Extent of surgery for intermediate-risk well-differentiated thyroid cancer

Comparison of the abilities of staging and risk stratification systems to predict the long-term structural recurrence in patients with differentiated thyroid carcinoma after total thyroidectomy and radioactive iodine remnant ablation

Background

In patients with differentiated thyroid carcinoma (DTC), various staging and risk stratification systems have been applied to estimate long-term recurrence, which is a major issue during the postoperative follow-up period. However, the efficacy of these systems remains unclear in this context.

Methods

The present historical cohort study included 510 patients with DTC who underwent a total thyroidectomy followed by radioactive iodine (RAI) remnant ablation. Enrolled patients were categorized according to the 8^th edition of American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) Tumor Node Metastasis (TNM) staging system, the 2015 American Thyroid Association (ATA) initial risk stratification system, and the dynamic risk stratification (DRS) system. The ability of each system to predict long-term structural recurrence was compared using proportion of variance explained (PVE) by logistic regression models.

Results

The median follow-up period was 108 months. Structural recurrence occurred in 7.6% of the patients (n=39/510). Disease-free survival (DFS) curves of the patients within each category in the TNM staging system, the ATA initial risk stratification system, and the DRS system were significantly different (P<0.001). The PVE of the DRS system (20.7%) was higher than those of the TNM staging system and the ATA initial risk estimates.

Conclusions

The DRS system may effectively predict long-term structural recurrence and guide long-term management and follow-up strategies in patients with DTC undergoing total thyroidectomy and RAI remnant ablation.

Impact of the change from the seventh to eighth edition of the AJCC TNM classification of malignant tumours and comparison with the MACIS prognostic scoring system in non-medullary thyroid cancer

Background

In 2018, AJCC TNM staging changed for differentiated (DTC) and anaplastic (ATC) thyroid carcinoma. The impact of this change on mortality rates was investigated and compared with the MACIS prognostic score.

Methods

Analysis of a prospective database of DTC/ATC was undertaken. Patients were staged according to TNM7 and TNM8 criteria, and MACIS scores calculated. Five‐year disease‐specific mortality rates were determined. Proportions were compared with Fisher's exact and χ² goodness‐of‐fit tests.

Results

Between August 2002 and December 2016, 310 patients had primary surgery for thyroid cancer. After exclusions, 159 patients (154 DTC, 5 ATC) remained to be studied. The MACIS score was less than 6 in 105 patients (66·0 per cent), 6–6·99 in 19 (11·9 per cent), 7–7·99 in 14 (8·8 per cent) and 8 or more in 21 (13·2 per cent), with corresponding disease‐specific 5‐year mortality rates of 0, 5, 14 and 86 per cent. For TNM7 the distribution was stage I in 53·5 per cent (85 patients), stage II in 10·1 per cent (16), stage III in 14·5 per cent (23) and stage IV in 22·0 per cent (35), and differed from that for TNM8: 76·7 per cent (122), 10·7 per cent (17), 4·4 per cent (7) and 8·2 per cent (13) respectively (P < 0·001). Overall disease‐specific 5‐year mortality rates by stage for TNM7 versus TNM8 were: stage I, 0 of 85 versus 3 of 100 (P = 0·251); stage II, 0 of 16 versus 6 of 16 (P = 0·018); stage III, 3 of 23 versus 2 of 7 (P = 0·565); stage IV, 20 of 32 versus 11 of 11 (P = 0·020).

Conclusion

Compared with TNM7, TNM8 downstaged more patients to stage I and accurately reflected worse prognosis for stage IV disease. TNM8 is an inferior predictor of mortality compared with MACIS.

Total thyroidectomy versus lobectomy for intermediate-risk papillary thyroid carcinoma: A single-institution matched-pair analysis

BACKGROUND

Total thyroidectomy (TT) is recommended by guidelines for intermediate-risk papillary thyroid carcinoma (PTC) but its survival advantage over lobectomy has not been proven. The aim of this study was to examine the association between the extent of surgery and the clinical outcome of patients with intermediate-risk PTC.

METHODS

Adult patients with PTC in the institutional database from 1996 to 2008 were retrospectively reviewed. Intermediate-risk patients were defined according to the 2015 American Thyroid Association (ATA) guidelines. Patients who underwent TT and patients who underwent lobectomy were then matched according to individual risk factors. Survival analysis was performed within the two paired groups, focusing on recurrence-free survival (RFS) and disease-specific survival (DSS) rates.

RESULTS

Among 4230 PTC patients, 1087 intermediate-risk patients were included, in total 341 pairs were matched based on sex, age, primary size, clinical nodes (cN), extrathyroidal extension (ETE), pathological lateral neck metastasis (pN1b) and lymph node ratio (LNR). For these paired cases, with a median follow-up of 125 months (46-192), the lobectomy and TT groups were similar with respect to both 10-year RFS rate (77.4% vs 80.2%, log rank = 0.244, p = 0.622) and DSS rate (97.2% vs 98.4%, log rank = 0.351, p = 0.554). When excluding pairs of cases (62 pairs) who received radioiodine ablation (RAI), survival results were also similar in lobectomy and TT groups with respect to 10-year RFS rate (81.2% vs 83.1%, log rank = 0.63, p = 0.42) and DSS rate (97.3% vs 98.1%, log rank = 0.95, p = 0.33).

CONCLUSIONS

For intermediate-risk PTC, no advantages of TT over lobectomy were found with respect to RFS rate or DSS rate.

Dynamic risk stratification system in post-lobectomy low-risk and intermediate-risk papillary thyroid carcinoma patients

OBJECTIVE

The dynamic risk stratification (DRS) and its current definition of each response-to-therapy category in post-lobectomy papillary thyroid carcinoma (PTC) patients have not been well studied. This study aimed to validate the DRS system and to investigate useful thyroglobulin (Tg) or anti-Tg antibody (Ab)-related parameters in defining each response-to-therapy category.

DESIGN

Retrospective observational study.

PATIENTS

This historical cohort study included 619 patients with PTC treated by thyroid lobectomy.

MEASUREMENTS

All enrolled participants were stratified according to the American Thyroid Association (ATA) initial risk stratification system and DRS system, respectively. The association between these stratifications and structural recurrence was evaluated.

RESULTS

The median follow-up period was 103 months. Structural recurrence occurred in 1.6% of the patients with excellent response, 3.8% of those with indeterminate response, 2.9% of those with biochemical incomplete response, and all patients with structural incomplete response. Five (1.5%) of the low-risk patients and 14 (5.0%) of the intermediate-risk patients had structural recurrence. The disease-free survival curves showed significant differences according to the DRS (P < .001) and ATA initial risk stratification (P = .012), respectively. The proportion of variance explained the DRS system and ATA risk stratification system for structural recurrence was 32.4% and 29.4%, respectively. A thyroid-stimulating hormone (TSH) level >2.75 μU/mL at 1 year after the initial operation (P < .001) was the only valuable risk factor for structural recurrence identified in this study.

