Colon Cancer: The Latest Research and Screening Options
The American Cancer Society estimates 97,220 new cases of colon cancer and 43,030 new cases of rectal cancer will be diagnosed in 2018. It is the third leading cause of cancer-related deaths in the United States, but it is one of only a few cancers that may be prevented through screening, and when found at an early age it can frequently be treated.
The risk of getting this type of cancer increases with age and can be influenced by family history, physical inactivity, obesity, smoking, heavy alcohol use, diabetes, inflammatory bowel disease, and a diet high in red meats and processed foods.
Read or listen to our interview below with Dr. Jesse Moore, a colon and rectal surgeon at the UVM Medical Center and an associate professor at the Larner College of Medicine. He tells us the risks and how to get tested to catch this cancer early.
Colon cancer: Who’s at risk?
Colon and rectal cancer is, like you mentioned, the third most common cancer out there. The people who are at highest risk are a very, very small proportion of our population who have a known inherited predisposition, a genetic abnormality. Those patients only make up about one to maybe as high as five percent of patients who have colorectal cancer, and those genetically inherited types of colorectal cancer usually come under one of two different types, either patients who have a history of familial adenomatous polyposis, or Lynch syndrome, which is also sometimes referred to as hereditary nonpolyposis syndrome.
But again, those are a very small proportion of patients out there, and they’re usually in families who have a strong family history, multiple members of the family, particularly with cancers that happen at a younger age. The vast majority, 70 to probably 90/95% of our patients with colorectal cancer are not related to some known genetic mutation, and are from a spontaneous mutation in that patient. So we call those sporadic cancers.
There are some things that we know can increase your risk for getting a colorectal cancer. Probably the biggest thing is a family history of a first-degree relative, meaning a parent, or a sibling, or unfortunately nowadays, a child would increase your risk.
So, if you have familial adenomatous polyposis or Lynch syndrome your risks of getting cancer in your life are very high, upwards of 80 to 100%. If you don’t have one of those, you’re walking around, you’re minding your own business, your risk of getting a cancer in your lifetime is about 6%. If you have a history of a first-degree relative that risk goes up two times. So it doubles to about 12%. Again, family history, even outside of a known genetic syndrome, is the strongest thing that can increase your risk. If you have multiple family members then that risk is going to go up, and if your family member has their cancer at a very young age, say before the age of 50, then your risk of getting a cancer also is going to go up higher than that 12%.
In terms of some of the other risk factors that you spoke about, physical inactivity, obesity, smoking, heavy alcohol use, those things do increase risk but it’s only a very small percentage, in that that risk is usually seen when we look at large populations of patients and say, okay, if you have a population of people that eats a lot of red meat, or has higher alcohol consumption you’ll see very small increases at the population level.
I think it’s always good advice to get regular exercise, to eat red meats and use alcohol sparingly, and with moderation. Avoiding becoming obese, stopping smoking, those are all good general health recommendations and they will probably have some small impact on colorectal cancer.
Colon cancer screening options: Where do I start?
First thing first. Somebody that’s worried about getting colon and rectal cancer, the first thing is to know their family history, to talk with their family members, make sure they know about all the aunts, the uncles, the grandparents. Find out about causes of death, and then the other important thing is to find out if any of them have ever had a polyp, and specifically what kind of polyp.
So, if we’re to back up and say what causes colon cancer, it’s polyps that are called adenomatous. So adenomatous polyps are having an adenoma in the colon. Those polyps, over the course of about 10 years go through a series of genetic mutations that allow them to go from being a benign polyp that can’t invade to a malignant or a cancerous polyp and a cancer that can invade. Knowing if you have any family history of cancer and also knowing if anybody in your family has ever had one of these polyps will define what your risk is. If you’ve not ever had a polyp yourself, and you have no family history of ever having had a polyp on a colonoscopy, or a colon and rectal cancer, then you are what we call average risk.
For average risk patients there are a number of different screening options. They can have screening via a colonoscopy, or they can have screening via stool sample that’s tested for blood or for DNA.
That has been around for a long time and there’s very good evidence that it decreases new cases of colorectal cancer and death from colorectal cancer. The newest thing is the test that looks for DNA that has been shed into the stool, and so that’s done the same as the test that looks for blood in the stool but it’s just looking for something different. It’s only been out for about four or five years, the data is still fairly fresh, and has not been subjected to the same level of scrutiny as the other tests.
Colonoscopy: At what age do I get one?
For average risk, and remember, we define average risk as no family history or personal history of polyps or cancer, then we would start screening at the age of 50, and that’s because 90% of cancers of the colon or rectum are after the age of 50. If you have a family history, and somebody who had a colon or rectal cancer and they were young, then we typically screen family members starting 10 years before the age of diagnosis for that family member who had the cancer.
What happens if you are diagnosed with a colorectal cancer?
Well, let’s back up a step. So the symptoms that you might have sometimes would be changes in the bowel habits, potentially seeing some blood in the stool, having a change in the caliber or the size of the stool, maybe having abdominal pain, but a lot of those are late findings and they’re not all specific to cancer. But if you are having those symptoms it’s really important to review them with your primary care physician.
