer/coping/feelings/stress-fact-sheet.

3. Rock CL, Thomson C, Gansler T, Gapstur SM, McCullough ML, Patel AV, et al. American Cancer Society guideline for diet and physical activity for cancer prevention. CA: A Cancer Journal for Clinicians. 2020;70(4): 245–271. https://doi.org/10.3322/caac.21591.

4. Impacts of nutritive and bioactive compounds on cancer development and therapy. https://www.tandfonline.com/doi/epdf/10.1080/10408398.2022.2062699?needAccess=true.

5. Physical Activity and Cancer Fact Sheet – NCI. https://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/physical-activity-fact-sheet.

6. Anderson AS, Renehan AG, Saxton JM, Bell J, Cade J, Cross AJ, et al. Cancer prevention through weight control—where are we in 2020? British Journal of Cancer. 2021;124(6): 1049–1056. https://doi.org/10.1038/s41416-020-01154-3.

7. What Are the Risk Factors for Lung Cancer? | CDC. https://www.cdc.gov/cancer/lung/basic_info/risk_factors.htm.

8. Prevention (US) C for DC and, Promotion (US) NC for CDP and H, Health (US) O on S and. Cancer. In: How Tobacco Smoke Causes Disease: The Biology and Behavioral Basis for Smoking-Attributable Disease: A Report of the Surgeon General. Centers for Disease Control and Prevention (US); 2010. https://www.ncbi.nlm.nih.gov/books/NBK53010/.

9. Taylor DH, Hasselblad V, Henley SJ, Thun MJ, Sloan FA. Benefits of Smoking Cessation for Longevity. American Journal of Public Health. 2002;92(6): 990–996.

10. What Does Vaping Do to Your Lungs?. https://www.hopkinsmedicine.org/health/wellness-and-prevention/what-does-vaping-do-to-your-lungs.

11. Alcohol and Cancer Risk Fact Sheet – NCI. https://www.cancer.gov/about-cancer/causes-prevention/risk/alcohol/alcohol-fact-sheet.

12. Schutte R, Smith L, Wannamethee G. Alcohol – The myth of cardiovascular protection. Clinical Nutrition (Edinburgh, Scotland). 2022;41(2): 348–355. https://doi.org/10.1016/j.clnu.2021.12.009.