~ Part I ~
Knowing how to prevent cancer (along with early detection and treatment) is important because it really can save lives and reduce suffering from cancer. Cancer causes one in every seven deaths, worldwide. It is more than HIV and AIDS, tuberculosis, and malaria combined. Fortunately, about half of cancer cases can be prevented by the current evidence based guidelines.There are three type of cancer prevention: primary, secondary, and tertiary prevention.
* Primary prevention refers to avoiding or eliminating cancer causing substances. The goal is to prevent the cancer before it begins in the first place. Example: avoid smoking, vaccination against cancer causing viruses, and elimination of carcinogens in the workplace. Primary prevention is only possible when the cause of cancer is known.
* Secondary prevention refers to early detection and screening. The goal is to detect premalignant cells before they become cancerous or early stage cancer. Example: PAP smears test for cervical cancer, mammography for breast cancer, or colonoscopy for colorectal cancer.
* Tertiary prevention refers to the treatment of cancer patients. The goal is to prevent premature death and to maintain quality of life.
The burden of cancer is great, but it can be prevented. Effort to reduce the burden of cancer happens on two levels: personal level, and national and community levels. In the personal level, we as an individual can try to do things that lower our risk of developing certain cancers.
Here are several factors we should know to reduce our risk:
1. Tobacco and cancer
It is clear that tobacco is the world’s leading cause of cancer and cancer related deaths. Cigarettes are designed to deliver nicotine, powerful drugs that stimulate pleasure sensors in the brain. It increases mood in a positive way, it eases anxiety and makes people feel less depressed. However, these positive affects are offset significantly by all the harm in tobacco. When people smoke, they take in more than just nicotine. That smoke is a mix of thousands of compounds, including more than 70 chemicals that are known as possible human carcinogens. Smoking increases a risk of a lung cancer on average 5-10 fold (many recent studies show as much as 20 fold or higher). Men who smoke have a 27 times higher rate of oral carcinoma than nonsmokers. In addition, smoking raises a person’s risk of other cancers. As those carcinogens get to the lungs, they go into the bloodstream and carried throughout the body. Thus, smoking also causes the cancer of larynx, the voice box, the oral cavity, the esophagus, the stomach, the pancreas, the bladder, the kidney, the liver, the cervix, also colorectal cancer and some leukemias.
Quitting tobacco at any age is a big benefit. Even if you are a cancer patient or you have some other terminal illness.
2. Alcohol and cancer
Based on many research studies, there is a strong link between alcohol drinking and several types of cancer. People who drink about two drinks or more per day, have at least two or three times greates risk of developing head and neck cancer, especially the lips, oral cavity, throat, larynk, compare to the nondrinkers. Moreover, the risk of these cancers is still greater among those who consume alcohol and also use tobacco. They work together to cause you more harm because alcohol itself incrases the absorption of tobacco carcinogens by the body. People who inherit a deficiency in an enzyme that metabolizes alcohol, also have a higher risk of alcohol-related esophageal squamous cell carcinoma. Alcohol consumption is also a cause of liver cancer, correlate with a modest increase in colorectal cancer, and is a clearly established cause of breast cancer in women. One study in United Kingdom, called the Million women’s study found that a drink per day produces about a 12% risk for breast cancer, which means for each drink you have an additional 12% chance of getting breast cancer. There is some evidence suggesting that some alcoholic beverages also reduce the risk of heart disease, try to balance that possible protected effect of alcohol against the increased risk of cancers. If you drink, drink in moderation and be aware of your risks.
3. Diet and cancer
Although each individual may have unique health issues regarding diet and nutritions, some recommendatios are made by the Public health guidelines (meaning that recommendations regarding diet and nutrition are appropriate for entire populations). It is clear that one of the keys to orchestrating the anti-cancer diet is the principle of focusing upon a plant-based diet. Consume a diverse array of fruits, vegetables, and legumes along with whole grains each day should be your basic foundation. Diet rich in lipids, particularly saturated fats are often associated with the risk of several cancers and may promote cardiovascular diseases. Saturated fats typically come from animal foods (briefly: meats). Studies do suggest that populations consuming large amount of red meats experience cancers such as breast, prostate, and colon cancers. Also, excessive salt intake may have health risks for hypertension and cardiovascular diseases, as well as some cancers. One of the most common questions regards what dietary supplements to consume to prevent cancer. The well-done studies on dietary supplements and cancer risks have does far been unimpressive. At the present time, a multivitamin and mineral supplement that meets the RDA (Recommended Dietary Allowance) will likely post little health risk, but potential benefits for cancer reduction still have not been established.
4. Heredity and cancers
Cancer is a genetic disease, but not all cancers are hereditary. Genetic disease means that cancer is a disease of the genes, caused by changes (known as mutations) that occur in the genes of the body during human’s lifetime. Hereditary cancer refers to gene mutations that are passed from one generation to another, increasing an individual’s risk of developing particular kinds of cancer. The individual does not inherit a cancer, but they inherit a gene mutation that increases the risk that they will develop a certain kind of cancer sometime during his or her life. There are four red flags that signal the possibility that a cancer-related gene mutation might run in the family.
* First, if the cancers are diagnosed at an early age, usually younger than 50 years old.
* Second, there are multiple cases of cancers on the same side of the family
* Third, if an individual has developed multiple cancers themselves, or cancers on both sides of their body, for example bilateral breast cancer.
* Fourth, if the cancers are rare. When individuals develop rare tumors, it is more likely that they might be hereditary.
The family members most at risk of carrying cancer-related gene are first and second degree-relatives. First degree relatives are those who share half of your genes (mother, father, sister, borther, and children). Second degree relatives are those who share a quarter of your gene (half siblings, aunts, uncles, nieces, nephews, grandparents, and grandchildren).
The risk of developing breast cancer and ovarian cancer in women is much greater for both men and women who inherit a harmful mutation in one or both of genes called BRCA1 and BRCA2. These mutations can be inherited from either your mother or father. In the general population, only 1.4% of women will develop ovarian cancer during their lifetime; however, women with BRCA1 or BRCA2 mutations, the risk is significantly increased between 11 to 39%. Also they have 65% lifetime risk for breast cancer, significantly higher than 12% lifetime risk in the general public. Men with BRCA2 mutations also have a higher risk of breast and prostate cancer. Another example of an inherited gene mutations that led to cancer is Lynch syndrome. A person is said to have Lynch syndrome if they have a mutation in one of four genes called MLH1, MSH2, MSH6, or PMS2. If they have this mutation, they are in 100% lifetime risk of cancers. They are prone for developing colorectal cancer, followed by uterine, ovarian, and gastric cancer. All are usually diagnosed before age 50. People with Lynch syndrome need close cancer surveillance and do annual colonoscopy starting at age 25.
It is important to identify people who carry cancer-related gene mutations because it allows family members to seek counseling and testing. Genetic counseling can help explain the meaning of the findings and what cancer prevention options are recommended. This will allow all family members to undergo predictive testing, so those of the highest risk of cancer can benefit from intensive cancer surveillance and prevention options. Ultimately, this can save lives.
Summary from the lecture “Introduction to the Science of Cancer” – The Ohio State University Comprehensive Cancer Center-James
Kathryn - Tokyo