MARCH IS COLORECTAL CANCER AWARENESS MONTH in the United States. Today, we look at the relationship between height and the chances of getting colon cancer. I also want to look at better-known risk factors for the disease before turning to potential risk-reducing maneuvers you can pursue.
Colon and rectal cancers are common. For example, in the United States, the lifetime risk of developing colorectal cancer is about one in four for men and women.
In the USA, colorectal cancer is the third most common cause of cancer-related death in men and women and the number two cause of cancer death for men and women combined. This incidence translates to over 52 000 cases this year.
The good news? The death rate has been dropping for decades. We tend to catch colorectal cancer early because of screening interventions, and treatment has also improved.
The bad news? Despite this overall reduction in the death burden, deaths from colorectal cancer among people younger than 55 increased one percent per year from 2008 to 2017.
Height and colon cancer risk
Johns Hopkins Medicine (USA) scientists recently reported the most extensive study suggesting that taller adults are more likely (than shorter ones) to get colon or rectal cancer or precancerous colon polyps.
This analysis of a collection of studies, or meta-analysis, evaluated 47 international, observational studies. These research investigations included over 280 000 cases of colorectal cancer and over 14 000 cases of colorectal adenoma.
Adenomas represent about 10 percent of colon polyps. Most of the time, the polyps are small — usually under one centimeter in diameter — and have a small potential for becoming cancer. The remaining 10 percent of adenomas are bigger than one centimeter and approach a 10 percent chance of containing cancer.
Recognizing that the definition of tallness varies worldwide, the researchers compared the highest versus the lowest height percentiles of various study groups. Here are the results:
People within the highest percentile of height had a 1.24-times higher risk of colorectal cancer than the lowest percentage. The researchers also provide this estimate:
Every 4-inch increase in height appeared associated with a 1.14-times increased risk of developing colorectal cancer and 1.06-times increased risk of having adenomas.
The study authors conclude: “Greater adult height is associated with a higher risk of colorectal cancer and adenoma. Therefore, height should be considered as a risk factor for colorectal cancer screening.”
You may be calculating your own risk. The US Centers for Disease Control and Prevention offers that the average height in the USA is 5 feet, 9 inches for men and 5 feet, 4 inches for women.
We get a 1.14-times increase in the risk of colorectal cancer and a six percent higher risk of colorectal adenomas for a man who is 6 feet, 1 inch, or a woman who is 5 feet, 8 inches, or taller.
Speaking with Sciencedaily.com, co-first author Elinor Zhou, M.D. offers this explanation: “One possible reason for this link is that adult height correlates with body organ size. More active proliferation in organs of taller people could increase the possibility of mutations leading to malignant transformation.”
Height and colorectal cancer: My take
First, the study shows an association and does not establish a causal relationship between height and colorectal cancer risk. Second, while this study shows height may be a risk factor for colorectal cancer, not all studies have found this result.
Some perspective: The authors note a 14 percent increase in risk. But I think we all tend to better understand absolute changes (instead of relative ones).
So if we take a 14 percent increase on four percent incidence (for those at average risk of colorectal cancer in the USA), we get a 0.5 percent absolute increase in risk. Not a lot, but hopefully a nudge to get colorectal cancer screening (whether a stool test or a more invasive procedure).
Finally, the study authors report no conflicts of interest.
Potential risk-reducing maneuvers
The American Cancer Society reminds us of these potential risk-reducing maneuvers:
- Get screened for colorectal cancer. The American Cancer Society recommends testing starting at age 45 for people at average risk. Some colorectal screening tests can also find and remove precancerous growths (polyps) in the colon or rectum. Polyps are not cancer, but cancer can start in the polyps over time. Removing them lowers the risk of cancer. Talk to your health care provider about when you should start screening and which tests might be best for you.
- Eat lots of vegetables, fruits, and whole grains.
- Get regular exercise.
- Take control of your weight.
- Don’t smoke. If you smoke and want to quit or know someone else who does, see the American Cancer Society guide to quitting tobacco, or call us at 1–800–227–2345. Getting help increases your chances of quitting.
- Avoid alcohol. It is best not to drink alcohol. But if you do, the American Cancer Society recommends no more than two drinks a day for men and one drink a day for women. A single drink equals 12 ounces of beer, 5 ounces of wine, or 1½ ounces of 80-proof distilled spirits (hard liquor).
- I will add one of my own. Get adequate sleep.