Differentiated thyroid cancer: radioiodine following lobectomy — a clinical feasibility study

Diagnosis and Treatment of Acute Pleural Effusion following Radioiodine Remnant Ablation Post Lobectomy for Thyroid Cancer

Radioiodine remnant ablation (RRA) was previously demonstrated to be a safe and effective alternative to completion thyroidectomy for patients with differentiated thyroid cancer (DTC). However, its side effects have not been fully investigated, particularly in patients with lobectomy. We reported a young euthyroidal female who underwent RRA post lobectomy and lymph node dissection for papillary thyroid cancer, whose post-ablation ¹³¹I-whole-body scan accidentally showed diffuse radioiodine distribution on chest-mimicking pulmonary metastases. Immediately-added single-photon emission computed tomography/computed tomography (SPECT/CT), nevertheless, revealed a ¹³¹I-accumulating swollen left thyroid lobe and emerging pleural effusion, which relieved after short-term treatment with prednisone. In summary, acute pleural effusion ascribed to RRA-induced thoracic duct compression was reported for the first time. ¹³¹I-lobectomy-induced pleural effusion could be precisely diagnosed by SPECT/CT and efficiently manipulated via treating radiation thyroiditis with the short-term administration of corticosteroid.

Propensity Score Matched Outcome Analysis of Lobar Ablation Versus Completion Thyroidectomy in Low-Risk Differentiated Thyroid Cancer Patients: Median Follow-Up of 11 Years

Background: Radioactive iodine lobar ablation (RAILA) of the contralateral thyroid lobe has been suggested as an alternative to completion thyroidectomy in patients of differentiated thyroid cancer (DTC) who underwent initial hemithyroidectomy. However, data on long-term outcomes are scarce. In this study, we intended to describe the long-term outcomes of RAILA versus completion thyroidectomy in a cohort of low-risk DTC patients. Methods: Data of patients with low-risk DTC who underwent initial hemithyroidectomy, and were subsequently treated with either completion thyroidectomy or RAILA between 1996 and 2015, were collected and analyzed. The treatment outcomes included ablation rate, recurrence rate, recurrence-free survival (RFS), and adverse events, and were validated by propensity score matching analysis. Results: Of the 1243 patients (median age: 34 years, range: 5-78) with low-risk DTC, 514 patients underwent upfront RAILA while 729 patients underwent completion thyroidectomy followed by remnant ablation. The ablation rate following the first radioactive iodine (¹³¹I) cycle was 75.3% [95% confidence interval (CI) 71.3-78.9] in the RAILA group versus 84.1% [CI 81.2-86.6] in the completion thyroidectomy group (p < 0.001). Over median follow-up of 11.4 years (interquartile range: 8.3-15.8), the recurrence rates between the two groups were not significantly different (1.6% [CI 0.7-3.2] vs. 1.0% [CI 0.4-2.1], respectively, p = 0.343). The product limit estimate of RFS at 10 years was 98.6% [CI 97.6-99.6%] in the RAILA group versus 99.1% [CI 98.3-99.9%] in the completion thyroidectomy group (p = 0.391). The outcomes in 497 matched pairs generated through propensity score analysis were similar. None of the patients in the RAILA group experienced permanent hypocalcemia or recurrent laryngeal nerve palsy, while the corresponding rates in the completion thyroidectomy group were 10/729 (1.4%) (p = 0.006) and 5/729 (0.7%) (p = 0.080), respectively. Radiation thyroiditis was seen in 25/514 (4.9%) patients in the RAILA group versus 3/729 (0.4%) in the completion thyroidectomy group (p < 0.001). Conclusions: Upfront RAILA is seen to be a noninvasive, safe, and effective alternative to surgical completion thyroidectomy in low-risk DTC patients in the absence of macroscopic malignancy in the remaining thyroid lobe.

131I Ablation of an Entire Thyroid Gland in Locally Invasive Differentiated Thyroid Cancer Without Surgery

ABSTRACT

A 79-year-old man with locally metastatic papillary thyroid cancer to left-sided cervical lymph nodes was referred for radioiodine therapy. He was considered unfit for thyroidectomy due to extensive local involvement and severe interstitial lung disease requiring continuous oxygen. The patient was treated with low doses of radioiodine (approximately 30 mCi) every 6 months with corticosteroid cover for 3 years with good effect. Sequential 131I scanning and serum thyroglobulin levels confirmed virtual complete ablation of the thyroid gland. The patient remained well on thyroid hormone replacement.

