Young-onset Colorectal Cancer ASCO Education

The incidence of colorectal cancer among people under 50 is rising. In this ASCO Education podcast episode, medical oncologist Nilofer Azad (Johns Hopkins Medicine) and epidemiologist Caitlin Murphy (UT Southwestern Medical Center) discuss risk factors, screening, and treatment.
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Air Date: 7/28/2021
 
TRANSCRIPT
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SPEAKER: The purpose of this podcast is to educate and inform. This is not a substitute for medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.
NILO AZAD: Welcome to the ASCO learning podcast episode focusing on early-onset colorectal cancer. My name is Dr. Nilo Azad, and I'm a medical oncologist and Associate Professor of Oncology at Johns Hopkins Medicine. I'm joined today by Caitlin Murphy, an Assistant Professor of Epidemiology at the University of Texas Southwestern Medical Center. We wanted to start today with a patient case, just to give a little bit of context about the kinds of patients that we are dealing with.
A year ago, a patient presented to my clinic who was 32 years old. She was having significant symptoms of rectal obstruction. She was having trouble going to the bathroom. Her bowel movements were difficult. She was having bloody stools, and she had gone to see a gastroenterologist who had done a colonoscopy, biopsied her tumor, and found that she had adenocarcinoma of the rectum.
Now, luckily, at that time, she didn't have any metastatic disease. But her tumor was quite large, 15 centimeters in size, and so we decided to move forward with doing chemotherapy in the neoadjuvant setting. She got aggressive chemotherapy with FOLFOX for three months. And when we did a scan, unfortunately, we found that the tumor had grown.
Now, she still didn't have any disease outside of the rectum but, during that time, we had gotten some molecular testing back which showed that the patient had mismatch repair deficiency or microsatellite insufficiency. So we decided to try something a little outside of the box at that time, where we started treatment with immunotherapy.
She had a dramatic response to immunotherapy. Her tumor shrank. And, six months later, she went to surgery and, though on scan it still looked like she had a large tumor, it turned out that that tumor was only scar and that she'd had a complete response.
She came back to see me, last week, in clinic. She looks fantastic, and she's moving forward with planning for a family with her husband. So, Dr. Murphy, can you tell us a little bit about the trends in early-onset colorectal cancer incidence in the US and globally?
CAITLIN MURPHY: Of course. I'll start, first, by talking about trends in early-onset colorectal cancer in the United States. Incidence rates began increasing here in the early 1990s and have nearly doubled over time, from about eight cases per 100,000 persons in the early 1990s to 16 per 100,000 persons in today. The largest increases have occurred in 40 to 49-year-olds. They account for about 80% of all cases.
And we've also noticed that incidence rates of rectal cancer versus rates of proximal colon or distal colon cancers have been the largest increases in incidence. We've also seen a similar increase in local and distant stage disease.
And, to me, one of the most compelling observations that we've made is that incidence rates have increased successively across generations, or about the year that you were born. There's a very clear and marked increase in incidence rates starting with persons born in and around 1960, or who we sometimes call Generation X. Epidemiologist like to call this a birth cohort effect because essentially we see incidence rates increasing across