Thyroid cancer is on the rise on the United States and most of the increase is due to PTC, although the authors write that it is debatable whether the increase is caused by an enhanced risk of cancer or an increase in detection. Obesity is recognized as a risk factor for a variety of cancers, the authors provide as study background.
"Our study shows that those patients with increasing BMI have a progressively increasing risk in presenting with late-stage PTC. This finding is especially seen in the obese and morbidly obese populations," the researchers comment.
Avital Harari, M.D., and colleagues at the UCLA David Geffen School of Medicine, Los Angeles, reviewed the medical records of all patients older than 18 who underwent total thyroidectomy (removal of most or all of the thyroid gland) as an initial procedure for PTC or its variants from January 2004 through March 2011.
The final analysis included 443 patients with an average age of 48.2 years. Patients were divided into four BMI (body mass index) groups: normal (18.5-24.9), overweight (25-29.9), obese (30-39.9) and morbidly obese (?40).
"Greater BMI was associated with more advanced disease stage at presentation. Specifically, the obese and morbidly obese categories presented more as stage III or IV disease," according to the study results.
Researchers also note the obese and morbidly obese groups also presented with a higher prevalence of PTC tall cell variant, "suggesting that these groups have a higher risk of more aggressive tumor types."
"Given our findings, we believe that obese patients are at a higher risk of developing aggressive thyroid cancers and thus should be screened for thyroid cancer by sonography, which has been shown to be more sensitive in detecting thyroid cancer than physical examination alone," the authors conclude.
In an invited critique, Quan-Yang Duh, M.D., of the University of California, San Francisco, writes: "Harari and colleagues from UCLA (University of California, Los Angeles) showed us one more reason to be concerned about the current obesity epidemic – obese patients have more advanced thyroid cancer."
Duh continues: "This parallel increase in the rates of obesity and thyroid cancer is intriguing, but without a much larger population study, we cannot determine whether obesity causes thyroid cancer. However, the authors found that higher body mass index is associated with a later stage of thyroid cancer."
"For obese patients with papillary thyroid cancer, the bad news is that the cancer is likely to be more advanced. The good news is that thyroid operation remains safe even in obese patients with advanced disease," Duh concludes.