SUBCLINICAL CHARACTERISTICS AND FACTORS ASSOCIATED WITH PRIMARY CHEMOTHERAPY RESISTANCE IN GESTATIONAL TROPHOBLASTIC NEOPLASIA PATIENTS WITH FIGO SCORES OF 5–6 AT NATIONAL HOSPITAL OF OBSTETRICS AND GYNECOLOGY

Gestational trophoblastic neoplasia (GTN) is a group of malignancies characterized by vascular invasion and early metastasis but curable with timely diagnosis and appropriate treatment. Objective: To describe paraclinical characteristics and evaluate factors associated with primary chemoresistance in patients with FIGO score 5–6 GTN. Methods: A retrospective sectional study was conducted on 38 patients with FIGO score 5–6 GTN treated at the National Hospital of Obstetrics and Gynecology from January 2021 to December 2025. Results: Of 38 patients, 55.2% were aged 40 years or older, 65.8% resided in rural areas, mean BMI was 21.31 ± 1.66 kg/m², and 17 patients (44.7%) developed primary chemoresistance. Hydatidiform mole was the most common antecedent pregnancy (63.1%). Pre-treatment β-hCG levels were predominantly in the range of 10,000 to <100,000 IU/L; notably, all 5 patients with β-hCG < 1,000 IU/L were resistant to primary chemotherapy. The lung was the most common metastatic site (36.8%), detected on chest X-ray and chest computed tomography, but was not significantly associated with primary chemoresistance (OR = 0,556; p = 0,393). In an exploratory univariate analysis, three factors showed an association with primary chemoresistance: antecedent pregnancy interval exceeding 12 months (OR = 17.3; p = 0.013), pre-treatment β-hCG level, and invasive mole histology (OR = 0.037; p = 0.029). Conclusion: In patients with FIGO score 5–6 GTN, the lung is the most common metastatic site but was not significantly associated with primary chemoresistance. Low pre-treatment β-hCG does not necessarily indicate a favorable prognosis, because these cases often have a long latency period, in older patients with persistently very low levels of β-hCG, non-active disease causes of a positive hCG should be ruled out before concluding chemoresistance. Prolonged antecedent pregnancy interval and histopathology are important factors to consider when predicting treatment response.