Intermediate-risk Differentiated Thyroid Cancer Research Articles

Tracking dynamic evolution of low- and intermediate-risk differentiated thyroid cancer. identification of individuals at risk of recurrence

Tracking dynamic evolution of low- and intermediate-risk differentiated thyroid cancer. identification of individuals at risk of recurrence

Data-driven thyroglobulin cutoffs for low- and intermediate-risk differentiated thyroid cancer follow-up in a real-world setting

Data-driven thyroglobulin cutoffs for low- and intermediate-risk differentiated thyroid cancer follow-up in a real-world setting

Sufficiency of a Single Negative Thyroglobulin Standard for Judging the Success of Ablation in Low- and Intermediate-risk Differentiated Thyroid Cancer: A Retrospective Study.

We investigated how reduced successful ablation criteria may be used to evaluate radioiodine remnant ablation in patients with low- and intermediate-differentiated thyroid carcinoma (DTC). Overall, 254 low- and intermediate-risk patients with DTC were categorized into three groups (positive, weak, positive, and negative) on the basis of a visual study of thyroid imaging performed before postoperative iodine treatment. Semi-quantitative analysis parameters were incorporated into the positive Tc-99m pertechnetate scanning to further examine the clinical use of thyroid imaging. We investigated the value of successful judgment criteria and the influencing factors of radioiodine ablation. At the same time, the predictive value of thyroglobulin (Tg) for radioiodine treatment and the overall clinical efficacy were assessed. A total of 250 (98.43%) patients were identified as having functional thyroid tissue residue on the Tx-whole-body scan, and 137 (53.94%) patients had positive Tc-99m pertechnetate scans using semi-quantitative analysis. The single Tg standard could not substitute the double standard (χ! !=22.042, p<0.001) for patients with residual thyroid weight by a semiquantitative analysis. However, the semi-quantitative analysis revealed no association between 99mTcO4-thyroid scan and ablation treatment using semi-quantitative analysis; only preablation sTg levels were related with success in the multivariate logistic regression analysis, with a cut-off value of 2.88 ng/mL. The pre-ablation stimulated Tg level was also the primary factor of satisfactory response following follow-up with an optimal cut-off of 6.506 ng/mL. Even in low- and intermediate-risk patients with DTC, a single negative Tg standard also requires receiving some restrictions in the evaluation of ablation success and is inadequate. Conventional 99mTcO4 thyroid imaging combined with a quantitative analysis program can improve the clinical practice of single negative Tg standard.

Tracking dynamic evolution of low- and intermediate-risk differentiated thyroid cancer: Identification of individuals at risk of recurrence.

The generally good prognosis of low- and intermediate-risk differentiated thyroid cancer (DTC) underscored the need to identify those few patients who relapse. Records of 299 low- or intermediate-risk DTC patients (mean follow-up 8.2 ± 6.2 years) were retrospectively reviewed. The sample was classified following the American Thyroid Association (ATA) dynamic risk stratification (DRS) system. After classifying patients according to DRS at the first visit following initial therapy (FU1), structural recurrence occurred in 2/181 (1.1%), 5/81 (6.2%) and 13/26 (50.0%) with excellent, indeterminate and biochemical incomplete response to treatment, respectively. All relapses but one happened within 5 years from FU1. Univariate analysis comparing excellent, indeterminate and biochemical incomplete with structural incomplete responses at the end of the follow-up, identified tumour size (p < .001), T status (<0.001), positive lymph nodes (N) (p < .01), multifocality (p < .004), need of additional radioactive iodine (RAI) (p < .0001) and first DRS status (p < .0003) as risk factors of recurrence. In the multivariate analysis, only RAI remained statistically significant (p < .02). Comparison between excellent and indeterminate with biochemical and structural incomplete responses, identified tumour size (p < .0004), T (p < .01), N (p < .0001), bilaterality (p < .03), first DRS status (p < .0001) and RAI (p < .001) as recurrence risk factors. T (p < .01) and first DRS (p < .0006) were confirmed in the multivariate analysis. Patients with DTC classified as low- or intermediate-risk of recurrence with excellent response to treatment at FU1 rarely develop structural disease and this occurs almost exclusively in the first 5 years. Initial DRS status is an accurate tool for determining the risk of recurrence.

