Researchers who found a strong correlation between large head circumference and cancer risk in Cowden syndrome patients are encouraging people with big heads to see a genetic counselor regarding cancer screening.
Scientists from the Cleveland Clinic’s Genomic Medicine Institute looked at 127 patients who carry the genetic mutation that causes Cowden syndrome, a condition associated with an increased risk of breast, thyroid, and uterine cancers. Among these patients, large head circumference was the most common clinical trait.
“What this means is that people with big heads – defined as greater than 58 centimeters in men and 57 centimeters in women – should see a genetic counselor to determine whether they should be screened for colon, breast, thyroid, and uterine cancers,” lead researcher Charis Eng, M.D., Ph.D., Hardis Chair of the Genomic Medicine Institute in Cleveland Clinic’s Lerner Research Institute, said in a statement from the clinic.
The study, published in the December issue of Gastroenterology, found that 74.8 percent of Cowden patients exhibited large head size, much more than the previous medical literature estimate of 25 percent, the clinic noted.
Researchers also found a similar association with colon polyps, which had not been a strong indicator of Cowden, according to the clinic. Scientists discovered that the presence of gastrointestinal polyps in these patients signifies an increased risk of early colorectal cancer. They should undergo routine colonoscopies starting at age 35 instead of 50, the age recommended for the general population, researchers said.
“Before these findings, I told my patients that there’s no need for unusually aggressive colon cancer screenings,” Eng said. “As we can see now from our research, however, we need to start screening these patients for colon cancer in their early- to mid-30s at the latest – and it should be annual screenings, not every 10 years.”
About 1 in 200,000 people are affected by Cowden syndrome; because the condition is difficult to diagnose the exact prevalence is unknown. The Cleveland Clinic study may change diagnosis by including gastrointestinal polyps and head circumference among the diagnosis criteria, the clinic noted. Under previous guidelines, 16.5 percent of this study's patients would have erroneously escaped Cowden diagnosis upon enrollment, the clinic said.
The research, the largest, most targeted study to date regarding the evaluation of benign and malignant growths in the GI tract of Cowden patients, also links mutations of the PTEN gene — a known cause of Cowden syndrome — to an increased risk of early colorectal cancer at a rate 200 times as common as that of the general population.
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