Portrait of the Inflammatory Response to Radioiodine Therapy in Female Patients with Differentiated Thyroid Cancer with/without Type 2 Diabetes Mellitus.

No clinical studies have investigated the effect of radioiodine ( 131 I)-targeted therapy on the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) as inflammatory response markers in patients with differentiated thyroid cancer (DTC) associated with type 2 diabetes mellitus (T2DM) and obesity. This study aimed to assess the relationship between blood radioactivity, body mass index (BMI), and peripheral blood cells three days after 131 I intake in 56 female patients without T2DM (DTC/-T2DM) vs. 24 female patients with T2DM (DTC/+T2DM). Blood radioactivity, measured three days after 131 I intake, was significantly lower in the DTC/+T2DM than in the DTC/-T2DM patients (0.7 mCi vs. 1.5 mCi, p < 0.001). The relationship between blood radioactivity and BMI (r = 0.83, p < 0.001), blood radioactivity and NLR (r = 0.53, p = 0.008), and BMI and NLR (r = 0.58, p = 0.003) indicates a possible connection between the bloodstream 131 I uptake and T2DM-specific chronic inflammation. In patients without T2DM, 131 I therapy has immunosuppressive effects, leading to increased NLR (19.6%, p = 0.009) and PLR (39.1%, p = 0.002). On the contrary, in the chronic inflammation context of T2DM, 131 I therapy amplifies immune metabolism, leading to a drop in NLR (10%, p = 0.032) and PLR (13.4%, p = 0.021). Our results show that, in DTC/+T2DM, the bidirectional crosstalk between neutrophils and obesity may limit 131 I uptake in the bloodstream. Considering the immune response to 131 I therapy, the two groups of patients can be seen as a synchronous portrait of two sides. The explanation could lie in the different radiosensitivity of T and B lymphocytes, with T lymphocytes being predominant in patients with DTC/-T2DM and, most likely, B lymphocytes being predominant in T2DM.