The outcome of treatment in differentiated thyroid cancer according to recommendations in current Dutch and American guidelines

OBJECTIVE

Assessment of treatment outcome in current de-escalation for differentiated thyroid cancer (DTC) according to the 2015 Dutch thyroid cancer guidelines (NL-15) and American Thyroid Association guidelines (ATA-15).

DESIGN

Retrospectively, the recommendations of the NL-15 and ATA-15 guidelines were evaluated to estimate potentially adequate, under- and overtreatment of DTC in patients treated in the University Medical Center Groningen between 2007 and 2017.

PATIENTS

A total of 240 patients with a cT1-T3aN0-1aM0 DTC fulfilled the inclusion criteria.

MEASUREMENTS

After actual treatment was given, patients were again categorized according to both guidelines into low, intermediate, or high-risk based on tumour status. Next, they were categorized into a congruent low-risk (n = 60), congruent high-risk (n = 73), or incongruent risk group (n = 107). Follow-up data were used to estimate the proportion of potentially adequate, under-, and overtreatment according to both guidelines.

RESULTS

Comparing treatment recommended by NL-15 and ATA-15 showed significantly more over- and adequate treatment when following NL-15 recommendations, and more undertreatment following ATA-15 (all: p < .001). Subanalysis of the congruent low-risk group showed overtreatment in 64% when following NL-15 guidelines (p < .001). No treatment differences were found in the congruent high-risk group. Undertreatment was most often seen in the incongruent risk group when following ATA-15 (p < .001).

CONCLUSIONS

Low-risk patients were treated too aggressively when following NL-15 recommendations, where the less aggressive ATA-15 approach seemed more adequate. Treatment of intermediate risk DTC patients varies greatly, with a relative higher rate of undertreatment according to the recommendations of the ATA-15, advocating further refining of the risk classification in this patient group.

Postoperative external beam radiotherapy for locoregional control in iodine refractory differentiated thyroid cancer

BACKGROUND

The role of postoperative external beam radiotherapy (EBRT) in patients with residual iodine refractory-differentiated thyroid cancer (IR-DTC) is still inconclusive. The aim of this retrospective study was to evaluate locoregional control (LRC) and overall survival (OS), and potential side effects after postoperative EBRT for both microscopic and macroscopic non-radically resected, locally advanced IR-DTC.

METHODS

Between 1990 and 2016, 49 patients with locally advanced IR-DTC received EBRT for microscopic (R1; n = 28) or macroscopic (R2; n = 21) locoregional residual disease. For more insight into the added effect of EBRT, we performed an intrapatient sub-analysis in 32 patients who had undergone more than 1 surgical intervention, comparing LRC after primary, curative-intended surgery with LRC after repeated surgery plus EBRT. To estimate LRC and OS, we used Kaplan-Meier curves. From 2007 onward, we prospectively recorded toxicity data in our head and neck cancer database (n = 10).

RESULTS

LRC rates 5 years after EBRT were higher for R1 (84.3%) than for R2 (44.9%) residual disease (P = 0.016). The 5-year OS rate after EBRT was 72.1% for R1 and 33.1% for R2 disease (P = 0.003). In the intrapatient analysis (n = 32), LRC rates were 6.3% 5 years after only initial surgery and 77.9% after repeated surgery with EBRT (P < 0.001). Acute toxicity was limited to grade I and II xerostomia, mucositis, and hoarseness; only one patient developed late grade III dysphagia.

CONCLUSIONS

Postoperative EBRT is associated with long-lasting LRC and OS with acceptable toxicity in patients with locally advanced IR-DTC, especially in microscopic residual disease.

Generation and Differentiation of Adult Tissue-Derived Human Thyroid Organoids

Total thyroidectomy as part of thyroid cancer treatment results in hypothyroidism requiring lifelong daily thyroid hormone replacement. Unbalanced hormone levels result in persistent complaints such as fatigue, constipation, and weight increase. Therefore, we aimed to investigate a patient-derived thyroid organoid model with the potential to regenerate the thyroid gland. Murine and human thyroid-derived cells were cultured as organoids capable of self-renewal and which expressed proliferation and putative stem cell and thyroid characteristics, without a change in the expression of thyroid tumor-related genes. These organoids formed thyroid-tissue-resembling structures in culture. (Xeno-)transplantation of 600,000 dispersed organoid cells underneath the kidney capsule of a hypothyroid mouse model resulted in the generation of hormone-producing thyroid-resembling follicles. This study provides evidence that thyroid-lineage-specific cells can form organoids that are able to self-renew and differentiate into functional thyroid tissue. Subsequent (xeno-)transplantation of these thyroid organoids demonstrates a proof of principle for functional miniature gland formation.

