Patterns of failure in anaplastic and differentiated thyroid carcinoma treated with intensity-modulated radiotherapy

Patterns of loco-regional progression and patient outcomes after definitive-dose radiation therapy for anaplastic thyroid cancer

BACKGROUND

The aim of this study is to characterize the patterns of loco-regional progression (LRP) and outcomes after definitive-dose intensity modulated radiation therapy (IMRT) for anaplastic thyroid cancer (ATC) with macroscopic neck disease at the time of IMRT.

METHODS

Disease/treatment characteristics and outcomes for patients with unresected or incompletely resected ATC who received IMRT (≥45 Gy) were retrospectively reviewed. For those with LRP after IMRT, progressive/recurrent gross tumor volumes (rGTV) were contoured on diagnostic CTs and co-registered with initial planning CTs using deformable image registration. rGTVs were classified based on established spatial/dosimetric criteria.

RESULTS

Forty patients treated between 2010-2020 formed the cohort. Median IMRT dose was 66 Gy (45-70 Gy); altered fractionation (AF) was used in 24 (60 %). All received concurrent chemotherapy. In addition to areas of gross disease, target volumes (TVs) commonly included: central compartment/upper mediastinum (levels VI/VII), neck levels II-V in an involved, and levels III-IV in an uninvolved lateral neck. Median overall survival was 7.1 m. Median progression free survival was 7.4 m for patients with locoregional disease and 1.8 m for patients with distant metastasis at the time of IMRT. Twenty-one patients (53 %) developed LRP at median of 10.9 m; freedom from LRP at 3 m and 12 m was 71 % (95 %CI 58-87 %) and 47 % (95 %CI 32-68 %). Forty-one individual rGTVs were identified and most occurred within the high dose (HD) TVs: Type A/central HD (n = 29, 71 %) and B/peripheral HD (n = 3, 7 %).

CONCLUSIONS

Despite an intensive treatment schedule, including AF and concurrent chemotherapy, classic radio-resistant and rapid Type A failures predominated; isolated extraneous dose failures were rare. While these findings support the IMRT and TV delineation strategies described herein, they highlight the importance of identifying novel strategies to further improve LRC for patients with unresectable disease without targetable mutations for contemporary neo-adjuvant strategies.

Effect of postoperative radiotherapy for patients with differentiated thyroid cancer

OBJECTIVE

We evaluated the efficacy and safety of postoperative radiotherapy (PORT) for differentiated thyroid cancer (DTC) with high risk features.

MATERIALS AND METHODS

This retrospective study analyzed 187 patients treated for DTC from 1985 to 2019. DTC referred to nonanaplastic thyroid cancer originating from follicular cells. PORT was defined as the administration of external beam radiation to the thyroid and regional lymph nodes following surgery for initially diagnosed DTC. The patients were included in the analysis if they received PORT or exhibited any of the following features: (a) pT4 or pN1b according to the 8th American Joint Committee on Cancer, (b) poorly differentiated thyroid cancer (PDTC), or (c) unfavourable variants such as anaplastic foci and etc. After 1:1 propensity matching, a total of 108 patients were analyzed according to PORT receipt. The median follow-up duration of the matched group was 10.4 years.

RESULTS

After matching, most of the variables became balanced, but the PORT group still had more PDTC and DTC with anaplastic foci. Radioactive iodine (RAI) was less frequently administered in the PORT group. PORT yielded a significantly higher 5-year locoregional recurrence free survival (LRFS) than the No PORT group (5-year LRFS 86.1% vs. 72.7%, p = 0.022), but the 10-year cancer specific survival (CSS) was similar between them (97.8% vs. 85.9%, p = 0.122). The multivariable analysis indicated that PORT was a favourable prognostic factor (Hazard ratio 0.3, 95% Confidence interval 0.1-0.8, p = 0.02) for LRFS, but not for CSS. Among 133 patients without PORT for initial disease, 39 of them received salvage surgery followed by salvage PORT. No severe toxicity after PORT was reported.