Ablation Rates and Long-Term Outcome Following Low-Dose Radioiodine for Differentiated Thyroid Cancer in the West of Scotland: A Retrospective Analysis

ObjectiveLow-dose radioiodine is an accepted means of remnant ablation in patients with low- to intermediate-risk differentiated thyroid cancer (DTC) based on the results of several phase III trials. We evaluated the rate of ablation success and long-term recurrence outcomes in the first 3 years of implementing this practice at our institution. MethodsPatients who received 1.1 to 1.2 gigabecquerel (30 millicurie) were identified retrospectively from the radionuclide database, January 1, 2012, to December 31, 2014, inclusive. Successful ablation was defined as Iodine-131uptake <0.1% on diagnostic scan and Tg level <2.0 ng/mL at 6 to 8 months after treatment. Follow-up was conducted annually for 10 years and relapse rates were determined based on the available clinical, radiological, and biochemical information. ResultsWe identified 114 patients, 109 of whom had dual response assessment. The median age was 43 years (range, 14 to 80 years). Almost 70% had T1 or T2 tumors, with T3 and T4 tumors recorded in 27% and 2.5% of patients, respectively. Nodal staging was performed in just over 30% and involved lymph nodes were detected in 21% (N1a 8% and N1b 13%). Ablation success based on diagnostic scan alone was 94.7% (108/114), Tg alone 94.7% (108/114), and on both modalities was 90.4% (103/114). ConclusionRemnant ablation was achieved in >90%, and the corresponding clinical recurrence rate was only 1.8% despite the inclusion of patients with locally advanced disease. Low-dose radioiodine is effective and may be suitable for a proportion of patients with higher-risk DTC.

Development of a predictive nomogram for intermediate-risk differentiated thyroid cancer patients after fixed 3.7GBq (100mCi) radioiodine remnant ablation.

The objective of this study was to develop a predictive nomogram for intermediate-risk differentiated thyroid cancer (DTC) patients after fixed 3.7GBq (100mCi) radioiodine remnant ablation (RRA). Data from 265 patients who underwent total thyroidectomy with central lymph node dissection (CND) and received RRA treatment at a single institution between January 2018 and March 2023 were analyzed. Patients with certain exclusion criteria were excluded. Univariate and multivariate logistic regression analyses were performed to identify risk factors for a non-excellent response (non-ER) to RRA. A nomogram was developed based on the risk factors, and its performance was validated using the Bootstrap method with 1,000 resamplings. A web-based dynamic calculator was developed for convenient application of the nomogram. The study included 265 patients with intermediate-risk DTC. Significant differences were found between the ER group and the non-ER group in terms of CLNM>5, Hashimoto's thyroiditis, sTg level, TgAb level (P < 0.05). CLNM>5 and sTg level were identified as independent risk factors for non-ER in multivariate analysis. The nomogram showed high accuracy, with an area under the curve (AUC) of 0.833 (95% CI = 0.770-0.895). The nomogram's predicted probabilities aligned closely with actual clinical outcomes. This study developed a predictive nomogram for intermediate-risk DTC patients after fixed 3.7GBq (100mCi) RRA. The nomogram incorporates CLNM>5 and sTg levels as risk factors for a non-ER response to RRA. The nomogram and web-based calculator can assist in treatment decision-making and improve the precision of prognosis information. Further research and validation are needed.

Impact factors of benefiting from initial 131 I ablation in patients with intermediate-risk differentiated thyroid carcinoma: a study based on a re-evaluation of therapeutic response.

This study was carried out to confirm whether patients with intermediate-risk differentiated thyroid cancer (DTC) could benefit from initial 131 I ablation and to identify the factors that impacted the benefit. We retrospectively assessed a cohort of 548 patients with intermediate-risk DTC who were classified into structural incomplete response (SIR), biochemical incomplete response (BIR), indeterminate response (IDR), and excellent response (ER) groups according to the ATA guidelines (version 2015). A downgrade in the classification, such as from initial SIR to final BIR, IDR, or ER, from BIR to IDR or ER, and from initial IDR to final ER, was defined as benefiting from initial 131 I ablation (benefit group). Non-downgraded classification meant non-benefit. 64.78% of patients benefited from the initial 131 I ablation in the final re-evaluation. Gender (OR = 0.038, P = 0.002), interval time (OR = 0.038, P = 0.002) and serum ps-Tg (OR = 0.961, P = 0.001) were independent prognostic factors for benefiting from initial 131 I ablation, with the cutoff value were 5 months and 19.08 ng/ml. Patients with intermediate-risk DTC could benefit from initial 131 I ablation. Female patients with intermediate-risk DTC whose interval time <5 months and ps-Tg <19.08 ng/ml were more likely to benefit. Early 131 I ablation for such patients is beneficial for achieving a complete therapeutic response.

