To analyze the influencing factors of short-term efficacy of ¹²⁵I seed implantation for recurrent cervical metastatic lymph nodes of esophageal squamous cell carcinoma after external beam radiation therapy (RESCC).

From January 2013 to March 2019, 47 patients (42 males, 5 females; age: 47-77 years) with RESCC who underwent CT guided ¹²⁵I seed implantation in Hebei General Hospital were retrospectively analyzed. Patients were divided into effective group (complete remission (CR)+ partial remission (PR)) and ineffective group (stable disease (SD)+ progressive disease (PD)) according to response evaluation criteria in solid tumors (RECIST) at 3 months after implantation. Multivariate logistic regression was used to analyze the independent influencing factors of short-term efficacy. Cut-off values were determined by ROC curve.

Of 47 patients, 26 were effective (3 were CR and 23 were PR) and 21 were ineffective (7 were SD, 14 were PD). Multivariate regression analysis showed that tumor diameter, immediate postoperative dose delivered to 90% gross tumor volume (D₉₀), recurrence interval time were independent influencing factors of short-term efficacy (odds ratio (OR; 95% CI): 4.240(1.220-14.737), 0.999(0.999-1.000), 0.989(0.979-1.000), Wald values: 5.163, 5.043, 3.956, all P<0.05). ROC curve showed that the AUC of tumor diameter, D₉₀ and recurrence interval time were 0.782, 0.786 and 0.838 respectively, with cut-off values of 4.85 cm, 115.78 Gy and 297.5 d respectively.

The short-term efficacy of ¹²⁵I seed implantation for RESCC is mainly related to the tumor diameter, immediate postoperative D₉₀ and recurrence interval time. Patients with tumor diameter <4.85 cm, immediate postoperative D₉₀>115.78 Gy and recurrence interval time >297.5 d have better efficacy.

Esophageal neoplasms; Carcinoma, squamous cell; Neoplasm metastasis; Lymph nodes; Neoplasm recurrence, local; Brachytherapy; Iodine radioisotopes; Treatment outcome