Patient-Derived Papillary Thyroid Cancer Organoids for Radioactive Iodine Refractory Screening

Patients with well-differentiated thyroid cancer, especially papillary thyroid cancer (PTC), are treated with surgical resection of the thyroid gland. This is followed by post-operative radioactive iodine (I131), resulting in total thyroid ablation. Unfortunately, about 15-33% of PTC patients are unable to take up I131, limiting further treatment options. The aim of our study was to develop a cancer organoid model with the potential for pre-treatment diagnosis of these I131-resistant patients. PTC tissue from thirteen patients was used to establish a long-term organoid model. These organoids showed a self-renewal potential for at least five passages, suggesting the presence of cancer stem cells. We demonstrated that thyroid specific markers, a PTC marker, and transporters/receptors necessary for iodine uptake and thyroid hormone production were expressed on a gene and protein level. Additionally, we cultured organoids from I131-resistant PTC material from three patients. When comparing PTC organoids to radioactive iodine (RAI)-refractory disease (RAIRD) organoids, a substantial discordance on both a protein and gene expression level was observed, indicating a treatment prediction potential. We showed that patient-derived PTC organoids recapitulate PTC tissue and a RAIRD phenotype. Patient-specific PTC organoids may enable the early identification of I131-resistant patients, in order to reduce RAI overtreatment and its many side effects for thyroid cancer patients.

Outcomes of surgery and postoperative radiation therapy in managing medullary thyroid carcinoma

BACKGROUND AND OBJECTIVES

We evaluated the outcomes of surgery with or without postoperative radiation therapy (PORT) in the management of medullary thyroid carcinoma (MTC).

METHODS

From two tertiary cancer centers, 297 consecutive patients with MTC treated with PORT (n = 46) between 1990 and 2016 or surgery alone (n = 251) between 2000 and 2016 were reviewed.

RESULTS

Ten-year cumulative incidences of locoregional and distant failure were 30.2% and 24.9% in the surgery cohort, and 16.9% and 55.2% in the PORT cohort. In the surgery alone cohort, T4 disease, extrathyroidal extension, N1 disease, extranodal extension (ENE), and residual disease after surgery were associated with local failure. The PORT cohort had significantly higher proportions of patients with T4 disease, N1 disease, ENE, and residual disease.

CONCLUSIONS

High-risk clinical features can help identify patients with MTC at high-risk for local failure after surgery alone. Patients with high-risk clinical features had effective locoregional control after PORT.

Outcomes of multimodal therapy in a large series of patients with anaplastic thyroid cancer

BACKGROUND

The role of radiotherapy (RT) in the treatment of patients with anaplastic thyroid cancer (ATC) for local tumor control is critical because mortality often is secondary to complications of tumor volume rather than metastatic disease. Herein, the authors report the long-term outcomes of RT for patients with ATC.

METHODS

A total of 104 patients with histologically confirmed ATC were identified who presented to the study institution between 1984 and 2017 and who received curative-intent or postoperative RT. Locoregional progression-free survival (LPFS), overall survival (OS), and distant metastasis-free survival were assessed.

RESULTS

The median age of the patients was 63.5 years. The median follow-up was 5.9 months (interquartile range, 2.7-17.0 months) for the entire cohort and 10.6 months (interquartile range, 5.3-40.0 months) for surviving patients. Thirty-one patients (29.8%) had metastatic disease prior to the initiation of RT. Concurrent chemoradiation was administered in 99 patients (95.2%) and 53 patients (51.0%) received trimodal therapy. Systemic therapy included doxorubicin (73.7%), paclitaxel with or without pazopanib (24.3%), and other systemic agents (2.0%). The 1-year OS and LPFS rates were 34.4% and 74.4%, respectively. On multivariate analysis, RT ≥60 Gy was associated with improved LPFS (hazard ratio [HR], 0.135; P = .001) and improved OS (HR, 0.487; P = .004), and trimodal therapy was associated with improved LPFS (HR, 0.060; P = .017). The most commonly observed acute grade 3 adverse events included dermatitis (20%) and mucositis (13%), with no grade 4 subacute or late adverse events noted (adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]).

