Endocrine Abstracts

Introduction: An increased Body Mass Index (BMI) has been associated with higher prevalence of many cancers, including differentiated thyroid cancer. However, no data have been reported about potential impact of BMI on aggressiveness of presentation and clinical outcome of medullary thyroid cancer (MTC).

Aim: To evaluate the potential influence of BMI on clinical presentation and outcome of MTC.

Methods: We reviewed anthropometric and clinical data of 444 consecutive patients with sporadic MTC, surgically treated at the Endocrine Surgery Unit and followed at the Endocrine Unit of the University Hospital of Pisa, from 2000 to 2019.

Results: At time of surgery, 92/444 (20.7%) patients had BMI ≧ 30×kg/m² (Ob-group) and 352/444 (79.3%) < 30 kg/m² (control group). Ob-group patients were significantly older (median 59.5 vs 54.0 years, P=0.001), whilemale gender prevalence did not differ (44.6% vs 45.1%, P>0.4). Ob-group showed a significantly smaller tumor dimension compared with control group (median 1 cm vs 1.3 cm, P=0.001). Particularly, micro-MTC (≤ 1 cm)was present in 50/92 (54.3%) and 136/352 (38.6%), 1–2.5 cm tumors in 25/92 (27.2%) and 137/352 (38.9%), 2.5–4 cm tumors in 16/92 (17.4%) and 52/352 (14.8%) and tumors > 4 cm in 1/92 (1.1%) and 27/352 (7.7%), in Ob-group and control group, respectively (P=0.006). MTCs of Ob-group had both significantly lower T and N stage compared with control group (P=0.019 and 0.013, respectively). Otherwise, minimal extra-thyroid extension and multifocality did not differ (P>0.4). Ob-group patients had significantly lower levels of pre-operative calcitonin compared with control group (median 67.2 vs 123.5 pg/ml, P=0.036). After surgery, the follow-up time did not differ between Ob-group and controls (5.2 vs 6.3 years, P>0.1). At the end of follow-up, Ob-group showed significantly lower rate of structural disease, compared with control group (12/92, 13%, vs 80/352, 22.7%, P=0.036).

Conclusions: At the time of surgical treatment, about 21% of all sporadic MTC patients were suffering from obesity. In our series, patients with obesity had smaller tumors and less metastatic lymph node involvement, probably due to more frequent and careful medical evaluations experienced by these population leading to an early detection of MTC. Moreover, Ob-group had less structural disease at the end of the follow-up confirming the importance of an early diagnosis of MTC.