Endocrine Abstracts

Backgrounds: Preoperative diagnosis of parathyroid carcinoma (PC) is critical for the determination of the scope of surgical intervention. Nowadays, specific diagnostic markers for differentiation of PC and benign tumors are unknown, and less than half of patients with PC undergo necessary en bloc surgery.

Aims: To develop the instrument for preoperative diagnosis of PC.

Materials and methods: A multi-center retrospective study included 242 patients with primary hyperparathyroidism: 50 patients with PC, 30 with ?typical adenoma (AA), and 162 with adenoma of the parathyroid glands. We compared laboratory, instrumental and clinical characteristics. Comparison of two independent groups for quantitative data was performed using the Mann–Whitney test (U-test). Comparison of three independent groups for quantitative data was conducted using the Kruskal–Wallis ANOVA. The frequencies of binary variables were compared using the two-tailed Fisher exact test and Freeman–Halton test. The critical level of statistical significance for statistical hypotheses testing was taken as 0.05. CatBoosting algorithm was conducted to construct mathematical models for the differential diagnosis of PTG neoplasm types. Twelve factors were chosen by expert method for the model construction. At the first step, we reduced the dimension of feature space using sklearn. feature_selection, module ExtraTreesClassifier and SelectFromModel. Then we constructed the first model to differ PA and (PC or AA). At the second step, we also reduced feature space and constructed the second model to differentiate PC and AA.

Results: Patients with PC and AA had higher levels of PTH, ionized and albumin-corrected calcium, alkaline phosphatase, volume and the largest diameter of neoplasm, and the higher frequency of glomerular filtration rate decrease less than 60 ml/min per 1.73 m² compared to patients with adenoma. The frequency of low-energy fractures was higher in the carcinoma group versus the adenoma group (32% vs 8%). Heterogeneous structure and indefinite contour of glands detected by ultrasound were more typical for PC than for AA and adenomas. The mathematical model was developed using CatBoost gradient boosting algorithm for the noninvasive preoperative differential diagnosis of PC, AA, and adenoma.

Conclusions: Model can predict adenoma with PPV 100% and PC with PPV 81–92%. Using model clinicians could plan extended en bloc resection for PC and selective parathyroidectomy for adenoma. If AA is predicted, he has to make a decision on the choice of the necessary volume of parathyroidectomy based on his experience, because AA are the zone of uncertainty.