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The Difference Between a Prostate Exam vs. Colonoscopy

Male and female characters inspecting and study proctology. Doctor examine intestines

Prostate cancer and colorectal cancer are two of the most common cancers in American men. PSA screening and colonoscopy procedures are screening tests performed to detect cancer early and prevent cancer deaths.

Please continue reading to learn more about prostate cancer screening with a prostate exam or PSA test and colorectal cancer screening with stool tests or colonoscopy.

Prostate Cancer in Men

Prostate cancer is the second leading cause of cancer death in men after skin cancer. The risk of prostate cancer increases with age. Men over the age of 65 are more likely to develop prostate cancer. Risk factors also include African-American or Caribbean ethnicity and having a first-degree family member (father or brother) with prostate cancer, especially a family member with prostate cancer at an early age (younger than 65 years).

Prostate Cancer Screening

The American Cancer Society recommends that prostate cancer screening starts at age 50 for men at average risk, at age 45 for men at high risk, and age 40 for men at even higher risk of prostate cancer. 

Physicians perform prostate cancer screening in two ways:

  1. Digital rectal examination: The healthcare provider inserts a gloved, lubricated finger into the rectum to manually palpate the prostate gland and determine if it feels abnormal. While many patients undergo prostate examination with a digital rectal exam, it is not a foolproof way to detect prostate cancer. 

    The U.S. Preventive Services Task Force does not recommend a digital rectal examination for routine screening. However, the American Urological Association and the American Cancer Society recommend a digital rectal examination (DRE) as an option for prostate cancer screening in men between the ages of 50 and 54.
  2. Prostate-specific antigen (PSA) test: This blood test checks prostate-specific antigen (PSA) levels in the blood. The prostate gland produces this substance PSA. PSA levels can be high in men who have prostate cancer. 

How often should men be screened for prostate cancer? 

For most men, getting a prostate-specific antigen (PSA) blood test every 2-3 years is enough. Your doctor may recommend getting PSA tests more or less frequently depending on your previous PSA test results and your risk factors for prostate cancer.

Colorectal Cancer in Men and Women

Colorectal cancer starts in the colon (large intestine) or rectum. Risk factors for colorectal cancer include being overweight or obese, lack of physical activity, a diet rich in processed meats or red meats, heavy alcohol use, smoking, older age, and a personal or family history of colorectal cancer or colon polyps (small growths).

Colon Cancer Screening

The American Cancer Society recommends that men and women at average risk of colorectal cancer start regular screening at age 45 (may be even earlier if you have predisposing genetic conditions) and continue until age 75. From age 76 to age 85, colorectal cancer screening should be performed based on the person’s general health status, family history, prior screening results, and life expectancy. Screening for colorectal cancer is not recommended after age 85.

Physicians perform the following tests for colon cancer screening:

Stool Tests: 

  • Highly sensitive guaiac-based fecal occult blood test (gFOBT) yearly, or…
  • Highly sensitive fecal immunochemical test (FIT) yearly, or…
  • Multi-targeted stool DNA test (MT-sDNA) every 3 years

Imaging Tests:

  • Colonoscopy every 10 years, or…
  • Flexible sigmoidoscopy every 5 years, or…
  • CT colonography every 5 years

Women and men who choose to have tests other than colonoscopy for colon cancer screening should have a colonoscopy done if the results are abnormal on any of the other tests.

What is a colonoscopy?

A colonoscopy is an imaging test that is one of the most powerful methods to detect colorectal cancer in the early stages and prevent cancer-related death. During this screening test, a long, flexible tube with a tiny camera attached to its tip is inserted into the rectum. This allows physicians to examine the colon and rectum visually.

Is a digital rectal exam part of a colonoscopy?

All colonoscopies begin with a digital rectal exam. It is standard practice to perform a digital rectal examination before inserting the colonoscope (flexible tube) into the rectum. The DRE not only evaluates but also helps to lubricate the rectum. However, endoscopists or general surgeons performing a colonoscopy to screen for colorectal cancers often do not perform a dedicated prostate examination at the start of the colonoscopy to also screen for prostate cancer. 

This is a missed opportunity because a digital rectal examination and prostate examination performed at the time of colonoscopy would simultaneously screen for two of the three most common cancers in American men. 

The importance of prostate and colorectal cancer screening

Cancer screening saves lives. It can help with the early detection of prostate cancer and colorectal cancer early before the tumor has grown in size or the cancer has spread to other parts of the body. Women and men diagnosed with early-stage cancer are more likely to be treated successfully. 

Talk to your doctor about the appropriate age to start cancer screening with PSA tests in men and colonoscopy in men and women. 


  1. https://www.cancer.org/healthy/cancer-facts/cancer-facts-for-men.html
  2. https://www.cdc.gov/cancer/prostate/basic_info/screening.htm#
  3. https://www.giejournal.org/article/S0016-5107(17)32119-3/fulltext