Many screening tests are available to detect different types of cancer. Typically, screenings aren’t intended to diagnose cancer. If a test comes back abnormal, your doctor will probably need to perform more tests to see if you have cancer. Some screening tests are only performed on people at high risk for developing certain cancers. Researchers are working to determine who benefits most from cancer screening.
Why Is It a Good Idea to Screen for Cancer?
The main goal of cancer screening is early detection. When cancer is found early, it may be easier to treat and cure. Spotting a cancer before it spreads can lower your risk of dying. In general, the more risk factors a person has for cancer, such as family history, age, and others, the more likely it is that he or she will benefit from cancer screening. (1)
What Types of Screening Are Available for Cancer?
Your doctor might perform a physical exam, lab tests, imaging procedures, or genetic tests to screen for cancer. Some common cancer screening tests include:
Mammogram A mammogram is an X-ray of the breast. It’s used to detect breast cancer earlier. Studies show having regular mammograms can lower your risk of dying from breast cancer. (2)Breast MRI This technique uses magnets and radio waves to capture pictures of the breast. It’s typically used with a mammogram on women who are at high risk for breast cancer.Breast Exam During this exam, your doctor performs a physical test to check for lumps on the breast. (2)Pap Test With a Pap test, doctors collect cells and mucus from the cervix and surrounding area. This sample is sent to a lab to be tested for abnormal cells that could turn into cervical cancer. Sometimes, doctors will perform an HPV test along with a Pap to screen for the human papillomavirus (HPV). (2)PSA A PSA blood test is performed to detect prostate cancer in men. It is typically only performed on men at high risk for prostate cancer, and it’s often done along with a rectal exam.Colonoscopy and Sigmoidoscopy These tests use a thin tube with a camera on the end to look inside the colon. A colonoscopy examines the entire colon, while a sigmoidoscopy looks at the left side only. They can detect abnormal growths, called polyps, which can develop into colon cancer. (2)Fecal Occult Blood Test A fecal occult blood test is used to check for blood in the stool, which may indicate you have polyps or colon cancer. (2)CT Scan Low-dose computed tomography, also called a low-dose CT scan, is used to screen for lung cancer. It involves using an X-ray machine to scan the body and provide images of your lungs. (2)CA-125 This blood test may be recommended to detect ovarian cancer in women who are at high risk. It’s often used along with a transvaginal ultrasound. (2)Skin Exam With a skin exam, you or your doctor look for suspicious spots or changes in your skin. They’re often recommended for people who are at risk for skin cancer. (2)Alpha-Fetoprotein This blood test is used to detect liver cancer in people at high risk and is often performed along with an ultrasound. (2)
Can Cancer Be Detected in a Blood Test?
Researchers are working to identify a blood test that could effectively detect different types of cancer. In a 2018 study, investigators analyzed a blood test called CancerSEEK for its ability to screen for eight common cancers. The test looks for protein markers and pieces of DNA in the blood known as circulating tumor DNA. Results showed the test detected cancer with a sensitivity of 69 percent to 98 percent (depending on the cancer type) and a specificity of 99 percent. The most accurate results were found in identifying ovarian and colorectal cancers. The least accurate outcomes were with liver and lung cancers. While the test wasn’t perfect, the researchers believe it was a step in the right direction. They hope to create a single blood test that can detect different types of cancer in the future; for now the test is not available outside of research trials. (3)
Breast Cancer Women ages 40 to 44 can start annual mammograms if they choose to do so. All women with an average risk of breast cancer should begin yearly screenings by age 45. At 55, women can continue yearly mammograms or have them every other year. Regular screening should continue as long as a woman is in good health. Those at high risk for the disease may start earlier screening and might also need a breast MRI, along with standard mammograms. (4)Colon and Rectal Cancer Most men and women should begin colon cancer screening at age 50, but you may need to start earlier if you have certain risk factors. Many different screening tests can be used, so ask your doctor which one is best for your situation. A colonoscopy is typically performed every 10 years for most healthy people. (4)Cervical Cancer Women between ages 21 and 29 should have a Pap test every three years. Those between ages 30 and 65 should have a Pap and HPV test every five years or a Pap only every three years. Women over age 65 who’ve had regular screenings and normal results no longer have to be screened for cervical cancer. You may need to be tested more often or for a longer period of time if you’re at high risk of developing this cancer. (4)Prostate Cancer Starting at age 50, men should talk to their doctors about the pros and cons of screening for prostate cancer. If you’re African American or if your father or brother had prostate cancer, you should have this discussion starting at age 45. (4)Lung Cancer The American Cancer Society doesn’t recommend lung cancer screening for people who are at average risk. But you may benefit from a CT scan if you’re at high risk. “High risk” means you’re 55 to 74 years old, you have a history of smoking 30-pack years or more, and you’re still smoking or have quit in the past 15 years. (4)
People with a high risk of developing other cancers, such as skin cancer, ovarian cancer, or liver cancer, might be given screening tests to detect these diseases earlier. It’s important to talk to your doctor about your family history and other risk factors so you can come up with a screening strategy that fits your needs. RELATED: What Is Lung Cancer?
Not All Cancer Screening Tests Are Foolproof
Although many screening tests have been shown to save lives, there’s debate in the medical community about cancer screening. Not all screening tests are useful, and many can pose risks. For instance, the PSA test is controversial because it sometimes detects prostate cancers that are so slow growing as not to be life threatening, and sometimes prompts over treatment. (5) Some screening tests can produce inaccurate results, such as a “false-positive” or a “false-negative.” A false-positive means your test comes back abnormal even though you don’t have cancer. This can cause unnecessary worry and anxiety. A false-negative result comes back normal when you really have cancer. This can lead to delayed treatment, and sometimes, a worse prognosis. (1) Another potential issue with early screening is that finding the cancer may not improve a person’s health or the chance of a cure. Discuss the benefits and risks of cancer screening with your doctor.
