What’s the Difference Between a Prostate Exam and a Colonoscopy?
A prostate exam and a colonoscopy are both routine health screenings, intended to help doctors check for certain conditions and diseases, like cancer. But if you’re feeling perfectly healthy and don’t have symptoms, you may be tempted to delay or skip your screening. But routine screenings are an important part of staying healthy.
“Routine screenings, in the vast majority of times, will be reassuring and yield no concerning results,” says Adam Kibel, MD, a Mass General Brigham urologist and chair of Urology. “But sometimes they allow us to identify disease early, when it's still treatable, as opposed to too late, when it's not.”
Dr. Kibel and Daniel Chung, MD, a Mass General Brigham gastroenterologist, explain what to expect with each of these screenings, and when you should talk to your doctor about getting one. Dr. Kibel conducts research and cares for patients at Brigham and Women’s Hospital. Dr. Chung leads the High-Risk Gastrointestinal Cancer Genetics Program and cares for patients at Mass General Cancer Center and the Division of Gastroenterology at Massachusetts General Hospital.
What is a prostate exam?
The prostate is a walnut-shaped organ found in men and people assigned male at birth (AMAB). It’s located beneath the bladder and plays a large role in reproduction.
As you age, your prostate often increases in size and can have a higher risk of cancer. A prostate exam is a health screening that allows your doctor to check your prostate and understand if there’s anything to be concerned about. They mostly want to check for prostate cancer, but also look for non-cancerous conditions, like benign prostatic hyperplasia (BPH), which enlarges your prostate and can cause complications.
Digital rectal exam
Most people who undergo a prostate exam have a digital rectal exam, or DRE.
With a DRE, your doctor inserts a gloved, lubricated finger into your rectum and feels your prostate. They check for any abnormalities, like lumps or if your prostate is enlarged. The exam is extremely short, usually lasting about 10 seconds.
“A rectal exam causes mild discomfort, but the search should not be very painful. If it is, that could be a sign that there's something going on,” says Dr. Kibel.
Your doctor will discuss the results of your exam at your appointment. If they find anything to be concerned about, they may refer you to a urologist, a doctor who specializes in the urinary system and treats conditions that affect the prostate.
Prostate-specific antigen (PSA) test
Your doctor may also recommend a PSA test, which is a blood test that measures the level of prostate-specific antigen in your blood. Your PSA level indicates how likely it is that you have or will develop prostate cancer.
For a PSA test, your doctor draws a small sample of blood and sends it to a lab to check your PSA levels. They call you or share the results on your Patient Gateway portal.
The results won’t tell you if you do or do not have prostate cancer. If your PSA levels are very low, it’s unlikely that you currently have prostate cancer or will develop it in the future. If your PSA levels are high, your doctor may refer you to a urologist or recommend you have more frequent prostate exams.
When should I get a prostate exam?
For most people, Dr. Kibel recommends having a rectal exam and PSA blood test starting at 50 years old. The results of that initial prostate exam tell your doctor how frequently you should continue to have exams moving forward.
Risk factors for prostate cancer
There are factors that can affect your risk of getting prostate cancer. Your risk may be increased if you:
Are over 50 years old
Have a family history of prostate cancer.
Have certain gene variants. Men or people AMAB who have changes to their BRCA1 or BRCA2 gene are at increased risk of prostate cancer.
Have African ancestry. Research shows that Black men are not only more likely to develop prostate cancer, but also are more likely to have an aggressive type and are more likely to die from the disease compared to white men. Programs like the Prostate Cancer Outreach Program, part of Mass General Brigham’s United Against Racism initiative, are working to combat these disparities.
If you have an increased risk of prostate cancer, Dr. Kibel recommends you have your first prostate exam earlier, at the age of 40.
“We're doing studies to try and incorporate genetic testing into our evaluation of patients to see how intense the screen needs to be,” Dr. Kibel adds. He and colleagues are leading research to see if genetic testing and magnetic resonance imaging (MRI) can help improve detection rates of prostate cancer.
Prostate symptoms to watch out for
You might experience certain symptoms that mean you should have a prostate exam earlier. Dr. Kibel notes that these may not necessarily be symptoms of prostate cancer, and could instead be warning signs of another condition.
