Correlation between obesity and clinicopathological factors in patients with papillary thyroid cancer

Purpose Epidemiological studies have shown that obesity is associated with an increased risk of thyroid cancer. However, the exact nature of the relationship, especially with respect to the behavior of the cancer, remains uncertain. The objective of this study was to evaluate the correlation between the body mass index (BMI) and clinicopathological features of thyroid cancer patients. Methods From January 2009 to April 2010, 716 consecutive patients (602 females and 114 males; mean age 47.02 +/- 11.73 years) with papillary thyroid cancer (PTC) were analyzed retrospectively. Patients were divided into two subgroups according to age (<45 years, >= 45 years). The BMI groupings were based on standardized categories set by the World Health Organization. The relationships between the BMI and these parameters were assessed. Results A non-overweight BMI was associated with a younger age and female gender. Tumor multiplicity was related to a higher BMI. In an age-related subgroup analysis, a higher BMI was correlated with more lymph node involvement (p = 0.004), lymphatic invasion (p = 0.003) and tumor multiplicity (p = 0.008) in patients >= 45 years of age. The absence of an association between the BMI and T stage, nodal status, vascular invasion, lymphatic invasion, and extrathyroidal extension was noted in a statistical analysis. In the subgroup of patients <45 years of age, no positive associations were observed between the BMI and any parameters other than age and sex. Conclusions In PTC patients >= 45 years of age, a higher BMI was associated with more aggressive tumor features, such as lymph node metastasis, lymphatic invasion, and tumor multiplicity.