CONCLUSION

The long-term postoperative management of PTC patients treated with thyroid lobectomy could be guided based on the DRS.

The effects of the Union for International Cancer Control/American Joint Committee on Cancer Tumour, Node, Metastasis system version 8 on staging of differentiated thyroid cancer: a comparison to version 7

OBJECTIVE

To assess the changes resulting from the changes from UICC/AJCC TNM version 7 to version 8 and to subsequently determine whether TNM version 8 is an improvement compared to previous iterations of the TNM system and other staging systems for differentiated thyroid cancer (DTC) with regard to prognostic power.

DESIGN

Database study of DTC patients treated in our centre between 1978 up to and including 1 July 2014. Results were compared to our previous comparison of prognostic systems using the same data set.

PATIENTS

2257 DTC patients.

MEASUREMENTS

Staging in accordance with TNM 7 and TNM 8. Thyroid cancer-specific mortality; comparison was based on p-values of univariate Cox regression analyses as well as analysis of the proportion of variance explained (PVE).

RESULTS

There is a redistribution from stage 3 to lower stages affecting 206 (9.1%) patients. DTC-related mortality according to Kaplan-Meier for younger and older patients in TNM 7 had a slightly lower prognostic power than that in accordance with TNM 8 (P = 8.0 10^-16 and P = 1.5 10^-21 , respectively). Overall staging is lower in 627/2257 (27.8%) patients. PVE (TNM 7: 0.29; TNM 8: 0.28) and the P-value of Cox regressions (TNM 7: P = 7.1*10^-52 ; TNM 8: P = 3.9*10^-49 ) for TNM version 8 are marginally lower than that for TNM version 7, but still better than for any other DTC staging system.

CONCLUSION

TNM 8 results in a marked downstaging of patients compared to TNM 7. Although some changes, like the change in age boundary, appear to be associated with an improvement in prognostic power, the overall effect of the changes does not improve the predictive power compared to TNM 7.

The Trend of Age-Group Effect on Prognosis in Differentiated Thyroid Cancer

Age has been included in various prognostic scoring systems for differentiated thyroid cancer (DTC). The aim of this study is to re-examine the relationship between age and prognosis by using Surveillance, Epidemiology, and End Results (SEER) population-based database. We identified 51,061 DTC patients between 2004 and 2012. Patients were separated into 10-year age groups. Cancer cause-specific survival (CSS) and overall survival (OS) data were obtained. Kaplan-Meier and multivariable Cox models were built to analyze the outcomes and risk factors. Increasing age gradient with a 10-year interval was associated with the trend of higher proportions for male gender, grade III/IV and summary stage of distant metastases. Both CSS and OS continued to worsen with increasing age, being poorest in in the oldest age group (≥71); multivariate analysis confirmed that CSS continued to fall with each age decade, significantly starting at 60 years (HR = 7.5, 95% 1.0–54.1, p = 0.047) compared to the young group (≤20). Similarly, multivariate analysis suggested that OS continued worsening with increasing age, but starting at 40 years (HR = 3.7, 95% 1.4–10.1, p = 0.009) compared to the young group. The current study suggests that an age exceeding 60 years itself represents an unfavorable prognostic factor and high risk for cancer-specific death in DTC.

Comparing a thyroid prognostic nomogram to the existing staging systems for prediction risk of death from thyroid cancers

OBJECTIVE

Thyroid prognostic nomogram can be applied across different histological types for predicting the individualized risk of death from thyroid cancer. The objective of this study was to compare the strength of our recently published thyroid prognostic nomogram with 12 existing staging systems to predict the risk of death from thyroid cancer.

METHOD

This study included 1900 thyroid cancer patients, from a population based cohort of 2296 patients, on whom adequate staging information was available. Competing risk sub-hazard models were used to compare 12 pre-existing prognostic models with the nomogram model. Their relative strengths for prediction of patients' individualized risks of death from thyroid cancer were compared using Akaike information criterion (AIC), delta AIC, and concordance index. R version 3.2.2 was used to analyze the data.

RESULTS

Our cohort of 450 males and 1450 females included 1796 (93.4%) differentiated thyroid cancers. Amongst the compared models, thyroid prognostic nomogram model appeared to be better than other models for predicting the risk of death from all non-anaplastic thyroid cancer (concordance index = 94.4), differentiated thyroid cancer (concordance index = 94.1) and papillary thyroid cancer (concordance index = 94.7). The difference from next best staging systems was most pronounced in non-anaplastic thyroid cancer (delta AIC = 114.8), followed by differentiated thyroid cancer (delta AIC = 35.6) and papillary thyroid cancer (delta AIC = 8.4).

CONCLUSIONS

Thyroid prognostic nomogram model was found to be better than the other models compared for predicting risk of death from thyroid cancer.

The TNM system (version 7) is the most accurate staging system for the prediction of loss of life expectancy in differentiated thyroid cancer

OBJECTIVE

Many prognostic systems have been developed for differentiated thyroid cancer. It is unclear which one of these performs 'best'. Our aim was to compare staging systems applicable to our patient database to identify which best predicts DTC-related loss of life expectancy and DTC-specific mortality.

DESIGN

Database study of patients with DTC treated in our centre between 1978 (earliest available data) up to and including 1 July 2014. All were staged in accordance with the AMES, Clinical Class, Memorial Sloan Kettering, Ohio State University, TNM versions 5 and 6/7, University of Alabama, University of Münster and qTNM systems.

PATIENTS

A total of 2257 patients with differentiated thyroid cancer.

MEASUREMENTS

Loss of life expectancy expressed as relative survival and thyroid cancer-specific mortality. Comparison was based on P values of univariate Cox regression analyses as well as analysis of the proportion of variance explained (PVE).

RESULTS

Median available follow-up time was 7·2 years (range: 0-35·1 years). Three hundred and twenty-seven patients died, 149 of whom died of DTC. Version 7 of the TNM system was best for predicting DTC-related mortality (P = 7·1 × 10^-52 ; PVE = 0·296), followed by TNM version 5 (P = 6·7 × 10^-44 ; PVE = 0·255). For prediction of loss of life expectancy, version 7 of the TNM system was also best, closely followed by the Clinical Class system (P both < 2 × 10^-16 ).

CONCLUSIONS

The UICC/AJCC TNM system version 7 outperforms other prognostic classification systems based on extent of disease at the start of treatment both for prediction of differentiated thyroid cancer-related death and for prediction of loss life expectancy.

