# The value analysis of tumor deposit in the comprehensive evaluation before differentiated thyroid cancer RAI therapy

## TL;DR

This study shows that tumor deposits in thyroid cancer patients affect RAI therapy outcomes and should be considered in staging and risk assessment.

## Contribution

The study proposes integrating tumor deposits into the TNM staging and ATA risk stratification system for improved postoperative evaluation.

## Key findings

- Tumor deposits are an independent prognostic factor for RAI therapy outcomes in differentiated thyroid cancer.
- TD-positive patients in N1a stage have similar prognosis to TD-negative N1b patients.
- Incorporating TD into staging systems could improve risk stratification accuracy.

## Abstract

This study aimed to investigate the impact of tumor deposit (TD) on Radioiodine (RAI) therapy efficacy in Differentiated Thyroid Cancer (DTC) and explore their potential role in postoperative staging and the American Thyroid Association (ATA) initial risk stratification system before RAI treatment.

This study retrospectively analyzed data from a total of 11,278 thyroid cancer surgical patients between 2019 and 2023. Among 2,162 patients were considered eligible for prognostic analysis (2056 cases in the TD-negative group, 106 cases in the TD-positive group). A 1:1 propensity score matching was conducted for the TD-positive group. Single-factor and multiple-factor analyses of prognostic factors were performed for both groups. The predictive abilities of different N stages, TNM staging, and the ATA initial risk stratification system including TD were evaluated.

There were 235 cases (2.08%) of TD-positive patients. Multivariate analysis demonstrated that gender, presence of TD, the ATA initial risk stratification system, and TNM staging were independent prognostic factors. In all patients, those in the N1a stage, TNM stage I, and ATA intermediate risk group, the cumulative incidence of ER in the TD-positive group was lower than that in the TD-negative group (48.6% vs. 77.8%, 37.5% vs. 78.7%, 35.4% vs. 67.4%; P = 0.019, 0.001, 0.013 respectively). Patients with TD-positive in N1a stage had no significant difference in prognosis compared to TD-negative patients in N1b stage (32.6% vs. 42.6%, P = 0.867); TD-positive patients in TNM stage I had similar prognosis to TD-negative patients in TNM stage II (37.5% vs. 28.9%, P = 0.338); TD-positive patients in the ATA intermediate risk group showed no significant difference in prognosis compared to TD-negative patients in the ATA high risk group (35.4% vs. 12.5%, P = 0.300).

TD should be considered as a prognostic factor in the postoperative RAI treatment. We propose incorporating TD into the TNM staging and the ATA initial risk stratification system as a reference, suggesting that TD-positive patients in N1a stage be classified as N1b stage; patients in TNM stage I be classified as TNM stage II ;and the ATA intermediate risk patients be classified as the ATA high risk.