CONCLUSION

PORT reduced locoregional recurrence in DTC patients without severe toxicity. PORT can be an effective and safe treatment to improve locoregional control in DTC with high risk features. However, further study is warranted to identify those who can benefit from PORT.

Anaplastic Thyroid Carcinoma: An Update

Anaplastic thyroid carcinoma (ATC) is a rare and undifferentiated form of thyroid cancer. Its prognosis is poor: the median overall survival (OS) of patients varies from 4 to 10 months after diagnosis. However, a doubling of the OS time may be possible owing to a more systematic use of molecular tests for targeted therapies and integration of fast-track dedicated care pathways for these patients in tertiary centers. The diagnostic confirmation, if needed, requires an urgent biopsy reread by an expert pathologist with additional immunohistochemical and molecular analyses. Therapeutic management, defined in multidisciplinary meetings, respecting the patient's choice, must start within days following diagnosis. For localized disease diagnosed after primary surgical treatment, adjuvant chemo-radiotherapy is recommended. In the event of locally advanced or metastatic disease, the prognosis is very poor. Treatment should then involve chemotherapy or targeted therapy and decompressive cervical radiotherapy. Here we will review current knowledge on ATC and provide perspectives to improve the management of this deadly disease.

Outcomes and Patterns of Recurrence for Anaplastic Thyroid Cancer Treated with Comprehensive Chemoradiotherapy

PURPOSE/OBJECTIVES

Radiotherapy (RT) plays an important role in locoregional tumor control for anaplastic thyroid cancer (ATC). Due to its rarity, RT guidelines for ATC are lacking. We describe ATC patterns of nodal disease at presentation and progression and propose corresponding RT target volumes.

MATERIALS/METHODS

We identified all patients with ATC treated at our institution with definitive or adjuvant IMRT and concomitant chemotherapy from 2006 to 2020. We identified in-field, marginal, and out-of-field sites of locoregional recurrence and progression (LRR).

RESULTS

Forty-seven patients met inclusion. Median follow-up was 6.6 months (IQR: 1.9-19.6). Nodal levels involved at presentation included: IB (2.1%), II (23.4%), III (21.3%), IV (21.3%), V (12.8%), VI (34%), and mediastinal (6.4%). All patients received elective nodal RT to levels II-IV and VI. RT volumes also included: IA (23.4%), IB (44.7%), V (87.2%), retropharyngeal/retrostyloid (RP/RS) (27.7%), and mediastinal 1-6 (53.2%). Cumulative incidence of LRR at 3- and 12-months was 26.1% (95% CI: 15.9-42.8) and 35.7% (23.9-53.4). Isolated LRR risk at 3- and 12-months was 6.5% (2.2-19.8) and 8.9% (3.4-22.9). Fourteen (29.8%) patients experienced in-field LRR in the thyroid gland or postoperative tumor bed, II-IV, VI, and mediastinal 1 and 3A. Four (8.5%) patients had marginal LRRs, 3 of whom progressed in the mediastinum at 2, 3P, 4, and 6. Two (4.3%) patients experienced out-of-field LRRs. Throughout the pre-treatment and follow-up period, no patients had disease at IA and 1 (2.1%) patient each had disease at IB and RP/RS. No baseline or treatment characteristics, including RT dose (stratified by < or ≥66 Gy), were significant predictors of LRR on univariate analysis.

CONCLUSIONS

Isolated LRR risk in patients with ATC treated with comprehensive RT and chemotherapy is low. Aggressive multimodality therapy should be reserved for willing, fit patients with no or limited distant disease burden. When treating comprehensively, complete inclusion of mediastinal levels 1-6 may be warranted to avoid marginal disease progression. Omission of levels I and RP/RS can be considered.

[Efficacy and tolerance of salvage curative radiotherapy for patients with cervical relapse of differentiated thyroid carcinoma]

PURPOSE

Radiation therapy is often the last resource treatment for cervical relapse in iodine refractory differentiated thyroid cancer. We present locoregional control data in patients with cervical relapse treated with curative intent radiation therapy with or without concomitant carboplatin.