Identifying the most appropriate age threshold for TNM stage grouping of well-differentiated thyroid cancer

OBJECTIVE

Age is integrated in most risk stratification systems for well-differentiated thyroid cancer (WDTC). The most appropriate age threshold for stage grouping of WDTC is debatable. The objective of this study was to evaluate the best age threshold for stage grouping by comparing multivariable models designed to evaluate the independent impact of various prognostic factors, including age based stage grouping, on the disease specific survival (DSS) of our population-based cohort.

METHODS

Data from population-based thyroid cancer cohort of 2125 consecutive WDTC, diagnosed during 1970-2010, with a median follow-up of 11.5 years, was used to calculate DSS using the Kaplan Meier method. Multivariable analysis with Cox proportional hazard model was used to assess independent impact of different prognostic factors on DSS. The Akaike information criterion (AIC), a measure of statistical model fit, was used to identify the most appropriate age threshold model. Delta AIC, Akaike weight, and evidence ratios were calculated to compare the relative strength of different models.

RESULTS

The mean age of the patients was 47.3 years. DSS of the cohort was 95.6% and 92.8% at 10 and 20 years respectively. A threshold of 55 years, with the lowest AIC, was identified as the best model. Akaike weight indicated an 85% chance that this age threshold is the best among the compared models, and is 16.8 times more likely to be the best model as compared to a threshold of 45 years.

CONCLUSION

The age threshold of 55 years was found to be the best for TNM stage grouping.

Association of Pre-miR-146a rs2910164 Polymorphism with Papillary Thyroid Cancer

The incidence rate of papillary thyroid cancer (PTC) has increased over the past decades, but the pathogenesis remains unclear. rs2910164, located in pre-miR-146a, has been studied in PTCs with different ethnicity, but the results were inconsistent. Here we evaluate the association between rs2910164 polymorphism and PTC and investigate the effect of this polymorphism on patients' clinicopathological characteristics. 1238 PTC patients and 1275 controls, all Han population, from Northern China, were included in our study. rs2910164 was genotyped using Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS). Analysis of inheritance model was performed using the SNPStats program. Strength of association was assessed by odds ratio (OR) and 95% confidence interval (CI). Overall, no statistical difference in rs2910164 genotype distribution and allelic frequencies between cases and controls was found, and patients with different genotypes had similar clinicopathological characteristics in terms of stage, location, concurrent of benign thyroid tumor, and thyroiditis, while, as the number of G alleles increased, proportion of patients aged ≥45 years and those without metastasis increased (P trend < 0.001 and P trend = 0.003, resp.). However, no association remained significant after Bonferroni correction under any model of inheritance. Our results suggest no association between rs2910164 polymorphism with PTC and patients' clinicopathological characteristics.

A cross-specialty survey to assess the application of risk stratified surgery for differentiated thyroid cancer in the UK

INTRODUCTION

This study describes variability of treatment for differentiated thyroid cancer among thyroid surgeons, in the context of changing patterns of thyroid surgery in the UK.

METHODS

Hospital Episodes Statistics on thyroid operations between 1997 and 2012 were obtained for England. A survey comprising six scenarios of varying 'risk' was developed. Patient/tumour information was provided, with five risk stratified or non-risk stratified treatment options. The survey was distributed to UK surgical associations. Respondent demographics were categorised and responses analysed by assigned risk stratified preference.

RESULTS

From 1997 to 2012, the Hospital Episode Statistics data indicated there was a 55% increase in the annual number of thyroidectomies with a fivefold increase in otolaryngology procedures and a tripling of cancer operations. Of the surgical association members surveyed, 264 respondents reported a thyroid surgery practice. Management varied across and within the six scenarios, and was not related consistently to the level of risk. Associations were demonstrated between overall risk stratified preference and higher volume practice (>25 thyroidectomies per year) (p=0.011), fewer years of consultant practice (p=0.017) and multidisciplinary team participation (p=0.037). Logistic regression revealed fewer years of consultant practice (odds ratio [OR]: 0.96/year in practice, 95% confidence interval [CI]: 0.922-0.997, p=0.036) and caseload of >25/year (OR 1.92, 95% CI: 1.044-3.522, p=0.036) as independent predictors of risk stratified preference.

CONCLUSIONS

There is a substantial contribution to thyroid surgery in the UK by otolaryngology surgeons. Adjusting management according to established case-based risk stratification is not widely applied. Higher caseload was associated with a preference for management tailored to individual risk.

Update on differentiated thyroid cancer staging

In this review, we demonstrate how initial estimates of the risk of disease-specific mortality and recurrent/persistent disease should be used to guide initial treatment recommendations and early management decisions and to set appropriate patient expectations with regard to likely outcomes after initial therapy of thyroid cancer. The use of ongoing risk stratification to modify these initial risk estimates is also discussed. Novel response to therapy definitions are proposed that can be used for ongoing risk stratification in thyroid cancer patients treated with lobectomy or total thyroidectomy without radioactive iodine remnant ablation.

Validation of the QTNM staging system for cancer-specific survival in patients with differentiated thyroid cancer

An Australian state database was used to test the validity of the Quantitative tumor/node/metastasis (QTNM) staging system for assessing prognosis of differentiated thyroid cancer (DTC) on the basis of four variables quantified at diagnosis (histopathology, age, node involvement, and tumor size). Using the Queensland Cancer Registry (QCR), we identified 788 cases of DTC diagnosed from 1982 to 2006 with complete staging information. Causes of death were ascertained by linking the QCR database with the Australian National Death Index. Subjects were staged according to AJCC TNM 7th edition and QTNM, and cancer-specific survival (CSS) was calculated by the Kaplan-Meier method. Cancer-specific mortality was observed in 22 (2.8 %) patients, with 10-year CSS for the cohort of 97.0 % at a median follow-up of 262.8 months. QTNM stage specific cancer survival at 10 years was 99.6, 97.0, and 78.6 % for low-, intermediate-, and high-risk groups, respectively. This was comparable to the original US dataset in which the QTNM was initially studied, and it fared better at discriminating survival than the standard TNM system, where there was overlap in survival between stages. The current study validates the QTNM system in an Australian cohort and shows at least equivalent discriminatory capacity to the current TNM staging system. The QTNM utilized prognostic variables of significance to produce an optimal three-stage stratification scheme. Given, its advantage in clearly discriminating between prognostic groups, clinical relevance and simplicity of use, we recommend that TNM be replaced with QTNM for risk stratification for both recurrence and CSS.

