Prognostic Impact of Direct 131I Therapy After Detection of Biochemical Recurrence in Intermediate or High-Risk Differentiated Thyroid Cancer: A Retrospective Cohort Study

Abstract

Background: Patients treated for intermediate- or high-risk differentiated thyroid carcinoma (DTC) and Thyroglobulin (TG) elevation during follow-up, require a diagnostic whole-body scan (DWBS) and if positive, 131I treatment. This approach can lead to a delay in treatment and increased costs. The purpose of this study is to compare the oncologic outcomes associated to administration of direct therapy with 131I at first biochemical recurrence.Methods: Retrospective cohort study of patients with intermediate- or high-risk DTC treated with total thyroidectomy, 131I ablation and who developed TG elevation during follow-up, between January 2007 and December 2015. Cohort A included patients who underwent a DWBS with 5 mCi of 131I, and if negative an MRI and/or 18FDG PET-CT prior to the therapeutic dosage, and cohort B included those who only received a therapeutic dosage of 131I, without a DWBS or extensive image studies. Main outcomes were second recurrence (SR) and disease-free survival (DFS). The diagnostic accuracy of DWBS was analyzed.Results: Cohorts A and B had 74 and 41 patients, each. By multivariate analysis, age, differentiation grade, TN classification, ablation dose, and performed DWBS (odds ratio 55.1; 95% CI 11.3–269) were associated with SR (p < 0.0001); age, male gender, ablation dose and performed DWBS (hazard ratio 7.79; 95% CI 3.67–16.5) were independent factors associated with DFS (p < 0.0001). DWBS diagnostic accuracy was 36.48%.Conclusion: 131I treatment in patients with DTC biochemical recurrence and no DWBS or extensive image studies is associated with a significantly lower frequency of SR and an increased DFS. The diagnostic accuracy of DWBS is low, and its clinical efficiency should be defined in prospective phase III studies.

Personalized Dosimetry in the Context of Radioiodine Therapy for Differentiated Thyroid Cancer

“…In other patients, the symptoms could lead to chronic radiation sialadenitis. These complications are clinically significant in 10–30% of subjects even if their frequency is not well known [ 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. In particular, in the prospective cohort study by Hyer et al, patients were treated with an ablative activity of 3GBq and a further of 5.5 GBq in case of residual disease.…”

“…Today, thyroid cancer is presented at an earlier stage and has a lower recurrence rate of 3–10% [ 51 , 52 , 53 , 54 ]. Moreover, Carrillo et al demonstrated that patients with DTC treated with 131 I, which have a biochemical recurrence and no diagnostic WBS (DWBS) or extensive studies, have lower frequencies of second recurrence (SR) compared to the group that, prior RAIT, underwent a DWBS with 5 mCi of 131 I and Magnetic Resonance Imaging (MRI) and/or 18F-FDG PET if DWBS was negative [ 55 ]. In a study by Rubino et al, second primary malignancies (SPM) and leukemia risk were evaluated.…”

Comparing lesion detection efficacy and image quality across different PET system generations to optimize the iodine-124 PET protocol for recurrent thyroid cancer

“…Radioiodine therapy (1.85–7.40 GBq) is performed if radioiodine-avid lesions are identified. However, diagnostic whole-body scans are limited, e.g., by a low diagnostic accuracy of 36% in biochemical recurrent intermediate- or high-risk DTC patients [ 5 ]. A suitable alternative is iodine-124 ( 124 I) positron emission tomography (PET) imaging.…”