Did you know that up to 50 percent of all cancers are actually preventable?
Genetics Is Not the Only Risk Factor for Cancer
In addition to genetic factors, lifestyle, and eating habits, cancers are also caused by external carcinogenic factors. For example, ultraviolet rays and ionizing radiation are physical carcinogens; and asbestos pollution in old buildings, alcohol, and aflatoxin in stale peanuts are chemical carcinogens. There are also some bacteria and viruses that can cause cancer, such as Helicobacter pylori—which we can be infected with through food and water consumption, as well as human papillomavirus. These are biological carcinogens.
Cancer gene mutations may be difficult to control, but cancer can be prevented to a large extent if these external carcinogenic factors are effectively controlled, and healthy living and eating habits are followed.
Thirty to 50 percent of cancers in the world can actually be prevented by choosing a healthy lifestyle and staying away from carcinogens. The percentage at which cancer can be prevented by reducing the associated risk factors varies for different cancers. Some cancers can be completely prevented by avoiding exposure to certain external carcinogens; while others are mainly caused by genetic factors, and are less likely to be caused by external carcinogens.
Stay Away From External Cancer Risk Factors—Stay Away From Cancer
Studies in some western countries, such as the United States, Canada, the United Kingdom, and Australia, have relatively consistent conclusions about the impact of external risk factors on cancer induction. An American Cancer Society study of more than 1.57 million U.S. adults over the age of 30 found that 42 percent of cancer cases were attributable to these risk factors. The figure is 33 to 37 percent in Canada, 38 percent in the UK, and 32 percent in Australia.
In China, a developing country, the cancers of 47 percent of male cancer patients and 28 percent of female cancer patients were attributable to these external cancer risk factors. In addition, 34 percent of new cancer cases in men and 35 percent of new cancer cases in women in Brazil, also a developing country, were attributable to external cancer risk factors.
Deaths from cancer can be attributed to the effects of related factors, which in descending order are: smoking, being overweight, alcohol use, radiation, physical inactivity, bacterial and viral infections, and poor eating habits – such as low intake of fruits and vegetables and dietary fiber, consumption of processed meats and red meat, as well as low dietary calcium intake. According to the latest research published in The Lancet in 2022, 44.4 percent of cancer deaths worldwide are related to various risk factors.
In addition, women’s use of menopausal hormonal therapy and the combined oral contraceptive pill, as well as insufficient breastfeeding time, can increase the risk of cancer of the reproductive organs.
Moreover, exposure to some toxic chemicals can also cause cancer. For instance, exposure to asbestos can cause lung cancer; and drinking water that contains high levels of arsenic can cause skin cancer, bladder cancer, and lung cancer.
Everyone hears that smoking causes cancer, but you may not know that it is actually the number one risk factor for cancer. One out of every three cancer deaths is attributable to smoking. Smoking can cause cancer in almost every part of the body, from the mouth to the bladder.
Harmful chemicals in the smoke that enter the lungs and spread throughout the body through the blood and lymphatic system will interfere with normal cell growth and damage cells’ DNA, making it harder for the cells to repair their DNA damage. The chemicals also damage genes that protect the body from cancer. Over time, the accumulation of DNA damage in cells will lead to cancer.
A study of more than 220,000 people showed that smoking increased an individual’s risk of various types of cancer by 42 percent compared with non-smokers. Specifically, the risk of lung cancer, laryngeal cancer, liver cancer, esophageal cancer, and bladder cancer among smokers was 17.7 times, 11.3 times, 4.1 times, 3.8 times, and 3.1 times that of non-smokers, respectively… About half of smokers will develop cancer by the time they are 80 years old, and 14 percent will develop lung cancer.
Being overweight is the second-leading preventable cause of cancer after smoking, and 7.8 percent of new cancer cases in the United States are due to patients being overweight. However, people are becoming more tolerant of their own weight gain, with one-third of overweight Americans not even being aware that they are overweight.