The age factor in survival of a population cohort of well-differentiated thyroid cancer

Well-differentiated thyroid carcinoma (WDTC) represents a group of thyroid cancers with excellent prognosis. Age, a well-recognized risk factor for WDTC, has been consistently included in various prognostic scoring systems. An age threshold of 45 years is currently used by the American Joint Cancer Committee-TNM staging system for the risk stratification of patients. This study analyzes the relationship between the patients' age at diagnosis and thyroid cancer-specific survival in a population-based thyroid cancer cohort of 2115 consecutive patients with WDTC, diagnosed during 1970-2010, and evaluates the appropriateness of the currently used age threshold. Oncological outcomes of patients in terms of disease-specific survival (DSS) and disease-free survival (DFS) were calculated by the Kaplan-Meier method, while multivariable analysis was done by the Cox proportional hazard model and proportional hazards regression for sub-distribution of competing risks to assess the independent influence of various prognostic factors. The mean age of the patients was 47.3 years, 76.6% were female and 83.3% had papillary carcinoma. The median follow-up of the cohort was 122.4 months. The DSS and DFS were 95.4 and 92.8% at 10 years and 90.1 and 87.6% at 20 years, respectively. Multivariable analyses confirmed patient's age to be an independent risk factor adversely affecting the DSS but not the DFS. Distant metastasis, incomplete surgical resection, T3/T4 stages, Hürthle cell histology, and male gender were other independent prognostic determinants. The DSS was not independently influenced by age until the age of 55 years. An age threshold of 55 years is better than that of 45 years for risk stratification.

Comparison with published systems of a new staging system for papillary and follicular thyroid carcinoma

BACKGROUND

Several staging systems exist to estimate the prognosis for patients with thyroid carcinoma. Our goal was to develop a new staging system to predict cancer-specific survival (CSS) and evaluate it against published systems.

METHODS

The Cedars-Sinai Medical Center (CSMC)'s staging system was derived using data from an adjusted analysis of 1622 patients with differentiated thyroid carcinomas (DTCs) from the CSMC Thyroid Cancer Center. Mean follow-up time was 11.8 years. There were 1180 female and 442 male patients with a mean age of 46. Staging systems reviewed include University of Alabama (Birmingham) and M.D. Anderson Cancer Center (UAB-MDACC); the Tumor-Node-Metastasis (TNM) 5th and 7th editions; Memorial Sloan-Kettering (MSK); the National Thyroid Cancer Treatment Cooperative Study (NTCTCS); Ohio State; Clinical Class; Metastases, Age, Completeness of resection, Invasion, and tumor Size (MACIS); Noguchi; and the Yildirim model for predicting outcomes. The proportion of variance explained (PVE) and the C-index were computed to rank and compare each staging system's ability to predict CSS with this patient population.

RESULTS

Adjusted hazard ratios revealed that age at surgery of >45 years, the presence of distant metastases, capsular invasion, and vascular invasion were the most significant predictors of CSS in this patient population. The final CSMC risk score consists of low-, moderate-, and high-risk groups. Among the well-differentiated thyroid carcinoma staging systems, the CSMC and NTCTCS ranked highest with PVE values of 5% and 4.3%, respectively, while the NTCTCS and CSMC staging systems were reversed using the C-index (0.77 and 0.76, respectively).

CONCLUSION

The PVE and C-index values were relatively low across all applicable staging systems and varied in each study reviewed. This suggests that no one staging system has been shown to be superior to another across different patient populations with DTC. In the future, additional factors, such as biological markers, added to the clinical and pathological characteristics may lead to the development of superior staging systems.

Clinical prognostic index for recurrence of papillary thyroid carcinoma including intraoperative findings

This study created a new staging system using a risk model that employed clinical factors that were associated with recurrence, verified by preoperative clinical information and intraoperative finding and was compared with other staging systems. A review was conducted of patients who have undergone thyroidectomy and followed-up between January 1, 1983 and September 31, 2007 at Yonsei University Wonju Christian Hospital. The final prognostic staging system was defined as University of Yonsei clinical staging system (Prognostic score = 0.03 × Age + 0.8 × (if male gender) + 0.5 × (if extrathyroidal tumor extension present) + 0.7 × (if clinically apparent lymph node metastasis present), Stage I, less than 1.50; Stage II, 1.50 to 2.29; Stage III, 2.30 to 3.29; Stage IV 4, 3.3 or more). Compared with the other staging systems, the proportion of variation explained (PVE %) was calculated for each. The University of Yonsei clinical staging system appeared to be first as an accurate prognosis predictor with 11.9%. New staging system can predict recurrence and has advantage can use preoperative clinical information and intraoperative finding. Those who are diagnosed as high risk patients using the new staging system should be treated with aggressive surgical treatment and close follow-up.

Skip lateral neck node metastases in papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinomas (PTCs) are commonly associated with lymph node metastases (LNMs), which are thought to disseminate sequentially, first to the central compartment and later to the lateral compartment. However, a small number of patients have skip metastases to the lateral compartment without central LNMs. This study was performed to evaluate the clinicopathologic characteristics of skip metastases in PTC.

METHODS

We reviewed the medical records of 147 patients who underwent total thyroidectomy with central neck dissection plus modified radical neck dissection (RND) for PTC. A single surgeon performed all operations. The patients were classified as either present or absent skip metastases. The clinicopathologic characteristics were statistically analyzed.

RESULTS

Skip metastases were found in 32 patients (21.8%) and occurred commonly with primary tumors of the upper pole, and with tumors ≤1 cm in diameter. Skip metastases were less common in patients with multifocal disease. Patients with skip metastases had fewer metastatic lateral nodes that were more frequently found at a single level: mostly at level III (96.9%) and level II (34.4%).

CONCLUSIONS

Although skip metastases occur in only a small number of patients, the lateral compartment should be carefully evaluated for skip metastases, even though primary tumors are either single focus, located in the upper pole, or ≤1 cm in diameter.

Outcomes and prognostic factors of 251 patients with minimally invasive follicular thyroid carcinoma

BACKGROUND

Radioiodine ablation after total thyroidectomy is the generally accepted treatment for patients with widely invasive follicular thyroid carcinoma (FTC). The therapeutic strategy for minimally invasive FTC, on the other hand, is still a matter of controversy. The histological diagnosis of minimally invasive FTC is often made after lobectomy. The aim of this study was to determine the factors associated with the development of distant metastases in patients with minimally invasive FTC.

METHODS

Between 1989 and 2006, 251 patients with minimally invasive FTC underwent initial surgery at our hospital. Their median follow-up period was 7.2 years. There were 194 women and 57 men. Their mean age at the time of surgery was 46 years. Distant metastases were diagnosed in 54 patients (21.5%). In 22 of them distant metastases were diagnosed at the time of the initial surgery (M1), and in the other 32 they were diagnosed during the follow-up period. Age at initial surgery, sex, primary tumor size, histological findings (differentiation, and extent of vascular and capsular invasion), completion total thyroidectomy, and distant metastases at initial surgery were assessed as prognostic factors for distant-metastases-free survival (DMFS) and cause-specific survival (CSS). The Kaplan-Meier method and log-rank test were used to analyze time-dependent variables. The Cox proportional hazard model was used to perform the multivariate analysis.