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.

Assessment of three different radioiodine doses for ablation therapy of thyroid remnants: Efficiency, complications and patient comfort.

I-131 radioiodine (RAI) ablation removes postoperative residual tissue and facilitates follow-up in low- and intermediate-risk differentiated thyroid cancer (DTC). Although low doses have been reported to be as effective as higher doses for ablation, the doses administered still vary depending on the patient and the practitioner. We aimed to evaluate the ablation efficiency, complications, and length of stay (LOS) of patients with DTC treated with 3 different doses for ablation. Patients with DTC who received RAI therapy were retrospectively reviewed. One hundred thirty patients with low-intermediate-risk, according to American Thyroid Association classification, without known lymph nodes or distant metastases were included. Patients were divided into 3 groups as 30 to 50 mCi, 75 mCi, and 100 mCi. Residue thyroid and salivary glands were evaluated from 9 to 12 months post-RAI I-131 scans. No significant difference was found between groups regarding ablation success (P = .795). In multivariable analyses, pretreatment thyroglobulin (hazard ratio = 0.8, 95% confidence interval 0.601-0.952, P = .017) and anti- thyroglobulin antibody (hazard ratio = 1.0, 95% confidence interval 0.967-0.998, P = .024) were 2 independent predictors of ablation success. The mean LOS was 2.1 ± 0.3, 2.6 ± 0.6, and 2.9 ± 0.4 days, respectively, (P = .001). LOS rates of ≥ 3 days were 13.2%, 54.3%, and 84.8%, respectively. Mild decreases in hemoglobin, white blood cell (WBC), and platelet counts were observed in all groups after 6 weeks without any clinically significant findings. A lower rate of change in WBC counts was observed in the 30 to 50 mCi group compared to others. There was no dose-dependent difference regarding the early complaints questioned. Ablation with 30 to 50 mCi provides benefits such as shorter LOS, better patient comfort, less salivary gland dysfunction, and less WBC suppression, thus reducing costs without decreasing efficacy.

The effects of reoperations due to inadequate treatment in differentiated thyroid cancers on morbidity, mortality and costs

Although the incidence of differentiated thyroid cancer (DTC) is high, mortality is quite low. In low and intermediate risk DTCs, reoperations due to inadequate treatment can increase morbidity, mortality, and costs in patients. In our study, current articles published on this subject were reviewed and evaluated. According to our results, morbidity, mortality and costs increase due to inadequate treatment in DTCs. Therefore, even in low and intermediate risk DTC cases, adequate surgeries such as total or near total thyroidectomy should be performed by high volume endocrine surgeons and moderate TSH suppression should be applied in all cases.

BRAF-AXL-PD-L1 Signaling Axis as a Possible Biological Marker for RAI Treatment in the Thyroid Cancer ATA Intermediate Risk Category.

The use of radioiodine therapy (RIT) is debated in intermediate-risk differentiated thyroid cancer (DTC) patients. The understanding of the molecular mechanisms involved in the pathogenesis of DTC can be useful to refine patient selection for RIT. We analyzed the mutational status of BRAF, RAS, TERT, PIK3 and RET, and the expression of PD-L1 (as a CPS score), the NIS and AXL genes and the tumor-infiltrating lymphocytes (TIL, as the CD4/CD8 ratio), in the tumor tissue in a cohort of forty-six ATA intermediate-risk patients, homogeneously treated with surgery and RIT. We found a significant correlation between BRAF mutations and a less than excellent (LER, according to 2015 ATA classification) response to RIT treatment (p = 0.001), higher expression of the AXL gene (p = 0.007), lower expression of NIS (p = 0.045) and higher expression of PD-L1 (p = 0.004). Moreover, the LER patient group had a significantly higher level of AXL (p = 0.0003), a lower level of NIS (p = 0.0004) and a higher PD-L1 level (p = 0.0001) in comparison to patients having an excellent response to RIT. We also found a significant direct correlation between the AXL level and PD-L1 expression (p < 0.0001) and a significant inverse correlation between AXL and NIS expression and TILs (p = 0.0009 and p = 0.028, respectively). These data suggest that BRAF mutations and AXL expression are involved in LER among DTC patients and in the higher expression of PD-L1 and CD8, becoming new possible biomarkers to personalize RIT in the ATA intermediate-risk group, as well as the use of higher radioiodine activity or other possible therapies.

