A review of medical records of patients treated at an academic tertiary care center suggests that obese patients present to their physicians with more advanced stage and more aggressive forms of papillary thyroid cancer (PTC), according to a report published Online First by Archives of Surgery, a JAMA Network publication.
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.”
Identification and Treatment of Aggressive Thyroid Cancers
Most thyroid cancers are slow-growing, easily treatable tumors with an excellent prognosis after surgical resection and targeted medical therapy. Unfortunately, 10% to 15% of thyroid cancers exhibit aggressive behavior and do not follow an indolent course. Approximately one-third of patients with differentiated thyroid cancers will have tumor recurrences. Distant metastases are present in about 20% of patients with recurrent cancer. Approximately half of patients with distant metastases die within 5 years. The loss of the ability to concentrate radioiodine and produce thyroglobulin is a sign of dedifferentiation, which occurs in about 30% of patients with persistent or recurrent thyroid cancer. Dedifferentiation is associated with poorer responses to conventional therapy and difficulty monitoring tumor burden. Clinicians must identify tumors with more aggressive biology and treat them accordingly with more aggressive regimens. Part 1 of this two-part article, which appeared in March, described in detail the distinct types of thyroid cancer, as well as risk factors, outcomes, treatment, and prognostic factors, with a focus on thyroid cancers of follicular cell origin. Part 2 covers risk assessment and staging, findings that suggest the presence of aggressive tumors, recurrent/metastatic disease, and treatment with chemotherapy and external-beam radiotherapy. Experimental treatments utilizing molecular targets, redifferentiation agents, and gene therapy are covered briefly as well.
“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.
Editor’s Note: The statistical support was funded through an intramural faculty startup grant. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
Invited Critique: Thyroid Cancer Operations for Obese Patients
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.”
Thyroid Cancer More Aggressive in Younger Patients
Papillary thyroid carcinoma is more aggressive in younger patients, but this may not impact prognosis, researchers here concluded.
Patients 18 and younger have a more aggressive form of the disease than adults, reported Paolo Miccoli, M.D., and colleagues at the University of Pisa in Italy in the February issue of Otolaryngology - Head & Neck Surgery.
Dr. Miccoli and colleagues retrospectively analyzed data from 2,709 patients (622 males and 2,087 females, mean age 44.6) who had a total thyroidectomy for papillary thyroid carcinoma from 2000 through 2005. Neck dissections were performed when the researchers suspected the presence of metastatic nodes.
The researchers evaluated size and subtype of the greater tumor, and presence of thyroid capsule infiltration, node metastases, and an intact tumor capsule. The three subtypes most represented were Classic, Follicular, and Tall-Cells.
Patients with tumors larger than 1 centimeter in diameter received radioactive iodine therapy.
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.
Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
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