Lifestyles and Cancer: A Brief Review

Cancer is a devastating disease. It results in significant physical and mental suffering and gravely affects the financial status of the affected individuals and their families. Practicing healthy lifestyles can prevent many cancers and greatly ameliorate several adverse effects of ten imparted by the disease and its treatment. Healthy lifestyles can also improve the patients’ quality of life and significantly improve outcomes. This brief review looks at the published data on the persuasive benefits of healthy lifestyles on cancer.


INTRODUCTION
(Lauby- . Overweight/obesity accounts for 15.1% of all cancer cases in Scotland and 6.3% of all cancer cases in England (Brown et al., 2015). In Germany, 7% of the cancers were attributable to excess body weight (Behrens et al., 2018). In the USA, 7.8% of incident cancer cases in 2014 were attributed to excess body fatness (Islami et al., 2018). In this study, researchers found that excess body weight was associated with 60.3% of uterine cancers, about one-third of liver cancers (33.9%), 11.3% of breast cancers in women, and 5.2% of colorectal cancers. Several studies have documented treatment-related toxicity, cancer relapse, and decreased survival in obese children Orgel et al, 2014;Amankwah et al, 2016;Orgel et al., 2016) and obese adults (Calle et al., 2003). According to an American Cancer Society study, excess body weight is thought to be responsible for about 11% of cancers in women and about 5% of cancers in men in the United States (Cancer.org, 2020). It is estimated that obesity-related cancer deaths in men and women (combined) account for 6.5% of all cancer deaths (Islami et al., 2018). Obesity plays a negative role in cancer recurrence and the development of second primary cancers (Sang et al., 2016). Obesity also reduces the quality of life in cancer survivors (Rock et al., 2012). According to the American Cancer Society, excess body weight may be responsible for about 11% of all cancers in women and about 5% of all cancers in men in the United States (ACS, 2020).
Obesity contributes to a pro-carcinogenic environment by initiating several sex and growth hormonal changes, producing a pro-inflammatory state, promoting oxidative stress, cell proliferation and angiogenesis, and encouraging inhibition of apoptosis/cell death (Perez-Hernandez et al., 2014;Anderson et al., 2015). Altered gut micro biomes associated with obesity may also play a role (Djuric, 2017).
Smokers often continue to smoke after the cancer diagnosis (Westmaas et al., 2015), especially if their cancer is not smoking-related (Burke et al., 2009;National Cancer Institute, 2020). Continued smoking in these patients increases the risk of a poor treatment response and enhanced treatment-related toxic effects (NCCDPHP, 2014). They demonstrate a higher risk of cancer recurrence (Warren et al., 2019). There is also an increase in the risk of developing a primary second cancer (Do et al., 2004). Non-cessation also deleteriously affects the quality of life (Danson et al., 2016;Jang et al., 2011) and increases mortality (Tao et al., 2013;Travers et al., 2015;Sitas et al., 2014). Studies have estimated that cancer diagnosis associated with smoking cessation reduces the risk of dying by 30% to 40% (Gritz, Toll, &Warren, 2014).
Smoking cessation after cancer diagnosis may have benefits that equal or exceed those achieved by cancer treatments (Toll et al., 2013). Smokers also tend to participate in other unhealthy lifestyle behaviors, such as a high consumption of junk food, decreased levels of exercise, and greater alcohol use (Berrigan et al., 2003;de Vries et al., 2008;Lohse et al., 2016). This not only increases cancer risk and its complications (Lohse et al., 2016;Pronk et al., 2004),but also increases the risk of developing chronic ailments such as cardiovascular and respiratory diseases (NCI, 2017). They also tend to comply less with cancer screening guidelines than never-smokers (Sanford et al, 2019).

Alcoholism
Alcohol intake is common worldwide (Manthey et al., 2019) and remains a major risk factor for cancer (Praud et al., 2016;Secretan et al., 2009). It is a known carcinogen. (Secretan et al., 2009;IARC Working Group, 1988).) Its consumption increases the risk for several cancers (Boffetta & Hashibe, 2006;Bagnardi et al., 2015). It is estimated to be responsible for 6.4% of all cancers in women and 4.8% of all cancers in men (Islami et al., 2018). Esophageal cancer has the strongest association with alcohol intake (Kumagai, et al., 2013). Breast tissue is extremely susceptible to alcohol intake (IARC, 2010) and there is a 7-10% increase in risk for each 10 g (~1 drink) alcohol consumed daily by women (Chen et al., 2011), irrespective of their menopausal state. It is estimated that alcohol consumption is responsible for 4-10% of all breast cancers in the USA (Seitz et al., 2012).Binge drinking increases the risk even moreby 21%, according to the Nurses' Health Study (Chen et al., 2011). Several mechanisms have been attributed to this increased risk of breast cancer (Chen et al, 2011).Abnormal estrogen levels have been associated with breast cancers, and alcohol intake increases circulating sex hormone levels in both premenopausal (Reichman et al., 1993) and postmenopausal women (Dorgan et al., 2001). The proposed mechanisms include increased aromatase activity (Purohit, 2000), decreased hepatic catabolism of androgens (Sarkola et al., 2001), and/or effects on adrenal steroid production (Dorgan et al., 2001) Alcohol intake has also been linked to an increase in several other cancers, such as gastric cancer (Tramacere et al., 2012), colorectal cancer (Fedirko et al., 2011), liver cancer (Bagnardi et al., 2015),prostate cancer (Watters et al, 2010), lung cancer (Bagnardi et al., 2015), and some skin cancers (Rota, 2017). It also increases the risk of an aero digestive-tract cancer (Day et al., 1994).In a review of 222 articles in 2013, (comprising of about 92,000 light drinkers and 60,000 non-drinkers with cancer) Bagnardi and group (2013) found that light drinking increases the risk of or pharyngeal cancer by 17%; esophageal squamous cell carcinoma by 30%, and breast cancer by 5%. In a more recent review, using data published by the International Agency for Research on Cancer and the World Cancer Research Fund/American Institute for Cancer Research, Islami and group (2018) found that alcohol intake was responsible for an estimated 40.9% of oral cavity/pharynx cancers, 23.2% of larynx cancers, 21.6% of liver cancers, 21% of esophageal cancers, and 12.8% of colorectal cancers. Overall, alcohol intake is responsible for 4.0% of all cancer deaths (Islami et al., 2018).Acetaldehyde, the main metabolite of alcohol is a carcinogen (IARC, 2010;Seitz et al., 2010). It also acts as an irritant to the upper GI tract (WHO, 1988). Its intake is associated with an abnormal production of reactive oxygen and nitrogen species, aberrant DNA methylation, disturbed immune surveillance, and inflammatory response, and elevated estrogen levels in breast cancer cases (Pöschl & Seitz, 2004).
Besides its strong association with several cancers, alcohol abuse can also result in liver and gastrointestinal problems, cognitive defects, peripheral neuropathy, and psychological www.acseusa.org/journal/index.php/aijcs American International Journal of Cancer Studies Vol. 2, No. 1;2020 disorders (Schuckit, 2009). Despite these additional dangers, cancer survivors continue to drink, and this habit is comparable to that found in the general population (Bellizzi et al., 2005).