Patient Preference in Physician Decision-Making for Patients With Low- to Intermediate-Risk Differentiated Thyroid Cancer

This survey study describes the association between patient preference and physician decision-making in thyroid cancer.

Intermediate-risk Differentiated Thyroid Cancer with Stimulated Thyroglobulin or N1b Needs High Adjuvant Radioactive Iodine Dose

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Post-Surgical Indications to Radioiodine Treatment and Potential Risk Factors for Post-Treatment Recurrence in Patients with Intermediate-Risk Differentiated Thyroid Carcinoma.

In this multicentric retrospective observational study, we investigated the potential risk factors for radioiodine (RAI) indication and the post-treatment recurrence of intermediate-risk differentiated thyroid cancer (DTC) 1 and 3 years from diagnosis. We included 121 patients who underwent thyroidectomy for intermediate-risk DTC. The 92 patients (76.0%) who underwent RAI treatment had a higher prevalence of extra-thyroid micro-extension (mETE) (p = 0.03), pT3 staging (p = 0.03) and recourse to therapeutic central (p = 0.04) and lateral (p = 0.01) neck dissection, as well as higher numbers (p = 0.02) and greater dimensions (p = 0.01) of lymph node metastases, compared with untreated patients. Relapse was observed in 18.1% and 20.7% of cases 1 and 3 years from diagnosis, respectively, with no significant differences between groups. A lower age at diagnosis (p = 0.03) and higher levels of stimulated thyroglobulin (Tg) (p = 0.04) emerged as the only independent risk factors for tumour relapse at 1 year. Tumour relapse at 3 years was only independently predicted by the presence of tumour relapse at 1 year (p = 0.04). In conclusion, mETE, pT3 and the presence of large, multiple or clinically evident lymph node metastases represent the main indicators for referring patients to RAI treatment. Early recurrence may be considered the most relevant factor when planning further surveillance.

Thyroglobulin Value Predict Iodine-123 Imaging Result in Differentiated Thyroid Cancer Patients.

Background: In differentiated thyroid cancer (DTC) patients, the response to initial treatments is evaluated 6-12 months after radioiodine therapy (RIT) according to the 2015 American Thyroid Association (2015 ATA) criteria. In selected patients, diagnostic 131-radioiodine whole-body scintigraphy (Dx-WBS) is recommended. We evaluated the diagnostic performance of 123I-Dx-WBS-SPECT/CT imaging in detecting incomplete structural responses in the early follow-up of DTC patients and, additionally, derived optimized basal-Tg value as a yardstick for scintigraphic imaging. Methods: We reviewed the records of 124 low or intermediate-risk DTC patients with negative anti-thyroglobulin antibody. All patients had undergone (near)-total-thyroidectomy followed by RIT. The response to initial treatments was evaluated 6-12 months after RIT. Results: According to the 2015 ATA criteria, 87, 19 and 18 DTC patients were classified to have excellent response (ER), indeterminate/incomplete biochemical response (BIndR/BIR) or structural incomplete response (SIR), respectively. Among patients with less than ER, 18 had a positive 123I-Dx-WBS-SPECT/CT. Metastatic disease at 123I-Dx-WBS-SPECT/CT mainly involved lymph nodes within the central compartment, and corresponding neck ultrasound examinations were negative. The ROC curve analysis was performed to define the best basal-Tg cut-off (i.e., 0.39 ng/mL; AUC = 0.852) able to discriminate patients with and without positive 123I-Dx-WBS-SPECT/CT, respectively. The overall sensitivity, specificity, accuracy, PPV and NPV were 77.8%, 89.6%, 87.9%, 56.0% and 95.9%, respectively. Basal-Tg cut-off was an independent risk factor for having a positive 123I-Dx-WBS-SPECT/CT. Conclusion:123I-Dx-WBS-SPECT/CT identified lymph node metastases in 14/37 patients with less than ER and a negative neck ultrasound, thus modifying the management of such patients. The diagnostic performance of 123I-Dx-WBS-SPECT/CT significantly increased in patients with basal-Tg values ≥ 0.39 ng/mL.

