
Learn about the basics of cancer, from how it develops to how to prevent it, in this helpful guide.
For more than a century, the American Cancer Society has provided hope and answers for people facing a cancer diagnosis. Now we need help to continue the research for treatment and cures, the 24/7 support for cancer patients, the rides to appointments and Hope Lodge accommodations, and cancer screenings.
Under the best of circumstances, a cancer diagnosis can be frightening and devastating. Now, as the COVID-19 pandemic continues to affect our lives, cancer patients – many who already have compromised immune systems – are more vulnerable than ever. The American Cancer Society has never faced a threat to our mission like COVID-19. The way we fuel our fight has changed drastically this year, but we can’t leave cancer patients to fight this alone. There’s never been a more critical time for those with cancer and their families, so we at the American Cancer Society are doing everything we can to continue our fight for a world without cancer.
Causes of Cancer
There are many different causes of cancer. Some we can control, and others we cannot. Some of the most common causes of cancer that we can control are smoking and tobacco use, body weight, diet and physical activity, and exposure to the sun. Research has shown that at least 18 percent of all cancers diagnosed in the United States are related to these causes, and therefore are likely preventable.
There is no safe form of tobacco use. Nearly half of all Americans who keep smoking will die of the disease. Every year, smoking causes 1 out of every 5 deaths in the U.S. Smoking causes about 30 percent of all cancer deaths, and approximately 80 percent of all deaths from lung cancer. Lung cancer is the leading cause of death in both men and women, and one of the most difficult cancers to treat. In addition to causing lung cancer, smoking and tobacco use are risk factors for 12 other types of cancer. The American Cancer Society was the first to link smoking to cancer and continues to advocate for smokers to quit. Each year, the American Cancer Society hosts the Great American Smokeout on the third Thursday of November as an opportunity for people who smoke to commit to a healthy, smoke-free life. In the more than 40 years since this event was first held, millions have ended their dependency on tobacco for good. This year, the Great American Smokeout will take place on Thursday, November 19.
Getting to and staying at a healthy weight is important to reduce the risk of cancer and other chronic diseases, such as heart disease and diabetes. Being active can help reduce your cancer risk by helping with weight control. The latest recommendations for adults call for 150-300 minutes of moderate intensity or 75-150 minutes of vigorous intensity activity each week, or a combination of these. Getting to or exceeding the upper limit of 300 minutes is ideal. It’s also important to limit sedentary behavior such as sitting, lying down, watching TV, or looking at your phone or computer.
Alcohol increases the risk for several types of cancer. The more alcohol you drink, the higher your cancer risk. But for some types of cancer, most notably breast cancer, consuming even small amounts of alcohol can increase risk. People who choose to drink alcohol should limit their intake to no more than two drinks per day for men and one drink per day for women. The recommended limit is lower for women because of their smaller body size and slower breakdown of alcohol. One drink of alcohol is defined as 12 ounces of beer, 5 ounces of wine, or 1½ ounces of 80-proof distilled spirits (hard liquor). In terms of cancer risk, it is the amount of alcohol, not the type of alcoholic drink, that is important.

Eating well is an important part of improving your health and reducing your cancer risk. Healthy eating includes foods that are high in vitamins, minerals, and other nutrients, including vegetables, fruits, whole grains, and fiber-rich beans and peas. You should avoid red and processed meats, highly processed foods, and sugar-sweetened beverages like soft drinks.
Cancer has also been linked to exposure to the sun and ultraviolet (UV) radiation. The amount of UV exposure a person gets depends on the strength of the rays, the length of time the skin is exposed, and whether the skin is protected with clothing or sunscreen. Make sure you practice “Slip! Slop! Slap! And Wrap!” when outside: Slip on a shirt, Slop on a broad-spectrum sunscreen of at least 30 SPF, Slap on a hat (wide-brimmed is best), and Wrap on sunglasses before any sun exposure to reduce your cancer risk.
Early Detection Saves Lives
The goal of screening is to detect cancer when it is at its earliest stages, before it has spread, which is when it is the most treatable. Screening increases the chances of detecting certain cancers early, when they are most likely to be curable.