Talk to your primary care provider (PCP) if you:
Get up more frequently at night to urinate
Strain to urinate
Have to go again soon after urinating (called double voiding)
See blood in your urine
What is a colonoscopy?
Like prostate exams, a colonoscopy is a screening test that can help detect cancer earlier. However, the two exams are very different.
A colonoscopy primarily screens for colorectal cancer, a term that includes both colon cancer and rectal cancer. Your colon and rectum are part of your large intestine.
“Colorectal cancer is the fourth most common cancer diagnosed and is the second leading cause of cancer-related deaths in the United States,” says Dr. Chung. “We know that screening can reduce the number of deaths related to colorectal cancer — but not enough people are getting screened.”
During a colonoscopy, a health care provider uses a thin tube with a small camera and light to check for cancer and also polyps, or abnormal growths, inside your rectum and your entire colon. These polyps can be precancerous, meaning they may eventually transform into cancer cells and lead to colorectal cancer. Some institutions like Mass General Brigham use computer-aided detection systems — a form of artificial intelligence — during the exam to help the provider better detect polyps.
“Not every polyp will become cancerous, but we remove polyps that we see during a colonoscopy,” explains Dr. Chung. “There is very good evidence that if you do this, you can prevent colorectal cancer from developing in the future.”
A colonoscopy usually takes less than 30 minutes. You’ll be sedated, so you won’t feel anything during it or remember much afterward.
While there are other screening tests for colorectal cancer, such as a stool or blood test, they don’t remove polyps and aren’t as accurate as a colonoscopy. However, Dr. Chung notes that they may be more appropriate for certain patients, who can’t take time off work or set up a ride home, for example. “There should be a discussion between the provider and patient about the pros and cons for each approach. The best test is the test that gets done,” he adds.
Preparing for a colonoscopy
Before your colonoscopy, you’ll need to do a “bowel prep,” which essentially cleans out your intestines to help your provider see polyps more easily during your exam.
The day before your colonoscopy, you switch to a clear liquid diet with no solid foods, but you can still have things like broth, Jell-O®, and juices. You also take a laxative medication, which can be a liquid or pill, typically in what’s called a split prep — where you take half of the medication in the late afternoon before your colonoscopy, and the second half closer to your appointment.
While colonoscopy prep can be a bit burdensome, Dr. Chung emphasizes that it is critically important. “If the bowel is not well cleaned out, then we can’t see the lining of the colon well, and there is a greater chance that growths may be missed.”
After your colonoscopy
Once your colonoscopy is over, you recover from the exam for a short time to make sure you’re feeling comfortable, and you learn about your results. Because you were sedated, you’ll need to set up a ride home and likely take the day off from work. You can return to eating solid foods relatively soon after your appointment.
If your provider found anything abnormal, they take a sample and send it to the pathology lab to check if there’s any evidence of cancer. You should find out your results in about a week or 2. If the sample may be cancerous, your doctor will discuss next steps with you.
When should I get a colonoscopy?
Research shows that colorectal cancer is increasing in younger people. The Centers for Disease Control and Prevention (CDC) now recommend having your first colonoscopy at age 45. However, that’s only if you’re relatively healthy and not at higher risk.
You may need to be screened earlier or more often if you have:
A family history of colon or rectal cancer
Any prior polyps found or had any prior cancer
Chronic inflammatory bowel disease (IBD)
Rectal bleeding, as this can be a sign of colorectal cancer
Dr. Chung notes there are several lifestyle factors that can increase your risk of colorectal cancer. While providers won’t factor these into your screening recommendation, you can take steps to improve your lifestyle and reduce your cancer risk.
Here’s what you can do to help reduce your risk of colorectal cancer:
Eat a high-fiber and low-fat diet, as well as reducing how much red meat you eat.
Drink less alcohol.
Aim for a healthy weight. Being overweight or having obesity increases your risk of colorectal cancer.
Talk to your primary care provider about what health screenings may be right for you
Your age plays a big role in when you should get a prostate exam or colonoscopy, but there may be other genetic or lifestyle factors that increase your risk of cancer. It’s important to get screened so you can catch any disease or condition earlier on, when it’s more treatable. Talk to your PCP about what health screenings may be right for you.
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