Radioiodine Ablation of Remaining Thyroid Lobe in Patients with Differentiated Thyroid Cancer Treated by Lobectomy: A Systematic Review and Metaanalysis

We aimed to conduct a systematic review and metaanalysis of studies reporting the performance of radioactive iodine (¹³¹I) therapy in differentiated thyroid cancer (DTC) patients requiring a completion treatment after lobectomy. We also evaluated the response to ¹³¹I therapy according to 2015 American Thyroid Association guidelines and the adverse events. Methods: A specific search strategy was designed to find articles evaluating the use of ¹³¹I in patients with evidence of DTC after lobectomy. PubMed, Cochrane Central Register of Controlled Trials, Scopus, and Web of Science were searched. The search was updated until January 2020, without language restriction. Data were cross-checked and any discrepancy discussed. A proportion metaanalysis (with 95% confidence interval) was performed using the random-effects model. Metaregressions on ¹³¹I success were attempted. Results: The pooled success ablation rate was 69%, with better results in patients receiving a single administration of about 3.7 GBq; high heterogeneity was found (I² test, 85%), and publication bias was absent (Egger test, P = 0.57). Incomplete structural responses were recorded in only 14 of 695 (2%) patients enrolled in our analysis. Incomplete biochemical responses were observed in 8%-24% of patients, with higher rates (24%) in patients receiving low radioiodine activities (∼1.1 GBq) and lower rates (8%-18%) in patients receiving higher activities of radioiodine (∼3.7 GBq). Neck pain due to thyroiditis was reported in up to 18% of patients, but in most cases, symptoms resolved after oral paracetamol or a short course of prednisone. Conclusion: Lobar ablation with ¹³¹I is effective, especially when high ¹³¹I activities are used. However, the rate of incomplete biochemical response to initial treatment appears to be slightly higher than in the classic scheme of initial treatment of DTC. Radioisotopic lobectomy should be considered for patients with low- to intermediate-risk DTC requiring completion treatment after lobectomy due to specific individual risk factors or patient preferences.

The role of radioactive iodine in the management of patients with differentiated thyroid cancer - An oncologic surgical perspective

With improved understanding of the biology of differentiated thyroid carcinoma its management is evolving. The approach to surgery for the primary tumour and elective nodal surgery is moving from a "one-size-fits-all" recommendation to a more personalised approach based on risk group stratification. With this selective approach to initial surgery, the indications for adjuvant radioactive iodine (RAI) therapy are also changing. This selective approach to adjuvant therapy requires understanding by the entire treatment team of the rationale for RAI, the potential for benefit, the limitations of the evidence, and the potential for side-effects. This review considers the evidence base for the benefits of using RAI in the primary and recurrent setting as well as the side-effects and risks from RAI treatment. By considering the pros and cons of adjuvant therapy we present an oncologic surgical perspective on selection of treatment for patients, both following pre-operative diagnostic biopsy and in the setting of a post-operative diagnosis of malignancy.

Thyroid lobe ablation with radioactive iodine as an alternative to completion thyroidectomy after hemithyroidectomy in patients with follicular thyroid carcinoma: long-term follow-up

BACKGROUND

Radioactive iodine lobe ablation (RAI-L-ABL) is a possible alternative to completion thyroidectomy (C-Tx) for follicular thyroid carcinoma (FTC), but no long-term outcome data are available after lobe ablation. We analyzed the long-term outcome of lobe ablation in a series of patients with FTC.

METHODS

This was a retrospective study of patients who were treated with lobe ablation between 1983 and 2008. Of 134 patients with FTC, 37 (27.6%) had lobe ablation with (131)I (30-32 mCi) (RAI-L-ABL), 68 (50.7%) had C-Tx, and 29 (21.6%) had initial total thyroidectomy (T-Tx). The main outcomes analyzed were (131)I uptake after lobe ablation, C-Tx or T-Tx, serum thyroglobulin (Tg), serum thyroid-stimulating hormone (TSH), long-term disease-specific mortality, and disease-free survival.

RESULTS

After lobe ablation, radioiodine uptake was significantly lower for the RAI-L-ABL group (0.6%) than for the C-Tx group (2.0%, p<0.005) or T-Tx group (1.3%, p=0.054). Subsequent remnant ablation was performed in 12 of 37 (32%) patients in the RAI-L-ABL group, in 58 of 68 (85.3%) patients in the C-Tx group, and in 25 of 29 (86.2%) patients in the T-Tx group (p<0.01). With median follow-up of 95 months for the RAI-L-ABL group, 47 months for the C-Tx group, and 53 months for the T-Tx group, there was one death in the RAI-L-ABL group and one death in the T-Tx group. No other RAI-L-ABL patients had detectable disease, whereas patients in the C-Tx group and two patients in the T-Tx group had detectable disease (p=0.18). Long-term stimulated or suppressed Tg of <1 ng/mL were found in 87.5% of the RAI-L-ABL group (n=28), 86.3% of the C-Tx group (n=57), and 77.8% of the T-Tx group (n=21). Tg was detectable in 40.6% of the RAI-L-ABL group compared to 13.8% of C-Tx and 28.6% of T-Tx groups (p<0.05, between groups).