MATERIAL AND METHODS

This monocentric retrospective study gathered data on patients with differentiated thyroid carcinoma - vesicular or papillary - in relapse after thyroidectomy who received a curative intent cervical radiation therapy. Locoregional progression free survival (LRPFS), progression free survival (PFS), overall survival (OS) were gathered as well as acute and chronic adverse events assessed with the CTCAE v4.

RESULTS

Thirty-nine patients were consecutively included between 2005 and 2019. The median follow-up was 36.6months. Fifteen patients (38%) had a locoregional relapse, locoregional control at 2years was 66.7%. The median LRPFS was 48months [32.9-not reached] and the median overall survival 49months [38.8-not reached]. In multivariate analysis, initial incomplete resection was associated with poorer OS (HR: 24.39 [3.57-166.78], P=0.00113) and LRPFS (HR: 33.91 [4.46-257.61], P=0.00066), extra nodal spread was associated with poorer LRPFS (HR: 13.45 [1.81-99,76], P=0.011). ECOG performance status was associated with OS (HR: 5.11 [1.57-16.66], P=0.00688). Carboplatin association with radiation therapy was not associated with improved survivals (OS: P=0.34, LRPFS: P=0.84). The rate of acute grade 3 toxicities was 14%.

CONCLUSION

Salvage cervical radiation therapy was associated with a locoregional control of 66.7% at 2years with a reasonable toxicity rate. Carboplatin association with radiation therapy did not improve locoregional control nor overall survival in comparison with radiotherapy alone.

Locoregional relapses in the ACCORD 12/0405-PRODIGE 02 study: Dosimetric study and risk factors

PURPOSE

The aim of this study is to correlate locoregional relapse with radiation therapy volumes in patients with rectal cancer treated with neoadjuvant chemoradiation in the ACCORD 12/0405-PRODIGE 02 trial.

PATIENTS AND METHODS

We identified patients who had a locoregional relapse included in ACCORD 12's database. We studied their clinical, radiological, and dosimetric data to analyze the dose received by the area of relapse.

RESULTS

39 patients (6.5%) presented 54 locoregional relapses. Most of the relapses were in-field (n = 21, 39%) or marginal (n = 13, 24%) with only six out-of-field (11%), 14 could not be evaluated. Most of them happened in the anastomosis, the perirectal space, and the usual lymphatic drainage areas (presacral and posterior lateral lymph nodes). Only patients treated for a lower rectum adenocarcinoma had a relapse outside of the treated volume. 2 patients with T4 tumors extending into anterior pelvic organs had relapses in anterior lateral and external iliac lymph nodes.

CONCLUSIONS

Lowering the upper limit of the treatment field for low rectal tumors increased the risk of out of the field recurrence. For very low tumors, including the inguinal lymph nodes in the treated volume should be considered. Recording locoregional involvement, treated volumes, and relapse areas in future prospective trials would be of paramount interest to refine delineation guidelines.

External Beam Radiation Therapy in pT4 Well-Differentiated Thyroid Cancer: A Population-Based Study of 405 Patients

PURPOSE

The benefit of external beam radiation therapy (EBRT) in locally advanced, well- differentiated thyroid cancer (WDTC) is uncertain. The purpose of this study is to evaluate locoregional recurrence (LRR), progression-free survival, and cause-specific survival (CSS) of patients with pT4 well-differentiated thyroid carcinoma.

METHODS AND MATERIALS

A population-based retrospective review was conducted of consecutive patients with pT4 WDTC (per the American Joint Committee on Cancer, 8th edition, criteria) treated provincially between 1985 and 2013. The primary endpoints were cumulative incidence of LRR and CSS. To account for the competing risks of death from other causes, a Fine-Gray's test was used. A Cox-proportional hazards model was used to analyze overall survival (OS). Multivariate models and propensity matching were used to account for the effects of covariates.