RESULTS

Univariate analysis showed that age (45 years or older) and primary tumor size (4 cm or more) were significant prognostic factors related to postoperative distant metastases in the group of 229 patients without distant metastases at time of the initial surgery. The cumulative survival rate was significantly poorer in M1 patients, patients aged 45 years or older, and patients whose primary tumor size was 4 cm or more. Multivariate analysis showed that age was a significant prognostic factor both for DMFS and CSS.

CONCLUSIONS

Age was the most powerful prognostic factor for patients with minimally invasive follicular thyroid cancer. The prognoses of patients younger than 45 years old were excellent and distant metastases rarely occurred. Routine completion total thyroidectomy and radioiodine ablation is thought unnecessary for these patients.

Prognostic value of lymph node metastases of differentiated thyroid cancer (DTC) according to the local advancement and range of surgical excision

In differentiated thyroid carcinoma (DTC) with primary tumor smaller than 1 cm, the routine central lymph node (LN) dissection is questioned, due to increased risk of post-surgery complications and lack of confirmed benefit.

Aim

The analysis of prognostic significance of LN metastases, in DTC patients to verify the potential role of central neck lymphadenectomy on disease staging.

Materials and methods

The group of 195 DTC patients, primarily operated between 2004 and 2005, was retrospectively analyzed. 184 patients after radical operation, with no distant metastases diagnosed before surgery, were included into analysis. LN metastases were observed in 55 of cases (28%). In 124 cases only dissection of central LN compartment was performed, in 36 patients also uni- or bilateral modified cervical lymphadectomy was carried out. In 24 patients with tumor limited to the thyroid gland without suspicious lymph nodes, the routine central lymph node dissection was not done.

Results

Median follow-up was 4 years. The 5-year overall and disease free survival standardized ratio were 100% and 95% respectively. The risk of LN metastases increased with the more locally advanced cancer. In the group of 124 patients, in whom only central LN dissection was performed, LN metastases were diagnosed in 15 cases (12%). No significant relation between multifocality and frequency of central and/or lateral LN metastases was noticed. Significant correlation between N feature and extrathyroidal invasion was observed (p = 0,0003). The presence of LN metastases was related to worsening of disease free survival from 99 to 90%. During the follow-up recurrence occurred in 6 (3%) cases. In 24 patients in whom only total thyroidectomy was done, no local or distant recurrence was observed. The assessment of early postoperative complications (hypoparathyroidism, paresis of vocal cords) indicated that the frequency of early calcium balance disturbances was significantly lower in patients in whom central LN dissection was not performed (p = 0,04)

Conclusions

Our result indicate that in the early diagnosis of thyroid cancer, the occurrence of LN DTC metastases is rarer and was observed only in 12% of elective dissections of central LN node compartment, if no lateral dissection was indicated due to the lack of clinical suspicion. In DTC patients with tumor diameter <1 cm and no sonographical or inraoperative suspicion on LN involvement, routine central lymphadenectomy may be not obligatory.

Total thyroidectomy followed by postsurgical remnant ablation may improve cancer specific survival in differentiated thyroid carcinoma

PURPOSE

To determine the effect of the extent of thyroidectomy and additional postsurgical radioiodine remnant ablation (RRA) on the survival of patients with differentiated thyroid carcinoma (DTC) after adjustment for risk stage.

METHODS

We electronically identified 614 cases of DTC at our institution between 1987 and 2006. Two treatment variables were created, surgical extent dichotomized to total versus other and a composite of surgery and radioactive iodine ablation. The odds of cancer specific survival and disease-free survival (DFS) were determined using Cox proportional hazards model with adjustment for quantitative tumor-node-metastasis risk score.

RESULTS

Of 614 patients with DTC during our period, 504 (83%) underwent total thyroidectomy and 104 (17%) underwent lesser surgery. Radioiodine administration was reported for 394 patients who underwent total thyroidectomy with a dose range of 24 to 297 mCi (mean of 116 mCi). Ten-year survival was higher for patients with total thyroidectomy compared with lobectomy: 96% versus 84% (P<0.001, Gehan's Wilcoxon test). Ten-year survival for complete versus incomplete surgery for tumor stages 1 and 2 was 99% versus 96%, and for stages 3 and 4 was 88% versus 52%. Cancer specific death tended to occur earlier in those without RRA postsurgery. There was no overall relationship between DFS and RRA or surgery, but in the higher risk categories surgery retained significance.

CONCLUSION

Our data support the routine use of both total or near-total thyroidectomy followed by RRA over all risk categories in DTC. Although the effect of surgery is clear, there is also a trend toward improvement in outcome with RRA for cancer specific survival.

A comparison of prognostic classification systems for differentiated thyroid carcinoma

OBJECTIVE

To identify and compare prognostic classification systems based on basic tumour characteristics that were developed and/or validated for differentiated thyroid carcinoma (DTC).

DESIGN

Retrospective chart study.

METHODS

Literature was studied using PubMed. Fifteen different prognostic classification systems were identified, of which seven were developed or validated for DTC patients and were based on basic tumour characteristics. These systems were applied to 1225 DTC patients who were treated in our hospital between 1978 and 2002.

RESULTS

Log-rank analysis of Kaplan-Meier cancer-specific survival curves showed that the curve of the Tumor, Lymph-Node, Metastasis (TNM) system had the greatest discriminatory power (log-rank test, log P = -84.9). Cox-regression analysis showed that the TNM system was the most powerful determinant of cancer-specific survival curves. Proportion of variance explained (PVE) analysis showed that the TNM system had the highest PVE.

CONCLUSION

Of the prognostic classification systems analysed in this study, the TNM system performs best in all the three analyses, and is therefore the most suitable for predicting outcome in DTC-patients.

Simplifying the TNM System for Clinical Use in Differentiated Thyroid Cancer

Purpose

The TNM stratification has been found useful at stratifying patients with differentiated thyroid carcinoma (DTC) into prognostic risk groups. However, it is cumbersome to implement clinically given the large number of bins within this system and the complicated system of arriving at stage information.

Patients and Methods

We decided to quantify each variable in this system to arrive at a simplified quantitative alternative to the TNM system (QTNM) and compare this with the conventional system. We used our electronic record system to identify 614 cases of DTC managed at our institution from 1987 to 2006. Cancer-specific survival (CSS) and disease-free survival (DFS) were calculated by the Kaplan-Meier method, and a simplified QTNM score was devised using a Cox proportional hazards model.