CONCLUSIONS

RAI-L-ABL, C-Tx, and T-Tx are equally effective in achieving serum TSH concentrations of >25 mIU/L and preparing patients for conventional (131)I treatment and whole body scanning with similar long-term outcomes. However, persistent measurable Tg (range 0.2-2.2 ng/mL) is more common after RAI-L-ABL.

Clinical significance of residual occult malignancy in thyroid carcinoma

PURPOSE

Total or near-total thyroidectomy is advocated in reducing the recurrence rate and improving survival in differentiated thyroid carcinoma. However, this potential benefit could be seen in all patient groups or only in the patients who have multifocal disease. We analyzed the clinical significance of occult multifocal disease in patients with completion thyroidectomy.

PATIENTS AND METHODS

Ninety-seven patients in whom the completion thyroidectomy was performed within 6 months were included. The patients were grouped according to whether they have malignancy in the remnant thyroid tissue. The groups were examined and compared according to patients and tumor characteristics. The effect of the presence of residual tumor in remnant thyroid tissue on clinical course, disease-free survival, and overall survival were evaluated as well.

RESULTS

After completion thyroidectomy, 20 (20.6%) of the 97 patients revealed additional cancer focus in the residual tissue. Median follow-up period was 104 months (range, 84-205 months). Only tumor multifocality in the resected lobe after first surgery was predictive of the presence of malignancy in the thyroid remnant (P = .002; relative risk, 4.9; 95% confidence interval, 1.7-14.5). Detection of malignancy in the remnant thyroid tissue did not affect the disease-free survival (P = .39). There were no deaths in patients who underwent reoperative thyroid surgery.

CONCLUSIONS

Only tumor multifocality in the original thyroid lobe was predictive of finding additional cancer in the contralateral lobe. However, clinical significance of occult multifocal disease was not shown.

Prognosis and risk stratification in young papillary thyroid carcinoma patients

Controversies remain regarding to the therapeutic methods of papillary thyroid cancer (PTC) in young patients. TNM staging and other risk evaluation system are not perfectly applicable for all young PTC patients in view of disease outcome. The aims of this study are to identify the clinical presentations, prognostic factors and risk analysis methods. From January, 1977, to June, 2006, seventy-seven patients with primary PTC younger than 20 years old at Chang Gung Medical Center in Taiwan were enrolled in this retrospective study. The patients were classified as disease-free or non-disease-free according to presence or absence of distant metastases or local recurrence at the end of follow-up. Clinical data of these patients were analyzed and compared. The average follow-up period was 10.3 years. Two patients died of PTC during the follow-up period; one died of brain metastasis, and one died of airway obstruction. Patients undergoing total thyroidectomy, especially those with disease beyond the thyroid, had better outcomes than patients not undergoing total thyroidectomy (p = 0.003). Moreover, the DeGroot clinical classification system was a better predictor of prognosis than TNM (p<0.001 vs p = 0.007). Our results suggest that prognosis for PTC is not worse in younger patients. However, patients who had undergone total thyroidectomy might have a better prognosis. Clinical classification is a good alternative classification system for predicting disease outcome in young PTC patients. Patients with confined intrathyroid lesion (<or=T2, N0, M0) may be regarded "low risk" PTC patients.

131I activity for remnant ablation in patients with differentiated thyroid cancer: A systematic review

CONTEXT

Radioiodine ablation of the thyroid remnant after thyroidectomy is commonly performed in the management of patients with differentiated thyroid cancer. Although many centers administer an activity of 100 mCi, there is uncertainty over using a lower activity.

OBJECTIVE

A systematic review of the published literature was used to compare the success rates of remnant ablation using approximately 30 mCi with approximately 100 mCi (1.1 vs. 3.7 GBq).

DATA SOURCES

Data were obtained from MEDLINE and EMBASE for the years 1966 to March 2006.

STUDY SELECTION

All studies that reported rates of successful ablation associated with approximately 30 or approximately 100 mCi of radioiodine were reviewed.

DATA EXTRACTION

Studies were based on reviews of patient case notes (n = 41), prospective cohorts (n = 12), and randomized trials (n = 6). We obtained the success of thyroid remnant ablation according to different administered activities of radioiodine. Where a study reported on two or more activities, the risk ratio of having a successful ablation (approximately 30 vs. approximately 100 mCi) was calculated and combined in a meta-analysis.