Having excess weight causes up to 13 types of cancer, such as postmenopausal breast cancer, endometrial cancer, colorectal cancer, pancreatic cancer, and gallbladder cancer, among others. Postmenopausal breast cancer is the most common obesity-related cancer in women, and colorectal cancer is the most common obesity-related cancer in men.
Being overweight can lead to changes in the body, including long-term inflammation and higher-than-normal levels of insulin, insulin-like growth factors, and sex hormones, and this ultimately causes cancer. The more weight a person gains and the longer they stay overweight, the higher their risk of developing cancer.
Alcohol use ranks after smoking and being overweight. Alcohol-related cancers account for 5.6 percent of new cancer cases in the United States. A Lancet study proves that there is no safe minimum consumption of alcohol for the human body, and it is best not to drink it at all.
Drinking alcohol will increase the risk of developing oropharyngeal cancer, esophageal cancer, stomach cancer, breast cancer, liver cancer, and colorectal cancer.
The decomposition of ethanol in alcoholic beverages in the body is divided into two steps: it is first decomposed into acetaldehyde, and then into acetic acid. Acetaldehyde is a toxic chemical that damages DNA and proteins in cells, which can lead to cancer. In addition, alcohol can impair the body’s ability to break down and absorb various nutrients, such as vitamin A, folic acid, vitamin C, vitamin D, vitamin E, and carotenoids; and deficiencies in these nutrients can increase the risk of cancer. At the same time, alcohol will also increase the level of estrogen in the blood, leading to an increased risk of breast cancer.
Alcoholic beverages may also be contaminated with carcinogenic pollutants such as nitrosamines, asbestos fibers, phenols, and hydrocarbons during their fermentation and production.
Radiation can penetrate our bodies, and the energy it emits can change the molecules within the cells of our body. The DNA of cells is attacked and damaged, which eventually causes cancer. There are two main types of radiation that cause cancer:
- Ultraviolet radiation, especially from the sun, can cause all major types of skin cancer, such as melanoma. In addition, ultraviolet radiation from tanning beds has also been linked to skin cancer and ocular melanoma. Melanoma caused by ultraviolet radiation accounts for 4.7 percent of all cancer cases in the United States.
- Ionizing radiation from X-rays, CT scans, fluoroscopy, and nuclear medicine scans can cause many types of cancer, including leukemia, thyroid cancer, breast cancer, myeloma, and others.
The increasing use of CT scans for medical diagnosis in recent years has increased patient exposure to ionizing radiation. It is estimated that unnecessary repeat CT scans account for one-third of all CT scans in the United States. In addition, two researchers from Columbia University Irving Medical Center recently published an article in The British Journal of Radiology, questioning doctors’ increasing use of CT scans as a screening procedure for asymptomatic patients.
Columbia University’s Center for Radiological Research once conducted a study in 2001, stating that there were 600,000 abdominal and head CT examinations performed on children under the age of 15 in the United States every year. At the time, researchers calculated that this could result in 500 eventual deaths from cancers caused by CT radiation.
In addition to medical examinations, a medical application of radiation is radiation therapy for cancer. Although radiation therapy can kill cancer cells or slow down their growth, it also has some negative effects, including possible risks to normal tissue surrounding a tumor. According to a study published in the British Journal of Cancer, exposure of the heart to ionizing radiation during radiation therapy for breast cancer increases the risk of ischemic heart disease. Other studies have shown that patients who receive radiation therapy for breast cancer have a progressively increased risk of heart disease and lung cancer. The Mayo Clinic’s information on radiation therapy mentions that radiation therapy can, in rare cases, cause other cancers many years later.
Cancers related to the lack of physical activity account for 2.9 percent of new cancer cases in the United States.
Physical inactivity can lead to hormonal imbalances and insulin resistance, which increases inflammation in the body, thereby increasing the risk of cancer. Inactivity can also lead to weight gain.