Diet
Diet plays an important role in cancer (World Cancer Research Fund and American Institute for Cancer Research, 2007;Potter et al., 2016;Bodén et al., 2019). Healthy dietary habits have been associated with lower cancer incidence and mortality (Block, Patterson & Subar, 1992;Thomson et al., 2014;Romaguera et al., 2012) The benefits of a plant-based diet on cancer are well established (Appel et al., 1997). In a review of 206 human epidemiologic studies and 22 animal studies, Steinmetz and Potter (1996) found that greater vegetable and fruit consumption was preventive for cancers of the stomach, esophagus, lung, oral cavity and pharynx, endometrium, pancreas, and colon. Donaldson (2004) (Park et al., 2005) and low dietary fiber may be responsible for 10.3% of colorectal cancer cases (Islami et al., 2018). On the other hand, a diet rich in meat and animal products has been shown to increase cancer incidence, especially cancers of the breast, colon, stomach, and prostate (Bouvard et al., 2015;Chlebowski et al., 2006;Randi et al., 2010;Praud et al., 2013;Mondul, Hollenbeck, & Park, 2013). According to Islami and associates (2018), red meat consumption was associated with 5.4% of all colorectal cancers. Processed meat has a more profound impact on cancer. It has been estimated that eating processed meat such as hot dogs, bacon, sausage, and deli meats, increases the relative risk for colorectal cancerthe risk was 1.16 for each 50 g/day increment in intake (WCRF/AICR, 2018). In another study, Chan et al (2011) calculated that consumption of 50 grams of processed meat per day, increased the risk of colorectal cancer by 18%. In general, processed meat consumption is associated with 8.2% of colorectal cancers (Islami et al., 2018). A proper diet also helps reduce several symptoms associated with cancer such as pain and fatigue (Baguley et al., 2017) and helps improve the quality of life in these individuals (Kassianos et al., 2015). They live longer (Thomson et al., 2014;Kabat et al., 2015). Cancer survivors are at an increased risk of new cancers (Morton et al., 2014;Murphy, Gerber, & Pruitt, 2018).) And a plant-based diet has also been shown to retard the development of these cancers (Kushi et al., 2012). Cancer survivors are also at an increased risk of chronic ailments such as diabetes, osteoporosis, and cardiovascular diseases (Armenian et al., 2017;Underwood et al., 2012). Proper diet will help beneficially modify these risks (Brown, Brauner, & Minnotte, 1993;Zhang et al., 2015). Plant-based diets also reduce obesity, another factor negatively associated with cancer (Schroder, Fito, & Covas., 2007;Wolongevicz et al., 2010;Aljadani et al., 2013).
There are several mechanisms by which a low intake of red meat, processed meat (such as hot dogs, bacon, sausage, etc.), and salt and a high intake of dietary fiber, fruit, and nonstarchy vegetables contribute to the prophylactic and therapeutic effects noted in cancer. These include decreased exposure to carcinogens including N-nitroso compounds, decreased formation www.acseusa.org/journal/index.php/aijcs American International Journal of Cancer Studies Vol. 2, No. 1;2020 of cyto and genotoxic aldehydes, reduced inflammation, enhanced antioxidative capacity, improved DNA repair, reductions in adipose tissue, decreased insulin levels, improved levels of circulating sex and growth hormones  and the reduced formation of heterocyclic aromatic amines and polycyclic aromatic hydrocarbons during high-heat cooking of meat (Sinha et al., 1998).Acrylamide, a chemical produced during high-temperature cooking, a process involved in the production of potato chips, is probably carcinogenic to humans (IARC, 1994).Vegetables diversify gut microbiomes, resulting in lower inflammation, better immunity, decreased tumor genesis, and potentiation of the immunotherapeutic effects in cancer treatment and prevention (Berg et al., 2014).

Sexually transmitted infections
In 2018 Infectious agents modulate lymphocytes directly or impart effects such as immune system depletion or chronic stimulation indirectly, thereby increasing the cancer risk (Engels, 2007).