Taller adults may be more likely than shorter ones to develop colorectal cancer or precancerous colon polyps, according to a new meta-analysis published in Cancer Epidemiology, Biomarkers & Prevention. While the association between taller height and colorectal cancer has been previously investigated, the researchers say those studies offered conflicting results, used inconsistent measures of height and did not include the risk of adenomas.
“This is the largest study of its kind to date. It builds on evidence that taller height is an overlooked risk factor, and should be considered when evaluating and recommending patients for colorectal cancer screenings,” said Associate Professor Gerard Mullin, MD. Greater height is still not proven to be causative, nor is it a great a risk factor as genetics, he and his team cautioned. However, it does add to long-standing evidence linking height to colorectal cancer risk.
“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,” said co-first author Elinor Zhou, MD.
The researchers first identified 47 international, observational studies involving 280 660 cases of colorectal cancer and 14 139 cases of colorectal adenoma. They also included original data from the Johns Hopkins Colon Biofilm study, which recruited 1459 adult patients undergoing outpatient colonoscopies to investigate the relationship between cancer and biofilm on the colon.
Because the definition of tallness differs around the world, the researchers compared the highest versus the lowest height percentile of various study groups. “The findings suggest that, overall, the tallest individuals within the highest percentile of height had a 24% higher risk of developing colorectal cancer than the shortest within the lowest percentile. Every 10-centimeter increase (about 4 inches) in height was found to be associated with a 14% increased risk of developing colorectal cancer and 6% increased odds of having adenomas,” said A/Prof Mullin.
In the US, the average height for men is 175.3cm, and for women it is 162.6 inches. This means men who are 185.4cm and women who are 172.7cm (10cm above the average US height) or taller are at a 14% increased risk of colorectal cancer and a 6% increased risk of adenomas.
The percentage results were adjusted for known risk factors of colorectal cancer, including non-modifiable factors such as age, familial colorectal cancer history and a personal history of chronic inflammatory bowel disease. Though not directly comparable due to differences in measurement scale, tallness may impart an order of magnitude of colorectal cancer risk similar to better-known modifiable factors such as cigarette smoking, moderate alcohol consumption and high processed red meat intake. At present, gastroenterologists focus on genetic and age-related risks for colorectal cancer screenings recommendations.
While colorectal cancer is the third most common cancer in both men and women in the US, fewer people are diagnosed with colorectal cancer each year has dropped overall since the mid-1980s, mainly due to prevention and screening. However, the downward trend is mostly in older adults. Among adults under 50, colorectal cancer deaths have increased 2% per year from 2007 to 2016, an as yet unexplained phenomenon.
“Greater awareness by the public and government will help promote more interest and funding for more research, which ultimately could change guidelines for physicians to consider height as a risk for cancer,” said A/Prof Mullin. “There are well-known modifiable dietary associations for colorectal cancer, such as processed red meats and smoking, but guidelines currently are fixated on family history, and height is clinically neglected when it comes to risk screening.”
Dr Zhou says more research is needed to define particular taller populations at risk for colon cancer. “For instance, tall athletes and individuals with inherited tallness, such as those with Marfan syndrome, could be screened earlier and the impact of height further explored,” she said. “We need more studies before we can definitively say at what height you would need earlier colorectal cancer screening.”
Source: John Hopkins Medicine