Radioiodine (131I) treatment decision-making for low- and intermediate-risk differentiated thyroid cancer.

The purpose of this study was to investigate the effect and influencing factors of postsurgical radioactive iodine (RAI) therapy for patients with low- and intermediate-risk differentiated thyroid cancer (DTC). A retrospective analysis of 423 low- and intermediaterisk DTC patients admitted to the Department of Nuclear Medicine, Sichuan Provincial People's Hospital from January 2005 to December 2020 was performed. All patients were treated with surgery, had a postoperative pathological diagnosis, and were treated with RAI, including 89 males and 334 females. Recurrence risk stratification: 143 cases were low-risk, and 280 cases were intermediaterisk. The excellent response (ER) rate for low- and intermediate-risk were 93.7% and 78.2%, respectively (P < 0.05). There were significant differences in age, cumulative dose of [131I], and pretreatment stimulated-Tg (pre-Tg) levels between the low- and intermediate-risk groups (P < 0.05). There were significant differences in the cumulative dose of 131I and pre-Tg levels between ER and the non-ER group (P < 0.05). The area under the curve (AUC) values were 0.799 in the low-risk group, and 0.747 in the intermediate-risk group for the ROC curve by ER status of pre-Tg. The ER rate with RAI treatment decreased with an increase in pre-Tg levels. Pre-Tg was an important factor for RAI treatment decision-making and prognostic evaluation and differed between low-risk and intermediate-risk DTC. Aggressive RAI therapy was recommended for low-risk DTC with pre-Tg ≥ 20.0 ng/mL and in intermediate-risk group with pre-Tg ≥ 10.0 ng/mL.

A comparative analysis of treatment efficacy in intermediate-risk thyroid cancer.

This study aimed to evaluate the efficacy of different treatment combinations on patient survival in intermediate-risk differentiated thyroid cancer (DTC). The 2004-2017 National Cancer Database was queried for intermediate-risk papillary (PTC), follicular (FTC), or Hurthle cell (HTC) thyroid cancer patients. Four treatments were analyzed using Kaplan Meier and multivariable Cox regression: surgery, surgery with adjuvant radioiodine ablation (S + RAI), surgery with adjuvant thyroid-stimulating hormone suppression therapy (S + THST), and S + RAI + THST. Kaplan-Meier and multivariable Cox proportional-hazards analyses evaluated treatment-associated overall survival (OS). Of 65,736 patients, 72.2% were female and the average age was 45.4 ± 15.4years. The 10-year OS rates for PTC, FTC, and HTC were 93.2%, 85.2%, and 78.5%, respectively. S + RAI + THST exhibited higher OS than surgery alone and S + RAI (all p < 0.05). Compared to surgery alone, S + RAI + THST demonstrated reduced mortality in PTC (Hazard Ratio [HR]: 0.628, p < 0.001), FTC (HR: 0.490, p < 0.001), and HTC (HR: 0.520, p = 0.006). Similarly, adjuvant RAI + THST reduced mortality regardless of lymphovascular invasion (HR: 0.490, p < 0.001), N1a (HR: 0.570, p < 0.001) or N1b metastasis (HR: 0.621, p < 0.001), or positive margin status (HR: 0.572, p < 0.001). Treatment combinations demonstrated varying efficacies in intermediate-risk DTC depending on histology and tumor characteristics, with S + RAI + THST exhibiting the greatest treatment response.

Early Dynamic Risk Stratification Decreases Rate of Ablative and Adjuvant Radioiodine Use in ATA Low and Intermediate Risk Papillary Thyroid Cancer Patients.