RESULTS

A total of 405 patients were identified with a median follow-up time of 14.3 years for a total of 4209 person-years of follow up. The median age at the time of diagnosis was 53 years (range, 20-87). There were 211 patients (52%) who received EBRT. EBRT was associated with age ≥55 years (56% vs 35%; P < .001), airway involvement (42% vs 8%; P < .001), and R1/2 resection (81% vs 51%; P < .001). The 10-year outcomes for the non-EBRT and EBRT groups were 21.6% versus 11.4%, respectively, for LRR, 84.1% versus 93.1%, respectively, for CSS, and 85.7% versus 67.5%, respectively, for OS. On multivariate analysis, EBRT was associated with a lower rate of LRR (hazard ratio [HR]: 0.334; P < .001), but not associated with CSS (HR: 1.56; P = .142) nor OS (HR: 1.216; P = .335). After propensity score matching, the EBRT cohort had lower rates of LRR relative to the non-EBRT cohort (HR: 0.261; P = .0003), but there were no differences in CSS or OS.

CONCLUSIONS

In this large, population-based analysis of patients with pT4 WDTC, EBRT was associated with lower rates of LRR, but no difference in CSS or OS.

Hypofractionated Radiotherapy for Anaplastic Thyroid Cancer: Systematic Review and Pooled Analysis

Anaplastic thyroid carcinoma (ATC) is associated with a poor prognosis due to aggressive tumor growth and high treatment resistance. Hypofractionated treatment concepts may be more effective and less time consuming compared to normofractionated radiotherapy (RT). In this retrospective study, we aim to evaluate the outcome of hypofractionated regimens and perform a systematic review concerning hypofractionated RT and pooled analysis of this treatment modality. A systematic review using the MEDLINE/Pubmed and Cochrane databases was performed. Data from all eligible studies were extracted, and a pooled analysis of literature and our cohort (n = 60) was carried out to examine patient characteristics, toxicity, and outcomes of patients with ATC. As a result, median overall survival (OS) of the single center cohort was four (range 1-12) months. Survival rates at one, three, and six months were 82%, 55%, and 36%, respectively. In univariate analyses, multimodal treatment (p = 0.006) and gender (p = 0.04) were correlated with an improved OS. Six studies with a total number of 152 patients undergoing hypofractionated RT treatment were analyzed. The pooled analysis included four patient cohorts with 60 patients and showed median OS of 5.3 (range: 1-24) months. Multimodal treatment (p < 0.001) and a cumulative radiation dose ≥50 Gy in equivalent dose in 2 Gy fractions (EQD2) (p = 0.014) correlated with an improved OS. On multivariate analysis, multimodal treatment (p = 0.003, hazard ratio (HR): 0.636, 95% confidence interval (CI): 0.469-0.861) was an independent predictor for longer OS. After propensity score matching (PSM), hypofractionated RT appears to be non-inferior compared to normofractionated RT concerning OS. In conclusion, hypofractionated RT is effective with manageable toxicity. A dose escalation with ≥50 Gy (EQD2) correlated with a longer OS. Hypofractionated RT could be an integral part in multimodal treatment with a promising outcome.

Adjuvant external beam radiotherapy for surgically resected, nonmetastatic anaplastic thyroid cancer

BACKGROUND

EBRT in resected, nonmetastatic anaplastic thyroid cancer (ATC) remains undefined. We evaluated patterns/outcomes with EBRT and chemotherapy in this setting.

METHODS

This retrospective analysis included patients identified from the National Cancer Database with nonmetastatic ATC from 2004 to 2014 who underwent non-palliative resection.

RESULTS

Our analysis included 496 patients, including 375 who underwent adjuvant EBRT (among whom 198 received concurrent chemotherapy). The median age was 68 years. On MVA, EBRT was associated with sex (OR 0.5, 95% CI 0.3-0.8, P = .002) and income (OR 2.2, 95% CI 1.4-3.3, P < .001). EBRT was associated with longer OS on UVA (12.3 vs 9.1 months, P = .004) and MVA (HR 0.7 [CI 0.6-0.9], P = .004). Concurrent chemoradiation was associated with longer OS on UVA (14.0 vs 9.1 months, P = .003) and MVA (HR 0.6 [CI 0.5-0.8], P < .001).

CONCLUSION

Adjuvant EBRT is associated with longer OS in resected, nonmetastatic ATC, with additional improved survival with concurrent chemotherapy.