CONCLUSIONS

RT appears to demonstrate a dose-dependent, persistent LPFS and OS benefit in patients with locally advanced ATC with an acceptable toxicity profile. Aggressive RT should be strongly considered for the treatment of patients with ATC as part of a trimodal treatment approach.

Intensity-Modulated Radiation Therapy With or Without Concurrent Chemotherapy in Nonanaplastic Thyroid Cancer with Unresectable or Gross Residual Disease

BACKGROUND

Differentiated thyroid cancer typically has an indolent clinical course but can cause significant morbidity by local progression. Oncologic surgical resection can be technically difficult due to the proximity to critical normal structures in the neck. Our objective was to review the safety, feasibility, and outcomes of definitive-intent intensity-modulated radiation therapy (IMRT) and to analyze whether patients receiving concurrent chemotherapy (CC-IMRT) had higher rates of disease control and survival over IMRT alone in patients with unresectable or gross residual disease (GRD).

METHODS

Eighty-eight patients with GRD or unresectable nonanaplastic, nonmedullary thyroid cancer treated with definitive-intent IMRT between 2000 and 2015 were identified. Local progression-free survival (LPFS), distant metastasis-free survival (DMFS), and overall survival (OS) were evaluated using the Kaplan-Meier method. Univariate and multivariate analyses using cox regression were used to determine the impact of clinical conditions and treatment on LPFS, DMFS, and OS.

RESULTS

Of the 88 patients identified, 45 (51.1%) were treated CC-IMRT and 43 (48.9%) were treated with IMRT alone. All patients treated with CC-IMRT received weekly doxorubicin (10 mg/m²). The median follow-up among surviving patients was 40.3 months and 29.2 months for all patients. The LPFS at 4 years was 77.3%. Patients receiving CC-IMRT had higher LPFS compared with IMRT alone (CC-IMRT 85.8% vs. IMRT 68.8%, p = 0.036). The 4-year OS was 56.3% for all patients. Patients treated with CC-IMRT had higher OS compared to patients treated with IMRT alone (CC-IMRT 68.0% vs. IMRT 47.0%, p = 0.043). On multivariate analysis, receipt of concurrent chemotherapy was associated with a lower risk of death (HR 0.395, p = 0.019) and lower risk of local failure (HR 0.306, p = 0.042). Grade 3+ acute toxicities occurred in 23.9% of patients, the most frequent being dermatitis (18.2%) and mucositis (9.1%). 17.1% of patients required a percutaneous endoscopic gastrostomy (PEG) tube during or shortly after completion of RT, with 10.1% of patients needing a PEG more than 12 months after therapy. The rates of acute and late toxicities were not statistically higher in the CC-IMRT cohort, although trends towards higher toxicity in the CC-IMRT were present for dermatitis and PEG requirement.

CONCLUSIONS

IMRT is a safe and effective means to achieve local control in patients with unresectable or incompletely resected nonanaplastic, nonmedullary thyroid cancer. Concurrent doxorubicin was not associated with worse toxicity and should be considered in these patients given its potential to improve local control and overall survival.

Additional value of a high sensitive thyroglobulin assay in the follow-up of patients with differentiated thyroid carcinoma

OBJECTIVE

Thyroglobulin (Tg) is an excellent tumour marker, as detectable or increasing Tg levels are highly indicative of persistent or recurrent differentiated thyroid carcinoma (DTC). The clinical value of a highly sensitive (hs)-Tg assay in patients with DTC has not yet been established. The aim of this study was to investigate the additional value of unstimulated hs-Tg measurements (Tg-on) compared to stimulated IRMA-Tg measurements (Tg-off) in the follow-up of patients with DTC.

DESIGN, PATIENTS, MEASUREMENTS

We retrospectively studied patients treated for DTC between 2006 and 2013 and compared hs-Tg and IRMA-Tg measurements. The study group consisted of 99 DTC patients in remission; Tg-on was measured 3 months after remnant ablation and Tg-off 6 months after ablation.

RESULTS

In the study group, 44 patients showed a hs-Tg-on <0·15 μg/l (functional sensitivity); of these, 43 had an IRMA-Tg-off measurement <1·0 μg/l, resulting in a negative predictive value of 97·7% and a positive predictive value of 56·4%.

CONCLUSIONS

The hs-Tg-on measurement is able to predict patients with an IRMA-Tg-off <1·0 μg/l, and therefore decreases the need for Tg stimulation after ablation.