UNFAVORABLE RESPONSES TO RADIOIODINE THERAPY IN N1B PAPILLARY THYROID CANCER: A PROPENSITY SCORE MATCHING STUDY

Prognostic factors for postoperative papillary thyroid cancer with unexplained elevated Tg: A retrospective study

Objective

This study aimed to investigate the underlying reasons for unexplained elevated thyroglobulin (Tg) in postoperative papillary thyroid cancer (PTC) patients according to follow-up results post RAT and to explore the long-term clinical outcomes and prognostic factors associated with these patients.

Methods

From April 2016 to June 2019, a retrospective study was conducted on postoperative PTC patients who underwent RAT at our institution. Patients with preablative stimulated thyroglobulin (psTg) > 10 ng/mL but no structurally evident disease were enrolled. The causal categorization for elevated Tg was analyzed 6 months post RAT and the long-term therapeutic responses were assessed at the end of follow-up. To identify risk factors influencing recurrence-free survival (RFS), both univariate and multivariate Cox regression analysis were employed. Kaplan-Meier method was utilized for plotting survival curves.

Results

A cohort of 165 subjects was enrolled for the analyses. Based on the results of a six-month follow-up, the postoperative unexplained elevated Tg among 165 patients could be ultimately attributed to thyroid remnant in 13.94% (23/165), biochemical disease in 60.00% (99/165), and structural disease in 26.06% (43/165). With a median follow-up of 58 months, 51 (30.91%), 34 (20.60%), 21 (12.73%), and 59 (35.76%) of the 165 patients achieved ER, IDR, BIR and SIR, respectively. Univariate analysis showed that N stage, TNM stage and suppressed Tg 6 months post RAT may be prognostic factors affecting RFS. Multivariate analysis showed that N1b stage [HR:2.749, P = 0.003] and II/III stage [HR:2.910, P = 0.001] were independent risk factors for RFS.

Conclusion

The proportion of 165 postoperative PTC patients with unexplained elevated Tg developing structural disease within nearly 5 years was over 30%. Patients with N1b stage and higher TNM stage were more likely to develop structural disease.

Current practice in intermediate risk differentiated thyroid cancer - a review

Although the overall prognosis for differentiated thyroid cancer (DTC) is excellent, a subset of patients will experience disease recurrence or may not respond to standard treatments. In recent years, DTC management has become more personalized in order to enhance treatment efficacy and avoid unnecessary interventions.In this context, major guidelines recommend post-surgery staging to assess the risk of disease persistence, recurrence, and mortality. Consequently, risk stratification becomes pivotal in determining the necessity of postoperative adjuvant therapy, which may include radioiodine therapy (RIT), the degree of TSH suppression, additional imaging studies, and the frequency of follow-up.However, the intermediate risk of recurrence is a highly heterogeneous category that encompasses various risk criteria, often combined, resulting in varying degrees of aggressiveness and a recurrence risk ranging from 5 to 20%. Furthermore, there is not enough long-term prognosis data for these patients. Unlike low- and high-risk DTC, the available literature is contradictory, and there is no consensus regarding adjuvant therapy.We aim to provide an overview of intermediate-risk differentiated thyroid cancer, focusing on criteria to consider when deciding on adjuvant therapy in the current context of personalized approach, including molecular analysis to enhance the accuracy of patient management.

Disease-free Survival of Patients with Differentiated Thyroid Cancer: A Study from a Tertiary Center in Oman

Objectives

As with global trends, the prevalence of differentiated thyroid cancer (DTC) has increased in recent years in Oman. However, to the best of our knowledge, no local studies have yet been published evaluating the prognosis of DTC cases in Oman. This study aimed to assess disease-free survival (DFS) and prognostic factors related to DTC among Omani patients attending a tertiary care center.

Methods

This retrospective, observational cohort study was conducted between January 2006 and May 2016 at the National Diabetes and Endocrine Center in Oman. Data related to DFS and prognostic factors were obtained from the electronic medical records of all ≥ 18-year-old patients diagnosed with DTC during the study period.

Results

A total of 346 DTC cases were identified. Overall, 82.7% of patients were disease-free at their last follow-up appointment. Univariate analysis indicated that various tumor characteristics including histological subtype (i.e., papillary carcinoma, Hurthle cell cancer, and minimally invasive follicular thyroid carcinoma), lymph node status, number of lymph node metastases, distant metastasis status, and TNM status (primary tumor (T), regional lymph node (N), distant metastasis (M) stage) were strong prognostic factors for DFS (p < 0.050). According to multivariate regression analysis, lymph node status, extrathyroidal extension, and angiovascular invasion were independent predictors of DFS (p < 0.050).

Conclusions

The overall prognosis of DTC among Omani patients was excellent. Treatment and follow-up strategies for patients with DTC should be tailored based on the individual’s risk factor profile.

Clinical Outcomes of N1b Papillary Thyroid Cancer Patients Treated with Two Different Doses of Radioiodine Ablation Therapy

BACKGROUND

The optimal dose of radioactive iodine (RAI) therapy for N1b papillary thyroid carcinoma (PTC) is controversial. We evaluated the clinical outcome of N1b PTC patients treated with either 100 or 150 mCi of RAI.

METHODS

We retrospectively analyzed N1b PTC patients who underwent total thyroidectomy and postoperative RAI therapy at a tertiary referral center between 2012 and 2017. As the baseline characteristics differed between treatment groups, we performed exact matching for various pathological factors according to RAI dose. We evaluated the response to therapy and recurrence-free survival (RFS) in the matched patients. Structural recurrent/persistent disease was defined as new structural disease detected after initial therapy, which was confirmed by cytology or pathology.

RESULTS

Of the total 436 patients, 37 (8.5%) received 100 mCi of RAI and 399 (91.5%) received 150 mCi of RAI. After an exact 1:3 matching, 34 patients in the 100 mCi group and 100 patients in the 150 mCi group remained. There was no significant difference in response to therapy between the groups in the matched population (P=0.63). An excellent response was achieved in 70.6% (n=24) of patients in the 100 mCi group and 76.0% (n=76) in the 150 mCi group. Two (5.9%) patients in the 100 mCi group and four (4.0%) in the 150 mCi group had recurrence and there was no significant difference in RFS between the groups in the matched population (P=0.351).

CONCLUSION

There were no differences in response to therapy and RFS in N1b PTC patients according to RAI dose.