The COVID-19 pandemic has resulted in many elective procedures being put on hold, and this has led to a substantial decline in cancer screening. Decisions about restarting screening depend on many factors, and they may not be the same for every person. Some important things to consider include your risk of getting a certain type of cancer, how long it’s been since you were last screened for it, how common COVID-19 is in your community, and your age and overall health.
If you had an appointment for screening that was postponed or canceled, talk to your health care team about when to reschedule. Your provider can discuss balancing the risks and benefits of being screened now or postponing for a later date after considering your personal and family history, other risk factors (weight, smoking, etc.), and the timing of your last screening.
Remember that cancer screening can save lives, so it’s important that you don’t forget about it. Getting back on track with cancer screening at some point should be a priority.
Breast Cancer
After skin cancer, breast cancer is the most commonly diagnosed cancer in women. It is the second leading cause of cancer death after lung cancer. Breast cancer is often found after symptoms appear, but many women who are diagnosed with the disease have no symptoms.
• Women ages 40 to 44 should have the choice to start annual breast cancer screening with mammograms (X-rays of the breast) if they wish to do so.
• Women ages 45 to 54 should get mammograms every year.
• Women 55 and older should switch to mammograms every two years, or can continue yearly screening.
• Screening should continue as long as a woman is in good health and is expected to live 10 or more years longer.


• All women should be familiar with the known benefits, limitations, and potential harms linked to breast cancer screening.
Women should also know how their breasts normally look and feel and report any breast changes to a health care provider right away.
Colon and Rectal Cancer and Polyps
For people at average risk for colorectal cancer, the American Cancer Society recommends starting regular screening at age 45. This can be done either with a test that looks for signs of cancer in a person’s stool (a stool-based test), or with an exam that looks at the colon and rectum (a visual exam). Talk to your health care provider about which tests might be good options for you. No matter which test you choose, the most important thing is to get screened. If you choose to be screened with a test other than colonoscopy, any abnormal test result needs to be followed up with a colonoscopy. If you’re in good health, you should continue regular screening through age 75.
Cervical Cancer
• Cervical cancer screening should start at age 25. People younger than 25 should not be tested because cervical cancer is rare in this age group.
• People between the ages of 25 and 65 should get a primary HPV (human papillomavirus) test done every five years.

• People over age 65 who have had regular cervical cancer testing in the past 10 years with normal results should not be tested for cervical cancer. Once testing is stopped, it should not be started again. Those with a history of a serious cervical pre-cancer should continue to be tested for at least 25 years after that diagnosis, even if testing goes past age 65.• Screening should continue as long as a woman is in good health and is expected to live 10 or more years longer.
• People whose cervix has been removed by surgery for reasons not related to cervical cancer or serious pre-cancer should not be tested.
• People who have been vaccinated against HPV should still follow the screening recommendations for their age groups.
Because of their health history, some individuals may need a different screening schedule for cervical cancer. Talk to a health care provider about your history.

Lung Cancer
The American Cancer Society recommends yearly lung cancer screening for certain people at higher risk for lung cancer who meet the following conditions:
1. Are ages 55 to 74 years and in fairly good health
and
2. Currently smoke or have quit smoking in the past 15 years
and
3. Have at least a 30 pack-year smoking history. (A pack-year is one pack of cigarettes per day per year. One pack per day for 30 years or two packs per day for 15 years would both be 30 pack-years.)
You should also talk with your insurance provider about your coverage. The most important thing to remember is to get screened regularly, no matter which test you get.
Before getting screened, you should talk to your health care provider about:
• Your risk for certain cancers
• The possible benefits and harms of cancer screening
• Where you can get screened
Every three minutes a person is diagnosed with cancer, and every person with cancer is more vulnerable during this pandemic. This is the most critical time for cancer patients and our lifesaving mission. For more cancer information, answers, support, to donate, or to become a volunteer, please visit cancer.org/AZ, or call our National Cancer Information Center 24/7, 365 days a year at 1-800-227-2345. To help those most in need, please consider a donation cancer.org/donatelocal.
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