In differentiated thyroid cancer (DTC), radioiodine (RAI) therapy is most frequently employed for remnant ablation or as adjuvant therapy for the remaining disease. The application of RAI to patients classified as intermediate risk (InR) is still a matter of debate. The aim of this study is to analyze the effect of early postoperative risk assessment on RAI use on papillary thyroid cancer patients who are classified as low risk (LoR) or InR. This is a single-center, prospective registry study. One-hundred-eighty-six patients operated between January 2012 and August 2021 and categorized as LoR or InR were included in this study. All patients had total thyroidectomy and central lymph node dissection by the same endocrine surgeon. An early dynamic risk assessment (EDRA) consisting of neck ultrasonography, serum thyroglobulin (Tg) and anti-Tg levels was performed 6 weeks after surgery. Most of the patients were either followed up without RAI or received ablative low activity (30-50 mCi) RAI based on predetermined criteria. Median follow-up was 63 months. Sixty-six (61%) patients in the LoR group and 43 (56%) patients in the InR group did not receive RAI treatment. Thirty-eight (35%) and 22 (29%) patients in LoR and InR groups received ablative (30-50 mCi) RAI therapy, respectively. In LoR group 5 (4.6%) patients and in InR group 12 (16%) patients received 100 mCi or more RAI activity. Only one patient in the InR group recurred during follow-up. No statistically significant difference regarding local recurrence was found between patients who didn't receive RAI or were treated with RAI within both LoR (p=0.152) and InR (p=0.272) groups. There is consensus for LoR patients about omitting RAI therapy after surgery. Indications for RAI treatment in InR DTC are still under debate. RAI use based on EDRA seems to be a better option than decisions solely made on histopathological risk factors and decreases adjuvant high-activity RAI use without increasing recurrence risk.

Is a four-week hormone suspension necessary for thyroid remnant ablation in low and intermediate risk patients? A pilot study with quality-of-life assessment

Radioiodine therapy (RIT) is a complementary treatment to total thyroidectomy in differentiated thyroid cancer (DTC) patients. High levels of thyroid-stimulating hormone (TSH) are usually required in clinical practice to increase RIT efficacy. Suspension of levothyroxine hormone for weeks is usually necessary, greatly impacting patients' quality of life. Patients with DTC of low or intermediate-risk were divided into two groups - one where levothyroxine was suspended for 4-5 weeks and a TSH ≥ 30 mUI/L was required for radioiodine administration (group 1), and another where levothyroxine was suspended for two weeks only (group 2). The RIT efficacy was compared between the groups. The absorbed dose in the cervical region after 24 hours was also calculated and correlated with TSH. The quality of life was also accessed with the EORTC questionnaire. Thirty-one patients were included in this study (14 in group 1 and 17 in group 2), with a mean age of 45.7 ± 10.6 years and 29 (93.5%) females. The mean TSH level for group 1 was 67.0 ± 35.6 UI/ml, and for group 2 was 31.3 ± 29.4 UI/ml. After six months, the successful RIT frequency was 66.6% for group 1 and 73.3% for group 2. Patients from group 2 showed better quality of life. TSH level ≥ 30 mUI/L is not critical for the success of RIT in patients with low or intermediate risk DTC. A two-week suspension of thyroid hormone appears to meet similar RIT needs, providing a better quality of life.

The prognostic value of post thyroidectomy Tc-99m pertechnetate thyroid scan in patients with differentiated thyroid cancer.

To evaluate the prognostic value of postoperative Tc-99m pertechnetate scanning in patients with differentiated thyroid cancer (DTC). Patients with pathologically proven low or intermediate-risk DTC were enrolled in this study. Postoperative Tc-99m pertechnetate scintigraphy was performed 20 min after IV of 185 MBq of Tc-99m pertechnetate Positive thyroid residual uptake was characterized as higher Tc-99m pertechnetate uptake at the thyroid bed than the surrounding background's activity. A negative residual was considered if there was no definite abnormal radioactivity at the thyroid bed. Follow-up by thyroglobulin, thyroglobulin antibodies (Tg Abs), neck ultrasound (US) and diagnostic I-131 WBS (Dx WBS) were considered the reference standard. Successful ablation outcome was considered if there was free Dx WBS, stimulated serum thyroglobulin < 1 ng/ml with negative Tg Abs, and free US. Two hundred and two patients, mean age; of 38.8 years were retrospectively recruited in this study. Positive residual uptake at the thyroid scan was detected in 131 patients wherea the remaining 71 patients had no detectable uptake. According to the reference standard we encountered 114 and 88 cases with successful ablation and unsuccessful ablation respectively, Tc-99m pertechnetate scanning successfully detected 63 true positive and 46 true negative cases giving 72% sensitivity, 40% specificity, 48% positive predictive value and 56% negative predictive value. In low- and intermediate-risk DTC patients; despite the relatively high sensitivity of postoperative Tc-99m pertechnetate thyroid scan, it has low specificity and low negative predictive value so it cannot be used to predict the ablation outcome.