Why We Screen for Some Cancers and Not Others

Screening means having a test that looks for cancer or another disease in people who don’t have any symptoms. Some screening tests can find growths and remove them before they have a chance to turn into cancer. Other screening tests can find cancer early when it’s easier to treat.

The benefits of screening tests – finding cancer early or sometimes even preventing it by removing growths before they have a chance to turn into cancer – must be weighed against any risks of the tests themselves. Risks may include anxiety, pain, bleeding, or other side effects. And screening isn’t perfect. Sometimes screening misses cancer. And sometimes it finds something suspicious that turns out to be harmless (called a false-positive), but still needs to be checked out through additional tests that also carry risks and cause more stress.

This is why the American Cancer Society uses a formal process to review scientific evidence to create guidelines for cancer screening. The guidelines advise people about what screening tests they should get, when they should get them, and how frequently the tests should be done. The higher a person’s risk for cancer – due to age, family history, or other factors – the more likely the benefits of screening will outweigh the risks.

American Cancer Society Screening Guidelines

The Society’s guidelines for average-risk adults recommend regular screening for breast cancer, cervical cancer, and colorectal cancer, based on scientific evidence that shows those screenings save lives. Weighing the benefits and risks of screening for prostate cancer and lung cancer is more complicated because other individual factors are involved. Therefore, the American Cancer Society recommends people become informed and talk with their doctor regularly to make the screening decisions that are best for them. For many other cancer types, researchers continue to conduct studies to learn the best ways to find cancer before symptoms appear.

• Breast Cancer: Women should be able to start screening at age 40 if they want to. All women at average risk of breast cancer should begin yearly screening by age 45. At age 55, women can choose to continue with yearly mammograms, or choose to have them every other year. Women should talk to their doctor about their own personal risk for breast cancer and about any breast changes they notice. Regular mammograms should continue for as long as a woman is in good health.
• Cervical Cancer: Women between the ages of 21 and 29 should have a Pap test every 3 years. Women between the ages of 30 and 65 should have both a Pap test and an HPV test every 5 years, or a Pap test alone every 3 years. Women over age 65 who have had regular screening tests with normal results should no longer be screened for cervical cancer. Women who are at high risk for cervical cancer may need to be screened more often. Talk to your doctor about the screening schedule that is best for you.
• Colorectal Cancer: Adults at average risk should begin regular colorectal screening at age 45, but those with a family history or other risk factors should talk with their doctor about beginning earlier. Several different tests can be used to screen for colorectal cancer, including colonoscopy, flexible sigmoidoscopy, guaiac-based fecal occult blood test, and more. Discuss which test is right for you with your doctor, and talk to your insurer about coverage. All abnormal results on non-colonoscopy screening tests should be followed up with a colonoscopy.
• Lung Cancer: People at high risk for lung cancer may benefit from low-dose CT scan (LDCT). “High risk” refers to current smokers (or those who have quit within the past 15 years) 55 to 74 years old who have a smoking history of 30 pack-years or greater. This means smoking an average of 1 pack a day for 30 years, 2 packs a day for 15 years, or the equivalent. Talk to your doctor about your risk, and the benefits, limits, and harms of screening with LDCT.
• Prostate Cancer: Men should discuss the possible risks and benefits of prostate cancer screening with their doctor before deciding whether to be screened. The discussion should take place starting at age 50 for men who are at average risk of prostate cancer and expect to live at least 10 more years. It should take place at age 45 for men who are at higher risk, including African American men and men who have a father or brother diagnosed with prostate cancer, and at age 40 for men at even higher risk. Talk to your doctor about your history, and what screening schedule is best for you.