Results

We were able to quantify the TNM system as follows: 4 points each for age older than 45 years and presence of neck nodal metastases while 6 points for tumor size larger than 4 cm or extrathyroidal extension and 1 point for nonpapillary DTC. A sum of 0 to 5 points was low risk, 6 to 10 points intermediate, and 11 to 15 points high risk. Comparison with the conventional TNM system and two other systems revealed similar or better discrimination with the QTNM and this discrimination was maintained when this risk stratification was applied to a unique validation set.

Conclusion

The QTNM system as opposed to the conventional TNM system seems to be a simple and effective method for risk stratification for both recurrence and cancer-specific mortality.

Staging systems for papillary thyroid carcinoma: a study of 2 tertiary referral centers

OBJECTIVE

To find out the most applicable and consistent staging system for papillary thyroid carcinoma (PTC) available in the literature.

BACKGROUND

The commonly used staging systems for PTC have predicted cancer-specific survival (CSS) well. However, their applicability and generalizability have not yet been evaluated in different clinical settings.

METHODS

A MEDLINE search from 1965 to 2005 was carried out to identify different staging systems available in the literature and 9 systems were applicable to 1634 PTC patients within 2 tertiary-referral centers. The CSS of each staging system within individual centers were calculated using Kaplan-Meier method and the CSS of each tumor stage in one individual center was compared with that of the other by log-rank test. In addition, within each center, the predictability of each staging system relative to the others was ranked based on the proportion of variation explained (PVE) value.

RESULTS

Clinicopathologic features, treatment received, and tumor stages were significantly different between the 2 centers. There were also significant differences in CSS within at least one tumor stage between the 2 centers in 8 of the 9 staging systems. The TNM was a highly predictive and consistent staging system within the 2 centers. Although the absolute PVE values differed between the 2 centers, the relative ranking of the 9 staging systems within each center correlated significantly to each other (P < 0.05).

CONCLUSIONS

Despite referral, treatment, and data collection biases inherent within each center, the TNM system remained to be the most applicable and consistent staging system for PTC in 2 centers managing the same population group.

Staging systems for papillary thyroid carcinoma: a review and comparison

OBJECTIVE

To find out the most predictive staging system for papillary thyroid carcinoma (PTC) currently available in the literature.

BACKGROUND

Various staging systems or risk group stratifications have been used extensively in the clinical management of patients with PTC, but the most predictive system for cancer-specific survival (CSS) based on distinct histologic types remains unclear.

METHODS

Through a comprehensive MEDLINE search from 1965 to 2005, a total of 17 staging systems were found in the literature and 14 systems were applied to the 589 PTC patients managed at our institution from 1961 to 2001. CSS were calculated by Kaplan-Meier method and were compared by log-rank test. Using Cox proportional hazards analysis, the relative importance of each staging system in determining CSS was calculated by the proportion of variation (PVE).

RESULTS

All 14 staging systems significantly predicted CSS (P < 0.001). The 3 highest ranked staging systems by PVE were the Metastases, Age, Completeness of Resection, Invasion, Size (MACIS) (18.7) followed by the new AJCC/UICC 6th edition tumor, node, metastases (TNM) (17.9), and the European Organization for Research and Treatment of Cancer (EORTC) (16.6).

CONCLUSIONS

All of the currently available staging systems predicted CSS well in patients with PTC regardless of which histologic type from which they were derived. When predictability was measured by PVE, the MACIS system was the most predictive staging system and so should be the staging system of choice for PTC in the future.

Prognostic Factors in Papillary and Follicular Thyroid Carcinoma: Their Implications for Cancer Staging

BACKGROUND

Papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) are two distinct histological types of thyroid carcinoma but have often been studied and staged as a collective group, known as differentiated thyroid carcinoma (DTC). However, this may not be an optimal approach to cancer staging.

METHODS

A total of 760 patients with DTC, comprising 589 (77.5%) with PTC and 171 with (22.5%) FTC, being managed at our institution from 1961 to 2001 were retrospectively reviewed. Their clinicopathological features, treatment modalities received, and postoperative outcome were analyzed. Both univariate and multivariate analyses were performed to identify prognostic factors related to cancer-specific survival (CSS) for PTC and FTC.

RESULTS

There were statistically significant differences between PTC and FTC in terms of age >/=50 years at diagnosis (P = .040), tumor size (P < .001), lymph node metastases (P < .001), distant metastases (P < .001), extrathyroidal extension (P < .001), multifocality (P = .002), capsular invasion (P < .001), extent of thyroid resection (P < .001), radioiodine ablation (P < .001), and external-beam irradiation (P = .003). Although PTC and FTC had similar 10-year and 15-year CSS (P = .846), each possessed its own set of independent prognostic factors for CSS. Age at diagnosis and completeness of resection were independent prognostic factors in both PTC and FTC.

CONCLUSIONS

There were marked differences in clinicopathologic features, treatment, and prognostic factors between the two histologic types of DTC. Different staging systems should be evaluated and validated for PTC and FTC individually in the future.

Overview of the management of differentiated thyroid cancer

Thyroid cancer is an uncommon tumor accounting for roughly 1% of all new malignancies. Differentiated (ie, papillary or follicular) thyroid carcinoma is usually asymptomatic, and frequently appears as a solitary thyroid nodule but few show cervical lymphadenopathy or metastasis to lung, bone, or liver. Fine needle aspiration (FNA) is recommended in the initial diagnostic test. Depending on the size of the lesion and other associated risk factors, most patients are treated with total or near total thyroidectomy. Postoperative radioiodine ablation is performed when tumor has a potential for recurrence. Recurrence rates and cancer-specific mortality is decreased by suppressing thyroid stimulating hormone (TSH). Long-term surveillance and follow-up with physical examination every 3 to 6 months for 2 years and then annually if patient remains cancer free. Whole body iodine scans are done every 12 months for follow-up until one negative scan (either withdrawal of thyroid hormone or rhodium complex -TSH). Thyroglobulin measurements (with antithyroglobulin antibodies) and ultrasound neck are suggested at 6 and 12 months and then annually if disease free.

Pre-ablative Diagnostic Whole-body Scan Following Total Thyroidectomy for Well-differentiated Thyroid Cancer: Is It Necessary?

OBJECTIVE

This study reviewed the incidence of positive pre-ablative diagnostic scan after total thyroidectomy and the efficacy of the current ablative dose. The predictive factors for outcome using a standard ablative dose and postoperative complications of total thyroidectomy were also examined.

METHODS

This was a retrospective review of patients referred for radioiodine ablation after total thyroidectomy between September 1997 and September 2001.

