In our Ask a Doc series, we sit down with physicians and other clinical experts across our networks, including at Allegheny Health Network, for a chat on an important health topic. In this edition, we’re talking about colon cancer screening with Dr. Sherif Rizk.


The good news: Americans’ awareness about when, why and how to be screened for colorectal cancer is approaching 100%.

The not-as-good news: Knowing is only half of the battle.

Nearly all of us understand that colorectal cancer exists and that screening is available and effective. Yet more than 20 million American adults who should be screened simply haven’t done it. When the American Cancer Society asked unscreened adults why they hadn’t gone through with the testing, their reasons included:

  • Concerns about cost of the test (in money, time and effort)
  • Impression that screenings are difficult or painful
  • Misconception that screenings are only for people with symptoms
  • Incorrect assumption that having no family history of colon cancer means they’re not at risk

Amanda Changuris (AC): Dr. Sherif Rizk, as an experienced colorectal surgeon with the Allegheny Health Network, what is the difference between a screening and a diagnostic colonoscopy, and what would you like this unscreened population to understand?

Dr. Sherif Rizk (SR): A diagnostic colonoscopy is recommended to diagnose the common causes of gastrointestinal ailments such as bleeding with bowel movements or changes in bowel habits. A diagnostic colonoscopy is guided by the patient’s symptoms at all ages. In sharp contrast, a screening colonoscopy is recommended for individuals who feel perfectly fine. It’s used in an effort to prevent or detect colorectal cancer before symptoms develop. The timing of the screening colonoscopy is determined by the patient’s age and risk profile. The guidelines are set to maximize the risk to benefit ratio for the individual based on his or her risk factors.

Colorectal cancer is a preventable and curable cancer. During a colonoscopy, if we find an adenomatous polyp (pre-cancerous growth), we remove it at the same time. That’s one of the advantages of a colonoscopy. It can be a screening, but it can also be a form of treatment because while we’re making the diagnosis of a polyp, we remove the polyp at the same time. 

If we find a polyp and remove it, we’ve prevented a cancer three, five or even ten years down the road.

Screening Guidelines and Recommendations

Nurse Erin Scott, West Penn Hospital

Nurse Erin Scott prepares for a colonoscopy at West Penn Hospital.

AC: So who needs to get a colonoscopy and when? What are the accepted guidelines and recommendations?

SR: There are two major categories. The first category is normal-risk patients. The other group is at high risk for colorectal cancer. The major risk factors are family history of colorectal cancer, ulcerative colitis, Crohn’s disease, a personal history of colorectal polyps, and some rare hereditary colon cancer conditions. Also, having had a personal history of colorectal cancer in the past is a strong risk factor for developing it again.

The guidelines for screening the general population, if you’re on the normal risk side and you do not have symptoms (see sidebar), [are] at the age of 50, you get your baseline colonoscopy.

The guidelines for the high-risk group are to have the first colonoscopy at age 40, or 10 years younger than the [age when your] youngest family member developed it – whichever is younger. So if a mother developed colon cancer at the age of 45, we recommend the first colonoscopy at the age of 35 for her son or daughter.

Colon cancer is not gender specific. If your mother or father has it, your risk goes up whether you’re male or female. The lifetime risk of developing a colorectal cancer is about 5%. The risk is lower under the age of 40, and increases with age.

AC: In terms of family history and calculating risk, are all family members equal?

SR: A person with a parent having colon cancer is quantitatively considered to be higher risk than, say, an uncle or an aunt having colorectal cancer. It’s not a true mathematic equation, but for the sake of discussion, we try to equate one first-degree relative with two second-degree relatives. So having two uncles who’ve had colon cancer would be equal in terms of added risk to having one parent with colon cancer.

AC: Let’s fast-forward a bit and say I’ve just turned 50 and had my first colonoscopy. What’s next?

SR: If the first one shows three or more polyps, we’ll recommend repeating every three years. If the first one shows no polyps, we recommend repeating every 10 years. The reality of life is there are a lot of people who fall in between. So if someone has one polyp and the preparation is not that clean (read: there was low visibility in the colon), we might recommend another colonoscopy in the range of five to 10 years.

Depending on the number of risk factors, we might add another test annually – a fecal occult blood test – if there are no polyps on the colonoscopy. If they have any polyps and they’re high risk, we’ll probably do another colonoscopy in two to three years. Patients with hereditary conditions such as Lynch Syndrome or polyposis get screened more frequently – typically every 12 to 18 months.

For patients who have had a portion of their colon removed due to cancer, life-long surveillance with colonoscopies is necessary. Even after 5 years (when patients are generally considered to be cured), colonoscopies are done to detect the development of a second (new) colorectal cancer.

Preparing for Your Colonoscopy

AC: Getting ready for a colonoscopy has quite the reputation for being unpleasant and difficult. What tips can you offer to help patients get through the process?

Drink all of the Preparation Liquid

SR: The bowel preparation (prep) is essentially a colonic flush, and you flush the colon over the course of three or four hours. You have to drink a whole gallon of liquid in that time. Obviously a lot of people have difficulty – myself included – in drinking that kind of volume, so there are many other preparations that we alternatively use that are much smaller in volume. Whatever you’re given, make sure you drink all of it and observe the clarity of the output. The quality of the colonoscopy is greatly affected by the clarity of the colonic wall.

Pace Yourself

SR: Second, because of the sheer volume [of preparation liquid], sometimes people will be very motivated and drink the first quart or two quarts and then they feel nauseous and may vomit. I recommend you try to pace yourself. If you feel nauseous, back off for a few minutes until it starts working its way down the intestines and you feel a little better. Sometimes if people vomit, they think “that’s all I’m going to do” and they may be halfway through the gallon of liquid. They should persist and not give up on it.

Start Preparing in the Afternoon

SR: The day before the procedure, try to leave work a little bit early so you can start in the late afternoon and have a clear liquid dinner. That way you won’t be up moving your bowels all night. People who wait too long, have a full dinner, go out, and then start the prep at 8:00 or 9:00 p.m. and are  up half the night running to the bathroom, have more of a difficult time with it than those who start earlier.

Eyes on the Prize

AC: So having a colonoscopy is no vacation, but again – we’re talking about a screening/treatment that ideally prevents a cancer diagnosis. And even if prevention isn’t possible, early-stage colon cancers tend to be treatable, right?

SR: For stage-one colorectal cancer, long-term survival is the same as the overall population; that’s why you want to get screened. Even if it’s not prevented, catching it early means it may not have an impact on your long-term survival. In fact, surgery is the mainstay treatment for colorectal cancer, and the majority of patients with early diagnosis of colorectal cancer will not require any additional treatment (such as chemotherapy or radiotherapy).

AC: As a daughter and granddaughter (x3) of colon cancer patients — some who survived and others who didn’t — I’m firmly in the “ounce of prevention is worth a pound of cure” camp on this one.

Take these guidelines to heart and talk to your doctor about when you should be screened. Together, you can discuss your risk factors and come up with a plan to keep your colon cancer-free.