Cancer Doesn’t ‘Just’ Happen: Less than 10% of all cancers are hereditary
Pago Pago, AMERICAN SAMOA — In 2008 it was estimated that by 2020 the world population would reach 7.5 billion. As of November 11, 2018, the actual number is 7.2 to 7.7 billion with the majority living in the poorest countries with the highest smoking rates and exposure to environmental pollutants. Approximately 15 million new cancer cases were expected to be confirmed, and 12 million patients were expected to die of cancer in 2008. In 2018, 17 million cases have been confirmed, and 9.6 million have died worldwide – more cancer, less deaths. 33% of cases are linked to tobacco use and exposure to secondhand smoke; and 1 in 4 Americans could expect a cancer diagnosis at some point in their lives (Parsa, 2012).
While the exact cause of most cancers is unknown, according to research studies, less than 10% of all cancer cases are attributed to genetic defect or heredity (Parsa, 2012; NIH, 2018). Cancer is a complex disease resulting from environmental exposures that drive tumor development and growth. Up to 95% of cancers are primarily rooted in environment and lifestyle.
Cancer is a disease of cells, which contain multiple defects (NIH, 2018). Many environmental (external) factors combine with internal changes to cells leading to human cancers. Environmental factors disrupt the normal cellular growth and networking that make our bodies work. These genetic ‘mutations’ or changes in four groups of genes play a role in altering these cells: Oncogenes, Tumor Suppressor genes, Apoptosis genes, and DNA repairing genes. A gene is a stretch of DNA or RNA that determines a certain trait. These genes can protect cells against cancer, ‘suppress’ cancer growth, and repair cells. Or, in the case of cancer, the cells are changed in a way that invades the body and kills healthy cells and tissue.
Inflammation is the link between factors that cause cancer and factors that prevent cancer. Inflammation is an immune system response to injury and infection, triggering the process of healing and repairing cells and tissue, as wells as defending the body against viruses and bacteria to prevent disease. If healing doesn’t happen or the immune system isn’t strong enough to overcome the infection, disease grows and spreads. Chronic or long-term inflammation is related to heart disease, strokes, cancer. In most cancer cases, chronic inflammation is present before ‘tumorigenesis’ which is the production of cancerous (or benign/non-cancerous) tumors. Meaning, the presence of long-term inflammation can be an indicator of cancer risk (Anand, P. 2008).
Most carcinogens or cancer-causing agents have been shown to activate chronic inflammation and most tumors are regulated by it (NIH, 2018). In fact, all lifestyle factors that cause cancer and all agents that prevent cancer are linked through chronic inflammation. Many factors influence whether a person exposed to a carcinogen will develop cancer, including the amount and duration of the exposure, and the person’s physical ability to fight the inflammation that will feed tumor growth (NCI, 2015). In most populations, environmental exposure to carcinogens is responsible for less than 19% of all cancers. It is the exposure to lifestyle-based carcinogens, which have the greatest health impact.
Carcinogenic lifestyle factors include cigarette smoking, unhealthy diet, alcohol use, over-exposure to sun, environmental pollutants, infections, stress, obesity and physical inactivity. Of all cancer-related deaths, 25-30% are due to tobacco; 35% are linked to unhealthy diets; 15-20% are due to infections. The remaining are due to other factors like exposure to radiation, food additives, side effects of prescription drugs and medications and any combination of factors. Cancer is a preventable disease in 90% of the cases but requires major lifestyle changes (Anand, 2008).
The effects of aging (most cancers are diagnosed at age 55+) and genetic-cellular weakening combine to damage cells, causing them to divide and lead to cancer. Environmental factors like smoking, stress and obesity fast-track this process.
180,000 Americans die every year of cancer caused by smoking: 85% of all lung cancers, and 30% of all deaths. Breathing in secondhand smoke increases cancer risk by 5% (Parsa, 2012). There are 4000 chemicals in tobacco smoke – 400 are harmful to human health. Tobacco use increases the risk of developing at least 14 types of cancer including kidney, bladder, throat, stomach, mouth, cervix, and pancreas. Tobacco contains 50 known carcinogens – things that directly affect cells and tissues to literally CAUSE CANCER. No single commonly available agent in the world is known to have more impact on cancer growth than tobacco.
Avoidance of tobacco smoking and breathing secondhand tobacco smoke has been shown to reduce cancer incidence – the number of cancer cases – each year. In fact, the protection against such carcinogenic exposure should be the number one priority or goal of cancer prevention programs (Parsa, 2012). Prevention is defined as the reduction of cancer death by reduction in cancer diagnosis by avoiding carcinogenic exposure, improving lifestyle, and early detection of cancer lesions/tumors (NCI, 2018).
The National Toxicology Program (NTP) of the U.S. Dept. of Health plus the International Agency for Research on Cancer (IARC) under the World Health Organization systematically test environmental agents for cancer causing properties. The NTP has identified 56 carcinogens as of 2014, and the IARC maintains a stratified list of 400 (Cancer, 2015). Additionally, outdoor and indoor air pollution, food additives, and long-term exposure to chlorinated drinking water have been associated with increased risk of cancer (Arnand, 2008).
Other agents include alcohol, responsible for 3.6% of all human cancers and classified by the IARC as a group-1 carcinogen. The risk is higher for drinkers who also smoke. Viruses and infections cause 18% of all cancers, including heliobacter pylori, Strep bovis, HPV and Epstein-Barr. But by far, besides tobacco use, obesity and physical inactivity (lifestyle factors) have the most impact in laying the foundation for cancer growth. Besides creating mass inflammation throughout the body leading to cellular breakdown, according to the American Cancer Society, in the U.S., 14% of men and 20% of women can attribute their cancer to excess weight or obesity. A reduction of almost 50% in the incidence of colon cancer was observed among those with the highest level of physical activity in one study (Arnand, 2012; Calle, 2003).
People are constantly asking, ‘how can I prevent cancer?’ The answer has been the same for over 25 years and continues to be the most effective:
1 – avoid exposure to carcinogens i.e. secondhand smoke, air and water pollutants, chemicals and gases
2 – be physically active every day
3 – eat a healthy diet full of fruits, vegetables, grains
4 – don’t smoke and limit alcohol intake
5 – complete the recommended cancer screening for your age
What you do, and not what your ancestors did, impacts your risk of developing cancer. Even if cancer ‘runs in my family’, it only increases your risk – it is not a death sentence. Take responsibility for your health today.