Lifestyle and Cancer
Lifestyle has a profound effect upon whether someone gets cancer or not. This is demonstrated by the fact that several cancers that are extremely common in the US (colorectal, prostate, and breast cancer) are relatively rare in other parts of the world. Moreover, when people from other parts of the world move to the US, within a generation their cancer rates are close to those of families have lived in the US for generations.
Why is lifestyle, including diet, weight, and exercise, so important? The answer may lie in our genes. Environmental factors, like cigarette smoke, can cause damage to genes. But most cells injure their own DNA accidentally, by producing damaging free radicals as byproducts of normal metabolism. The damage that they cause, however, doesn't necessarily lead to cancer. What can cause tumorous growth are mutations to genes called proto-oncogenes and tumor-suppressor genes.
Oncogenes and Tumor-Suppressor Genes
Every cell contains genes called proto-oncogenes as well as tumor-suppressor genes. Proto-oncogenes are cell growth promoters, and they can be turned into oncogenes by mutations. Oncogenes turn normal cells into cancer cells by releasing an unending stream of growth-stimulating molecular signals, which stimulate cells to reproduce without stopping. Tumor-suppressor genes, on the other hand, stop cell growth. Mutations can cause their growth-stopping signals to be silenced, so that, again, the cell divides endlessly. There are other genes involved in the regulation of cell growth. Some cause cells that are damaged or abnormal to kill themselves. If these genes mutate, damaged cells will continue to reproduce.
The Western Lifestyle
Three factors in the Western lifestyle seem to increase a persons risk for cancer by encouraging mutations to proto-oncogenes and tumor-suppressor genes: diet, overweight, and inactivity. A Western diet is full of mutagens (chemicals that cause cells to mutate), for instance, in red meat cooked at high temperatures. Body fat secretes inflammatory chemicals into the bloodstream that can stimulate the growth of cancer cells. Being active actually lowers the levels of these growth-stimulating chemicals in the blood.
The Good News
There is a positive side to this information: lifestyle is something we can control. By making important changes in our lifestyle, we can hugely reduce our risk of cancer.
1. Don't Use Tobacco
Smoking is the single biggest cause of cancer in the world. All tobacco use causes cancer; it isn't safe to take tobacco as snuff or as chewing tobacco. Besides lung cancer, smoking also causes cancer of the mouth, throat, esophagus, larynx, cervix, bladder, pancreas, kidney, and stomach. It may also promote colon and breast cancer. About 3 million people die of smoking-related causes every year worldwide, and that number will rise to 10 million in the next century if the number of smokers continues to increase.
Even if you don't smoke, you can still be harmed by secondhand smoke, which kills thousands of people every year. Avoid people who smoke and smoke-filled areas.
Lung cancer is now the number-one cancer worldwide. If everyone quit smoking, the number of people who die from cancer would drop by at least one-third, and lung cancer would once again become the rare disease that it once was.
2. Eat a Healthy Diet
There's a great deal of evidence that the typical Western diet, high in red meat and animal fats, and low in fiber, fruits, and vegetables, is a major risk factor for cancer.
3. Maintain a Healthy Weight and Be Active
There's a clear link between obesity and cancer. In fact, one study by the American Cancer Society found that the heaviest people, compared with the leanest, had a significantly increased risk of death from 10 different kinds of cancer in men, and from 12 different kinds in women. Exactly how overweight causes cancer is still unclear. One reason might be that obesity leads to high levels of a growth factor called IGF-1, which is similar to insulin and inhibits cell suicide. IGF-1 might promote the growth of early cancers.
The answer may also lie in the body's inflammatory response. Fat cells release inflammatory chemicals called cytokines into the bloodstream that can stimulate the growth of cancer cells. The more overweight someone is, the greater the level of cytokines, and the greater the chance that precancerous cells will become cancerous.
Exercise has a proven protective effect against cancer. Regular physical activity lowers the levels of both IGF-1 and cytokines in the bloodstream, and it does this even if the person who exercises remains overweight. The lower levels of these cancer promoters are one possible explanation for the protective effect of regular exercise. In addition, estrogen levels in the blood are lowered by regular exercise in women, and this may be why exercise helps protect against getting breast cancer. People should try to be physically active for 30 minutes or more on most days of the week.
4. Protect from the Sun
Skin cancer, or melanoma, is both very common and very preventable. Sun exposure is the most frequent cause, so it pays to protect against the sun:
- Avoid peak radiation hours (10 am-4 pm)
- Stay in the shade
- Cover exposed areas and wear a hat
- Use a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15 - Don't use indoor tanning beds or sunlamps. There's no such thing as a healthy tan.
5. Get Immunized
Certain viruses are associate with specific cancers. Fortunately, there are vaccines available to immunize against these viruses:
- Hepatitis B can increase the risk of developing liver cancer. All babies and some high-risk adults should be vaccinated.
- Human papillomavirus (HPV) is a sexually transmitted virus that can lead to cervical cancer. A protective vaccine is recommended for girls ages 11-12, and for girls and women ages 13-26 who haven't completed the full vaccine series.
6. Avoid High-Risk Behaviors
Viruses associate with certain types of cancer can be transmitted sexually or by sharing contaminated needles, so it's important to use condoms and not share needles.
- HPV is associated with cervical cancer and also cancers of the anus, penis, throat, vulva, and vagina. The more sexual partners a person has in his or her lifetime, the more likely that person is to have HPV.
- Human immunodeficiency virus (HIV), which can lead to AIDS, increases risk of anal cancer, cervical cancer, liver cancer, lymphoma, and Kaposi's sarcoma. People with many sexual partners and intravenous drug users who share needles have an increased risk of HIV.
- Hepatitis B and C increase the risk of liver cancer. Both hepatitis B and hepatitis C can be transmitted through sexual contact with an infected person or sharing needles with an infected drug user.
7. Have Regular Screenings
Regular screening and self-examination for certain types of cancer can increase the chances of discovering cancer early, when the chances of treating it successfully are greatest. Areas of the body that should be screened include the skin, mouth, colon, and rectum. Women should have regular cervix and breast screening. Men should have screening for the prostate and testes.