RESULTS

Forty patients were included in this study, of whom 95% had a positive scan after total thyroidectomy. Of the 30 patients who underwent standard 80-mCi radioiodine ablation, 21 (70%) had successful single ablation while the remaining nine patients needed a higher ablative dose. There were no significant differences between patients who had successful ablation with the standard dose and those who did not in terms of tumour size, patient age, lymph node status and extra-thyroidal extension. Fifteen percent suffered from permanent hypoparathyroidism requiring calcium supplementation. Three patients had documented recurrent laryngeal nerve paralysis.

CONCLUSION

Bypassing the pre-ablative diagnostic scan is feasible. The present ablation dose of 80 mCi of radioiodine is effective. The relatively high postoperative morbidity after difficult total thyroidectomy suggests less aggressive excision and postoperative radioiodine ablation of the remnant tissue.

Importance of tumour size in papillary and follicular thyroid cancer

BACKGROUND

The most controversial change in the new pathological tumour node metastasis (pTNM) classification of thyroid tumours is the extension of the pT1 classification to include tumours up to 20 mm.

METHODS

Four hundred and three patients with pT1 or pT2 differentiated thyroid carcinomas were divided into three groups according to tumour diameter (group 1, 10 mm or less; group 2, 11-20 mm; group 3, 21-40 mm). They were analysed retrospectively with respect to carcinoma-specific and disease-free survival.

RESULTS

No patient in group 1 died from papillary thyroid carcinoma, compared with three patients in group 2 and six in group 3. There was a statistically significant difference in carcinoma-specific survival between groups 1 and 2 (P = 0.033). Two patients in group 1, six in group 2 and eight in group 3 developed recurrence. The difference in disease-free survival between groups 1 and 2 was significant (P = 0.025). One patient in group 1, three in group 2 and four in group 3 died from follicular thyroid carcinoma, but there were no significant differences in survival between the three groups.

CONCLUSION

Extension of the pT1 classification to cover all tumours up to 20 mm does not appear to be justified for papillary thyroid carcinoma.

A model for predicting outcomes in patients with differentiated thyroid cancer and model performance in comparison with other classification systems

BACKGROUND

This study was performed to determine the prognostic factors for differentiated thyroid cancer, and to establish a mathematical prognostic model.

STUDY DESIGN

A retrospective study was conducted in 347 differentiated thyroid cancer patients. Univariate and multivariate prognostic factor analyses were carried out using the Kaplan-Meier and Cox regression methods.

RESULTS

Without adjustment for treatment in the multivariate analysis, age, tumor size, angioinvasion, and distant metastasis were significant predictors of outcomes. The very low-risk, low-risk, high-risk, and very high-risk groups were identified from the logistic regression equation. Overall and event-free survival estimations at 10 years were 100% and 100% for very low-risk patients, 88% and 75% for low-risk patients, 30% and 16% for high-risk patients, and 5% and 0% for very high-risk patients. Inclusion of treatment in the multivariate analysis showed, in addition to other variables, that both total or near total thyroidectomy (versus thyroidectomy less than total and near total thyroidectomy, p = 0.0002; hazard ratio, 0.4; 95% CI, 0.3-0.7) and adjuvant radioactive iodine treatment (versus no treatment with radioactive iodine, p = 0.0001; hazard ratio, 0.5; 95% CI, 0.2-0.8) were associated with a reduced hazard of death in the followup period. By subgroup analysis, total and near total thyroidectomy, along with radioactive iodine, appeared to provide a survival benefit for all patients except those in the very low-risk group.

CONCLUSIONS

The proposed mathematical model is satisfactory for predicting outcomes. Total and near total thyroidectomy along with radioactive iodine treatment might provide a survival advantage for differentiated thyroid cancer, except for those with very low risk.

Gasless Video-assisted Total Thyroidectomy in the Treatment of Low Risk Intrathyroid Papillary Carcinoma

Video-assisted thyroidectomy, although an increasingly used method to treat benign thyroid nodules, is rarely used to treat thyroid cancer. We performed gasless video-assisted total thyroidectomy for the treatment of papillary carcinoma of the thyroid. The patients were two men and five women with ages ranging from 29 to 52 years (median 35 years). Tumor size ranged from 0.7 to 3.8 cm (median 1.8 cm). The remnants of functional thyroid tissues were ablated with 1110 MBq of 131I following total thyroidectomy. One year after radioiodine ablation uptake of 74 MBq 131I shown by scintigraphy ranged from 0.29% to 0.70% (median 0.57%), and the serum thyroglobulin level was less than 1 microg/L. No perioperative complications occurred. The follow-up period ranged from 1 year 5 months to 3 years 7 months (median 2 years 10 months). In conclusion, gasless video-assisted total thyroidectomy is a feasible means for treating relatively small, non-invasive, clinically solitary, differentiated thyroid carcinomas.

Quality of life with well-differentiated thyroid cancer: treatment toxicities and their reduction

INTRODUCTION

Patients with well-differentiated thyroid cancer have a good prognosis but a significant chance for local recurrence. In the past, limited surgery with postoperative 131I only for extremely high-risk cases or recurrence was not uncommon. As more aggressive surgical and postoperative treatments appear to gain wider acceptance, toxicity and long-term morbidity become more important issues. Our goal is to present the experience of a single institution with emphasis on oral side effects related to 131I as well as acute and chronic symptoms related to this diagnosis and their impact on quality of life.

METHODS

Fifty-seven patients were followed for a median time of 19.3 months. All patients received therapeutic 131I (mean dose, 154.7 mCi) between January 1, 1996 and August 30, 2002.

RESULTS

Fifty-four patients (94.7%) were alive at the time of analysis. Sixteen (28.1%) required a second treatment: any sign of persistence resulted in retreatment. Complaints with 131I treatment included altered taste, 26.3%; acute xerostomia, 21.1%; and acute sialoadenitis, 15.8%. Chronic xerostomia occurred in 6 (35.3%) of all patients who received multiple treatments. The incidence of chronic xerostomia was reduced to 1 of 11 (9.1%) with amifostine pretreatment. Other chronic side effects associated with this disease included fatigue 54.4%, weight gain of more than 6 months duration 24.6%, with 12 (27.9%) of those under 60 experiencing an average gain of 2.3 kg from initial diagnosis.

CONCLUSION

Review of treatment-related symptoms prompted policies to reduce toxicity including amifostine pretreatment for 131I therapy and thyrotropin (synthetic TSH) use in place of iatrogenic hypothyroidism for thyroglobulin testing and scanning.

Enhancement of lymph node metastasis and distant metastasis of thyroid carcinoma

BACKGROUND

The mechanisms of local and distant metastases are imperfectly understood. The goal of the current study was to add to the body of knowledge regarding local and distant metastases of thyroid malignancies.