If you have a cancer, it’s usually going to be identified on a colonoscopy, either you had a positive stool test for blood or DNA, or you were having some symptoms, and so you’re usually sent for a colonoscopy and on that colonoscopy a biopsy is performed that confirms that there’s a cancer. The next step is usually to do a staging workup and that usually consists of CT scans, and that’s to look and make sure that the cancer hasn’t spread elsewhere into the body. And if it hasn’t then there’s usually some combination of chemotherapy, radiation, and surgery. It depends a little bit on whether we’re talking about colon or rectum, the rectum being the last six inches of the large intestinal tract.
Rectal cancer is usually when we need to combine all three of those things to cure it. If you have colon cancer you get surgery up front and then we make subsequent decisions about whether or not you need chemotherapy, after you’ve had surgery, and the colon has been removed.
I’ve heard that there’s been a recent increase in younger people being diagnosed. Can you talk more about that?
There have been at least two studies that have looked at this at the population level and it’s something that those of us who treat colon and rectal cancer have been noticing and have been talking about a lot, that we’re seeing more patients in their 30s, 40s, unfortunately, even some patients in their 20s who are getting colon and rectal cancer. And obviously this is a group of patients who are not usually thinking about cancer, they’re certainly not talking to their doctors about screening, and so what is alarming to us is that it usually gets picked up later and then it’s harder to cure it.
There are two big population studies that have confirmed what we have seen in our offices, that there is a national trend where we’re seeing more and more patients who are younger getting these cancers. The overall numbers are still very small, but at a population level there’s a significant increase. What’s interesting is that it seems to be particularly worrisome in terms of rectal cancers, so we’re seeing it more and more in younger patients with rectal cancer. Again, these are patients that are often diagnosed later in their disease and then harder to cure.
So it’s incredibly important that if patients are having any kind of symptoms, particularly if they’re young, blood in the stools, change in bowel habits, new abdominal or pelvic pains that they need to see their doctors, and what we really need to be clear about as doctors is that we don’t tell these patients it’s just hemorrhoids and send them on their way. That’s how things usually get missed is a patient gets told, “Well, it’s just hemorrhoids because you’re young, it can’t be a cancer,” and then the patient’s then six months doing Preparation H and all kinds of over-the-counter things only to find out that they had a cancer six months previously. So, it’s critically important that they get evaluated if they’re having blood in the stools, change in bowel habits, to find out exactly what’s going on.
Are there any sort of working theories about why the uptick?
Yeah. It’s interesting, it seems to be paralleling the increase in obesity in our country, and so that they mean that there’s something related to dietary or environmental exposures that’s causing it. We don’t think it’s related to screening because in patients over 50, so that group that’s getting screening, the number of incidents in that group is actually going down.
So, we’re doing a good job starting our screening at 50 and we’re dropping the rates for patients who are over 50, but in this younger group we’re starting to see this uptick. So what has got us all thinking about it at the national level is do we need to be changing our guidelines, do we need to be screening people earlier, and that’s a big discussion because screening is not inexpensive, it’s not without risk. We don’t want to put a lot of patients at risk of complications from the screening process or cause unnecessary anxiety or cost to the healthcare system.
What are the scientific questions we have to ask in order to try and learn enough that we can really figure out what is causing this, what’s behind it, what can we do to change this, this phenomenon.
I guess if you think about all the things that your risk increases for over the age of 50, are you going to start screening for everything starting at 30?
Yeah, that’s the challenge of screening, you have to ask yourself how many patients would I need to screen in order to pick up one cancer, and right now we’ve always looked at that analysis for the younger patients and the cost of screening and the risk of screening has not made sense to do until you’re 50. So you’d have to do a lot of screening at this point probably in the patients who are 30 to find one cancer and what’s the risk of all those people who go through the screening and don’t have anything? That’s what you have to consider. So it really takes careful thought and big statistics at a population level to understand what the right answer is.
What else is new in colorectal cancer research?
The big changes are probably related to the chemotherapies that we’re using. We’re seeing, in some situations, that there are new chemotherapies that can be used for colorectal cancer. There’s been a standard trio of chemotherapy, medications for the last decade or so and now some medications that work on the body’s immune system are starting to be explored so that’s exciting. It seems to only work for a small proportion of patients but it’s nonetheless it’s exciting to have new medications that we can treat some of our patients with.
There is a push in rectal cancer that’s actually looking at whether or not we can give our patients chemotherapy and radiation and in a small percentage of patients induce a complete response, meaning that the cancer totally goes away and we avoid doing a major surgery on them. We’re involved in a national research study that’s looking at answering that question, whether or not we can give our patients chemotherapy, radiation, get everything to go away and see if it actually stays away for good.
What’s your takeaway for this?
My biggest goal is for everybody to understand that this is a common cancer. I think it doesn’t get talked about as much as some of the other cancers, but it is common. It’s readily identified with screening and preventable with good screening. So, as long as people understand their risk and get some kind of screening that’s our goal.