DATA SYNTHESIS

Observational studies confirmed the high ablation success rate ( approximately 80%) using approximately 100 mCi, although 22% of studies reported a rate of 90% or greater. The pooled ablation success rate in these studies was 10% lower using 30 mCi compared with 100 mCi (95% confidence interval, 3-17%; P = 0.01). The meta-analysis of the randomized trials produced equivocal results. For example, the rate of successful ablation in patients given 30 mCi was 8% lower compared with 100 mCi (95% confidence interval, 29% lower or up to 20% greater, P = 0.58), consistent with there being no difference or that 30 mCi is much less effective.

CONCLUSIONS

From the published data, it is not possible to reliably determine whether ablation success rates using 30 mCi are similar to using 100 mCi. Large randomized trials are needed to resolve the issue and guide clinical practice.

Management of 131I therapy for thyroid cancer: cumulative dose from in-patients, discharge planning and personnel requirements

AIM

To provide a comprehensive overview with regard to the hospitalization/discharge planning and nursing staff requirements for the management of patients treated with radioiodine for differentiated thyroid carcinoma.

METHODS

A statistical analysis of the fast clearance phase of 131I was performed in 265 hospitalized patients treated after total thyroidectomy with fixed doses ranging from 2590 to 9250 MBq.

RESULTS

Two hundred and twenty-five cases were post-surgical ablation treatments and 40 cases were follow-up treatments. The 131I clearance was studied during hospitalization of 2-4 days. No clearance differences were found between the two groups. The median value of the biological half-time (T1/2bio) was 0.65 days, with a variability range of 0.30-2.03 days. A statistical model for the distribution of T(1/2bio) was reported. Some patients on maintenance haemodialysis were also studied, with T(1/2bio) values ranging from 1.6 to 2.6 days. The weekly cumulative dose to personnel from external exposure, corresponding to the 95th percentile, ranged from 0.1 mSv per GBq of administered activity (mSv x GBq(-1)) with a totally ambulant patient to 5.4 mSv . GBq with a totally helpless patient. With patients on maintenance haemodialysis, these values could increase from 1.2 to 1.7 times. The cumulative dose to close relatives was also estimated. The hospitalization times associated with 75% and 95% probabilities of patient discharge were calculated by varying the residual activity limit from 100 to 800 MBq. Finally, using the median T(1/2bio), personnel requirements were evaluated. With totally ambulant and semi-ambulant patients, about 0.5 and 1.0 personnel units per GBq of weekly administered activity were needed so as not to exceed an annual planning dose of 6 mSv per year. The treatment of patients with higher degrees of dependency was impractical.

CONCLUSIONS

On the basis of statistical analysis, a better organization of in-patient treatment may be obtained, as well as more accurate preliminary evaluations of the cumulative doses to nursing staff and attending personnel, for the management of patients treated with radioiodine for differentiated thyroid carcinoma.

Incidental multifocal papillary microcarcinomas of the thyroid: Is subtotal thyroidectomy combined with radioiodine ablation enough?

BACKGROUND

The extent of thyroid resection and the necessity of lymph node dissection has become an issue of controversy in patients with incidental multifocal papillary microcarcinoma.

METHOD

Between 1993 and 2001 a total of 4120 patients underwent surgery for thyroid diseases: 142 patients showed papillary thyroid cancer of < or = 1 cm, multifocal microcarcinomas were found in 22 patients (15.5%). Twenty patients (17 women, three men, aged 26-71 years) met the inclusion criterion of having pre- and intraoperatively no indication of malignancy (incidentaloma). A limited surgical procedure ranging from bilateral subtotal (n=15), ipsilateral total, contralateral subtotal (n=4) to bilateral total (n=1) thyroidectomy without lymph node dissection was performed. The mean volume of thyroid remnants was 4.3 ml.

RESULTS

In 16/20 (80%) patients, the thyroid remnant was ablated by the first dose of 131I, using 3.7 GBq 131I in 15 patients and 1.85 GBq 131I in one patient. Three patients received a second, and one patient a third radioiodine ablation. All 20 patients remained free from relapse or metastasis, documented by negative 131I whole-body scintigraphy and unmeasurable thyroglobulin levels after thyroid hormone withdrawal in hypothyroidism. One patient died 7 years after the diagnosis of thyroid cancer from primary lung cancer. Median follow-up was 65 months (range, 24-120 months).

CONCLUSION

Subtotal thyroidectomy followed by radioiodine therapy without completion thyroidectomy and lymphadenectomy is a possible option in incidental multifocal microcarcinomas.