METHODS

The authors performed multivariate analysis of 573 patients who underwent surgery between November 1994 and May 2002 for follicular (FTC; n = 100), papillary (PTC; n = 236), or medullary thyroid carcinoma (MTC; n = 237) at a university hospital.

RESULTS

In multivariate analysis, extrathyroidal extension consistently evolved as the key risk factor for both lymph node metastasis and distant metastasis. This correlation was most pronounced in MTC and least pronounced in FTC. The risk of lymph node metastasis also increased with reoperative status in patients with MTC and with primary tumor diameter in patients with MTC (tumor diameter > 10 mm) and patients with PTC (tumor diameter > 20 mm). In the PTC group, lymph node metastasis was more common among patients younger than age 45. In the MTC group, extrathyroidal growth and distant metastasis were associated exclusively with lymph node metastasis. Lymph node metastasis was the only secondary risk factor for distant metastasis. In the analysis of risk factors for distant metastasis in the FTC and PTC groups, no interaction was found between extrathyroidal growth and lymph node metastasis. This finding suggests that extrathyroidal growth and lymph node metastasis of FTC and PTC, and presumably also MTC, represent separate mechanisms and routes of distant metastasis.

CONCLUSIONS

Screening for both local residual disease and distant metastases should be intensified in the high-risk population of patients whose primary tumors exhibit large diameters, extrathyroidal growth, or lymph node metastasis.

Postoperative Surveillance of Differentiated Thyroid Carcinoma: A Selective Approach

This review was conducted to evaluate the selective use of 131I whole-body scanning (WBS) and radioablation (RA) after thyroidectomy for patients with differentiated thyroid carcinoma (DTC). A review of patients undergoing thyroidectomy for DTC between July 1, 1980 and December 31, 1999 was performed. Postoperative surveillance involved a selective RA protocol based on a modification of the AMES criteria (age, metastases, extent of cancer, size, and multifocality of tumor). Lower-risk patients were followed by yearly thyroglobulin (Tg) levels and physical examinations (PE) whereas higher-risk patients additionally underwent WBS and RA when appropriate. Three hundred forty-three patients were identified; of these 27 per cent had positive lymph nodes or metastatic disease at their initial operation. Two hundred thirteen (64%) patients underwent postoperative WBS with 174 (82%) requiring RA. One hundred thirty (36%) low-risk patients were followed with yearly Tg and PE that when abnormal led to WBS and RA. No additional patient morbidity or mortality resulted from this protocol. Factors identified during multivariate analyses as being predictive of occult metastasis and recurrence ( P < 0.05) included tumor size and lymph node status. These data support a selective approach to the postoperative surveillance of DTC using Tg and PE to monitor low-risk patients and WBS for those with a higher risk of recurrence.

Application of staging systems for differentiated thyroid carcinoma in an endemic goiter region with iodine substitution

OBJECTIVE

To evaluate and compare staging systems for differentiated thyroid carcinoma and predicted outcome in an endemic goiter region with iodine substitution and to examine the risk profile of differentiated thyroid carcinoma and compare it against nongoiter regions.

SUMMARY BACKGROUND DATA

Differentiated (papillary or follicular) thyroid carcinoma has a favorable prognostic outcome. In numerous studies prognostic factors have been identified and staging systems created, particularly in Anglo-American centers (nonendemic goiter regions), to evaluate individual prognostic outcome.

METHODS

In a retrospective study, the authors assessed 440 patients with differentiated thyroid carcinoma (papillary, n = 293; follicular, n = 147) and a long-term follow-up of median 10.6 years to determine the predictive accuracy of nine staging systems applicable to the study population; the systems were compared by calculating the proportion of variation explained.

RESULTS

With regard to cause-specific mortality, the difference between the respective stages and/or risk groups was highly significant for every staging system. By means of calculating the proportion of variation explained, MACIS scoring supplied the most reliable prognostic information for differentiated thyroid carcinoma (relative importance 16.93%). EORTC and UICC/AJCC systems had a relative importance of 16.34% and 13.96%, respectively, also a high level of accuracy; this implies that they are superior to the other six staging systems. If we separate papillary and follicular carcinoma, for the former the MACIS score with a relative importance of 15.05% is clearly superior to the other staging systems, whereas for the latter the EORTC score and the UICC/AJCC staging system, with relative importance of 17.04% and 16.58%, respectively, yield the best prognostic information.

CONCLUSIONS

By applying staging systems in an endemic goiter region with iodine substitution, the best prognostic information for papillary thyroid carcinoma has been achieved with the MACIS score, while for follicular thyroid carcinoma the EORTC score and the UICC/AJCC system have the best prognostic accuracy. Because of the individual factors, which are easy to obtain and generally available (age, T, N, M classification), the uncomplicated handling, and the widespread use and the good predictive accuracy, the UICC/AJCC classification is the staging system of choice for comparing published results.

Papillary thyroid carcinoma: prognostic factors and the role of radioiodine and external radiotherapy

PURPOSE

To evaluate the role of radioiodine and external radiotherapy treatment in papillary thyroid carcinoma (PTC).

METHODS AND MATERIALS

This is a retrospective study of 842 patients with the diagnosis of PTC registered from 1960 to 1997 at the Department of Clinical Oncology, Queen Elizabeth Hospital, Hong Kong. The mean follow-up was 9.2 years. The stage distribution according to UICC/AJCC TNM staging was as follows: 58.6%, Stage I; 9.6%, Stage II; 26.1%, Stage III; 2.3%, Stage IV; and 3.4%, not stated.

RESULTS

The 10-year cause-specific survival (CSS) rates were as follows: Stage I, 99.8%; Stage II, 91.8%; Stage III, 77.4%; and Stage IV, 37.1%. Multivariate analysis showed that the statistically significant poor prognostic factors for CSS were as follows: age older than 45, postoperative gross locoregional (LR) residual disease, distant metastasis (DM) at presentation, and lack of radioactive iodine (RAI) treatment. In patients with no DM and no postoperative LR disease, adjuvant RAI ablation reduced both LR failure (RR [relative risk] = 0.29) and DM (RR = 0.2), although the CSS was not affected. In the subgroup of T1N0 M0 disease, no patient with RAI treatment had a relapse. External radiotherapy reduced the risk of LR failure to 0.35. Subgroup analysis revealed that external radiotherapy was particularly effective in increasing the probability of LR control of disease in patients with gross postoperative LR disease (RR = 0.36).

CONCLUSIONS

Both RAI and external radiotherapy were effective treatment in PTC. Total or near-total thyroidectomy followed by RAI treatment appears to result in the best outcome. External radiotherapy to improve LR control is indicated in patients with gross postoperative residual disease. Treatment should be individualized for patients with T1N0 M0 disease.