Features of euthyroid disorder syndrome in cancer patients with different tumor localizations.

Abstract

e24093 Background: Euthyroid sick syndrome (ESS) is a complex of thyroid status changes associated with non-thyroidal pathology. However, the specific features of thyroid disorders depending on tumor location remain poorly understood. The aim of this study was to investigate the characteristics of thyroid status in primary cancer patients with different localizations of malignant tumors in the early stages of the disease (T1-2N0M0). Methods: The study included treatment-naive patients of both sexes, aged 45–59 years, with clinically and morphologically confirmed diagnoses: breast cancer (BC, n = 25), uterine cancer (UC, n = 25), lung cancer (LC, n = 28), renal cell cancer (RCС, n = 29), and cutaneous melanoma (СM, n = 25). Serum levels of thyroid-stimulating hormone (TSH), total and free thyroxine (T4), and total triiodothyronine (T3) were measured by radioimmunoassay (RIA). The control group comprised 42 healthy donors (mean age 53.5 ± 8.6 years). Statistical analysis was performed using parametric and nonparametric tests with appropriate adjustments for multiple comparisons. Results: A significant decrease in TSH levels (by 33%, p < 0.05) was observed only in patients with cutaneous melanoma (CM). Patients with other tumor types showed no significant differences in TSH compared to reference values. Total thyroxine (T4) levels increased by an average of 1.8-fold in all lung cancer (LC) patients and in 16% of breast cancer (BC) patients. In contrast, T4 levels were reduced by 1.4–1.7-fold in patients with renal cell cancer (RCC) and uterine cancer (UC). Total triiodothyronine (T3) concentration was decreased by 1.3–1.5-fold in RCC and CM patients but increased by 1.6-fold in patients with UC. Free T3 (FT3) levels were elevated by 1.3–1.8-fold in BC, LC, and CM patients but decreased by 1.5-fold in RCC patients. Free T4 (FT4) levels were reduced by 1.5-fold in RCC patients and increased by 1.4-fold in UC patients, with no significant changes observed in other groups. Conclusions: The development of malignant tumors at different sites leads to distinct patterns of euthyroid sick syndrome (ESS). A universal finding across all patient groups was a dissociation between total and free thyroid hormone fractions, suggesting a potential disruption in their peripheral metabolism. Notably, significant alterations in serum TSH levels were observed only in patients with cutaneous melanoma (CM); TSH remained within the reference range for all other tumor types. The identified ESS variants included a hyperthyroxinemic pattern in lung cancer (LC) and a subset of breast cancer (BC) cases, a hypothyroid-like pattern with a reduction in all hormone fractions in renal cell cancer (RCC), and a profile indicative of peripherally activated thyroid hormone metabolism in uterine cancer (UC).