Incidence of Second Cancers in Thyroid Cancer Patients Treated with Radioactive Iodine Ablation: How High Is Really the Risk?

Abstract

Differentiated thyroid cancer (DTC) is a common endocrine tumor with increasing incidence and excellent prognosis. The therapy of thyroid cancer consists of thyroidectomy, thyroid hormone treatment and, depending on pathological stage, adjuvant radioactive iodine ablation (RIA). Because of the excellent outcome of DTC and the potential cancerous effect of iodine-131, in the last years there has been a huge number of articles addressing the issue of the incidence of second tumors in DTC patients. We will make a short critical review of some of these articles focusing on results reporting and interpretation. Methodological factors that may affect the obtained results will be highlighted for the benefit of the reader so that the risk associated to iodine-131 exposure will be balanced to the risk associated to other risk factors, including enhanced medical surveillance, shared genetic variability and environment factors and proper methodological study design. The review is finally a call to physicians involved in the therapy of these patients, primarily nuclear medicine physicians, endocrinologists and surgeons, to join their complimentary skill for the therapy of these patients.

Use of multikinase inhibitors/lenvatinib in patients with synchronous/metachronous cancers coinciding with radioactive‐resistant differentiated thyroid cancer

“…This risk significantly increases linearly with each increment of cumulative iodine‐131 (I 131 ) 10,15,16,18,19,28–30 . However, this correlation has not been fully confirmed 8,31–33 …”

“…Despite the lack of sound clinical evidence, there is sufficient pathophysiological rationale to use MKIs, particularly lenvatinib alone or in combination, for specific combinations of MPMNs, including DTC and most common associated SPCs 48,49,59 . Furthermore, there might be an even greater potential benefit of combining an MKI and a TKI for treatment of advanced malignancies (including DTC) according to therapeutic molecular targets based on common driver gene alterations and/or activated (initial or escape) signaling pathways 24,32–35,44,45,59,60 . For example, lenvatinib has shown promise in the simultaneous management of metastatic RR‐DTC and associated bowel malignancies in a patient with familial adenomatous polyposis 53 .…”

“…10,15,16,18,19,[28][29][30] However, this correlation has not been fully confirmed. 8,[31][32][33] Some studies have also found an increased risk for SPC (including DTC) after external beam radiation therapy (EBRT) for other primary tumors. 31 Accordingly, as the evidence suggests that increased risk for non-thyroid SPC could be related to treatment for DTC, more restricted use of RAI therapy and EBRT in selected DTC patients has been suggested recently, notably for younger patients with low-risk disease.…”

“…3 gene alterations and/or activated (initial or escape) signaling pathways. 24,[32][33][34][35]44,45,59,60 For example, lenvatinib has shown promise in the simultaneous management of metastatic RR-DTC and associated bowel malignancies in a patient with familial adenomatous polyposis. 53 Currently there is an ongoing clinical trial evaluating the usefulness of a therapeutic alternative for MPMN (including DTC) (ClinicalTrials.gov Identifier: NCT04182789.…”

Editorial Review 2016 – Nuclear Medicine, Diagnostic Imaging and Therapy

“…Imaging and Therapy [2]. The authors discuss the role of differentiated thyroid cancer (DTC) which is a common endocrine tumour, the increase of incidents and the availability of a prognosis.…”