Why is cancer screening important?

The goal of cancer screening is to find cancer earlier or detect precancerous changes before they develop into cancer. Some cancers do not cause noticeable symptoms in their early stages, which means screening can sometimes find changes before you feel unwell.

Common types of cancer screening tests

Cancer screening is not one-size-fits-all. Recommendations vary based on age, personal and family medical history, as well as individual risk factors. Some screenings can be done at home or during a routine doctor’s visit, while others are done in a clinic or imaging center and may require a referral.

It also helps to know the limits of screening before finding out more about specific tests. Like any medical test, screening can come with limitations. A false positive means a result looks abnormal even though nothing serious is found, which can lead to extra testing. A false negative can happen when a result looks normal even though cancer is present, which is one reason healthcare providers may still recommend repeat screening over time, and why new symptoms should be discussed even after a normal test.

Below is a high-level look at common screening tests, including what they are designed to do and what they are designed to detect.

Breast cancer screening: Mammograms

Mammograms are imaging tests (X-rays) that look for changes in breast tissue that may not be noticeable during a physical exam. They are commonly used to screen for breast cancer in women at certain ages, based on clinical guidance and individual risk.

For women at average risk, the American Cancer Society recommends to start getting mammograms at age 45, with the option to continue annual screenings or shift to every two years at 55. Women ages 40 to 44 have the option to start screening early if they’d like. Speaking with a healthcare provider can help determine when you should begin regular screenings.

Mammograms are typically done through a healthcare provider or imaging center and may require a referral, depending on your location and insurance.

Colorectal (colon) cancer screening: Colonoscopy and stool tests

Colorectal cancer screenings look for cancer or precancerous growths in the colon or rectum (the last part of the large intestine). There are different screening options, including:

• At-home stool-based tests, which look for signs of blood or other indicators
• Colonoscopy, a procedure that allows doctors to directly examine the colon and rectum

Guidelines typically recommend screening using one of these methods. The choice depends on individual factors and should be discussed with a healthcare provider.

For adults at average risk, the American Cancer Society recommends they start regular screening at age 45 and continue through age 75. Adults who are 75-85 years old should talk with their doctor to make a shared decision on continuing screenings. Those 85 years and older do not need to get screened.

At-home stool tests do not usually require a referral, while colonoscopies are typically done through a specialist and may require one.

Learn more about What to ask your doctor about colorectal cancer screening.

Cervical cancer screening: HPV and Pap tests

Cervical cancer screenings look for abnormal cells or HPV (human papillomavirus) infections that may lead to cancer over time. Screening may include Pap tests (Pap smear) or HPV tests. Depending on age and circumstances, these tests may be done in a healthcare provider’s office or, in some cases, at home using approved kits.

For women and other individuals with a cervix at average risk, the American Cancer Society recommends regular screening begins at age 25 and continues until at least age 65. The U.S. Preventive Services Task Force (USPSTF) recommends cervical cancer screening starting as early as 21. Talk with your doctor to decide when you should begin screening.

These tests are usually done as part of a routine visit with a healthcare provider and generally do not require a separate referral.

Lung cancer screening: Low-dose CT scans

Lung cancer screenings use low-dose CT scans to look for early signs of cancer in adults considered at higher risk, such as those with a significant smoking history. This type of screening typically requires a conversation with a healthcare provider and a referral to determine eligibility.

For adults who have at least a 20 pack-year history, and currently smoke or have quit within the last 15 years, the U.S. Preventive Services Task Force (USPSTF) recommends yearly lung cancer screening for those between 50 and 80 years old.

“Pack-year history” is a way to measure the amount a person has smoked over an extended period. A pack-year history is calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person smoked. For example, 20 pack years is equal to smoking 1 pack per day for 20 years, or 2 packs per day for 10 years, and so on.

Current lung cancer screening recommendations generally do not include adults who have never smoked, unless they have other significant risk factors.

Learn more about What to ask your doctor about lung cancer screening.

Prostate cancer screening: PSA test

Prostate cancer screening often involves a PSA (prostate-specific antigen) blood test as the first step. The blood test is ordered through a healthcare provider and does not usually require a specialist referral.

Screening decisions are usually made through shared decision-making, taking into account age, family history, and personal preferences. The American Cancer Society recommends men start the conversation with their doctor at 50 if they are at average risk, and 45 if they are at higher risk. Those with more than one first-degree relative who had prostate cancer at an early age should speak to their doctor about screening at the age of 40.

For more information on cancer screening recommendations for early detection, visit the American Cancer Society.

How are cancer screening results interpreted?

Screening results can fall into several broad categories:

• No concerning findings
• Findings that need follow-up tests
• Results that are unclear or inconclusive

An abnormal screening result does not mean someone has cancer. It means that something was detected that needs a closer look. It is common for your doctor to recommend other tests to rule out cancer.

Keep in mind that a normal result reflects only what was seen at the time of the test. It does not mean you can’t develop cancer in the future, and no screening test catches everything. You may still need screening at regular intervals, depending on risk and age.

Which risk factors are considered when screening for cancer?

Cancer screening guidelines are developed using research and population-level data. They typically consider risk factors like your age, family history, lifestyle, and health conditions.

Age is a factor, but it is not the only factor. Many screening guidelines are organized by age, because the risk of certain cancers can increase over time. But younger adults can still be affected by cancer.