Fourteen percent of colon cancer cases and 11 percent of postmenopausal breast cancer cases were attributable to inactivity; other cancers linked to inactivity include prostate, uterine, and lung cancers. Those who are sedentary face a 24 percent higher risk of colorectal cancer, a 32 percent higher risk of endometrial cancer, and a 21 percent higher risk of lung cancer.
Conversely, physical activity can regulate hormones such as insulin-like growth factors and estrogen, and affect how quickly food moves through the gut, thereby lowering the body’s exposure to any potential carcinogens.
There are also some cancer cases in the United States that are simply caused by infections. Many cancers can be prevented if measures are taken against these viral and bacterial infections.
The following types of bacteria or viruses can cause cancer:
Human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HPC), Helicobacter pylori, human immunodeficiency virus (HIV), human herpesvirus 8 (HHV8), and Epstein–Barr virus.
- HPV can cause cervical, penile, vaginal, anal, oropharyngeal, and vulvar cancers.
Most people infected with HPV do not know that they have an infection. Normally, the body’s immune system will clear the HPV infection naturally within two years. According to statistics, by the age of 50, at least 4 out of 5 women will have been infected with HPV at some point in their lives. HPV infection is also common in men, and it is often asymptomatic. When the body’s immune system cannot rid itself of cancer-associated HPV infection, normal cells can turn abnormal and eventually develop into cancer. About 10 percent of women with cervical HPV develop long-term infections, which increases the risk of cervical cancer.
The Centers for Disease Control and Prevention (CDC)’s Advisory Committee on Immunization Practices (ACIP) recommends HPV vaccination to prevent new HPV infections and associated cancers and other diseases. The HPV vaccine, given at ages 9 to 12, provides the greatest protection. Adults aged 27 to 45 would benefit less from getting vaccinated as they are more likely to have been exposed to HPV. Hence, routine vaccination is not recommended for people in this age group.
- The hepatitis B virus can cause liver cancer, and the hepatitis C virus can cause liver cancer and non-Hodgkin’s lymphoma.
- Helicobacter pylori can cause stomach cancer.
- Human immunodeficiency virus, also known as HIV, can cause anal cancer, Kaposi’s sarcoma, cervical cancer, Hodgkin’s lymphoma, and non-Hodgkin’s lymphoma
- Human herpesvirus 8, also known as Kaposi’s sarcoma herpesvirus, can cause Kaposi’s sarcoma.
- Epstein–Barr virus can cause Burkitt lymphoma, nasopharyngeal carcinoma, and Hodgkin’s lymphoma.
An Improper Diet
A diet high in fat, protein, calories, and red meat increases the risk of colorectal cancer. Eating processed meat also increases the risk of stomach cancer in addition to an increased risk of colorectal cancer. Cancers caused by the consumption of red and processed meat account for 1.3 percent of new cancer cases in the United States.
Low dietary fiber intake also increases the risk of colorectal cancer. Furthermore, a low intake of fruits and non-starchy vegetables increases the risk of oropharyngeal and laryngeal cancers. In addition, insufficient fruit intake also increases the risk of lung cancer. These cancers, caused by a low dietary fiber intake and low fruit and vegetable intake, account for 2.8 percent of new cancer cases in the United States.
What Cancers Are Preventable?
A study, published in CA: A Cancer Journal for Clinicians, further compared the population-attributable fractions (PAF), that is, the percentages that can be attributed to external risk factors, across different cancers.
Specifically, the PAF of cervical cancer and Kaposi’s sarcoma incidence was 100 percent. In other words, both of these cancers are potentially preventable if preventive measures are in place.
Melanoma skin cancer, which is mainly affected by the sun’s ultraviolet radiation, followed closely with a PAF of 95.1 percent.
The PAF of lung cancer was 85.8 percent.
The PAFs of other cancers were as follows:
Lastly, among the cancers studied, the only ones with a PAF below 10 percent were lymphoma and ovarian cancer.
Flora Zhao is a health reporter for The Epoch Times. Have a tip? Email her at: [email protected]
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