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

Abstract

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 intra-patient sub-analysis in 32 patients who had undergone more than one 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 onwards, we prospectively recorded toxicity data in our head and neck cancer database (n=10). Results: LRC rates five years after EBRT were higher for R1 (84.3%) than for R2 (44.9%) residual disease (p=0.016). The five-year OS rate after EBRT was 72.1% for R1 and 33.1% for R2 disease (p=0.003). In the intra-patient analysis (n=32) LRC rates were 6.3% five 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 locoregional control and overall survival with acceptable toxicity in patients with locally advanced IR-DTC, especially in microscopic residual disease.

External beam radiation therapy for recurrent or residual thyroid cancer: What is the best treatment time and the best candidate for long‐term local disease control?

“…Our study showed that patients with macroscopic residual disease had a greater rate of cervical progression and a shorter duration of local disease control (62.1 vs. 36.7, p = 0.05). Other studies have also shown a benefit of LR control after cervical EBRT in patients with residual microscopic disease versus gross disease 16–18 . In the study by Groen et al, 18 a comparison of local regional disease incidence at 1.5 and 10 years revealed better cervical disease control in patients with microscopic positive margins than in patients with macroscopic positive margins ( p = 0.016).…”

“…Other studies have also shown a benefit of LR control after cervical EBRT in patients with residual microscopic disease versus gross disease. [16][17][18] In the study by Groen et al, 18 a comparison of local regional disease incidence at 1.5 and 10 years revealed better cervical disease control in patients with microscopic positive margins than in patients with macroscopic positive margins (p = 0.016). This finding reinforces the importance of "more complete as possible" surgery, as the rates of local disease control were lower at macroscopic margins even with adjuvant treatment with RAI, systemic therapy and all other modalities usually performed after surgery.…”

External Beam Radiotherapy in Differentiated Thyroid Cancer

“…Both these studies reported superior loco-regional control with EBRT [12,13]. In another retrospective study by Groen et al, 5 year LRC was 84.3% with EBRT (66 Gy) for microscopic residual disease [14].…”

Kết quả xạ trị điều biến liều ở bệnh nhân ung thư tuyến giáp thể biệt hóa kháng I-131 tái phát, di căn vùng cổ ngực

“…Tuy nhiên, các nghiên cứu này chủ yếu thực hiện trên nhóm BN UTTG thể biệt hóa tiến triển tại chỗ, tại vùng, còn ít nghiên cứu về vai trò của xạ trị chiếu ngoài đối với nhóm BN UTTG thể biệt hóa kháng I-131 [5][6][7][8][9][10]. Một vài nghiên cứu đã cho thấy của xạ trị điều biến liều (IMRT) giúp cải thiện kiểm soát tại chỗ, tại vùng cũng như giảm độc tính trong điều trị BN UTTG thể biệt hóa tái phát, di căn [8,10], kháng I-131 [11]…”

“…Một số nghiên cứu hồi cứu cũng đã cho thấy hiệu quả của xạ trị chiếu ngoài về cải thiện thời gian sống còn và khả năng kiểm soát tại chỗ, tại vùng trong điều trị UTTG thể biệt hóa, tiến triển kháng I-131 [11]. Nghiên cứu này của chúng tôi đã cho thấy IMRT giúp cải thiện đáng kể khả năng kiểm soát tại chỗ tại vùng (LRC) và thời gian sống còn toàn bộ (OS) ở nhóm BN UTTG thể biệt hóa kháng I-131 tái phát, di căn vùng cổ-ngực.…”