Radiological surveillance in multiple endocrine neoplasia type 1: a double-edged sword?

Abstract

ContextMultiple endocrine neoplasia type 1 (MEN1) is a hereditary condition characterised by the predisposition to hyperplasia/tumours of endocrine glands. MEN1-related disease, moreover, malignancy related to MEN1, is increasingly responsible for death in up to two-thirds of patients. Although patients undergo radiological and biochemical surveillance, current recommendations for radiological monitoring are based on non-prospective data with little consensus or evidence demonstrating improved outcome from this approach. Here, we sought to determine whether cumulative radiation exposure as part of the recommended radiological screening programme posed a distinct risk in a cohort of patients with MEN1.Patients and study designA retrospective review of 43 patients with MEN1 attending our institution between 2007 and 2015 was performed. Demographic and clinical information including phenotype was obtained for all patients. We also obtained details regarding all radiological procedures performed as part of MEN1 surveillance or disease localisation. An estimated effective radiation dose (ED) for each individual patient was calculated.ResultsThe mean ED for the total patient cohort was 121 mSv, and the estimated mean lifetime risk of cancer secondary to radiation exposure was 0.49%. Patients with malignant neuroendocrine tumours (NETS) had significantly higher ED levels compared to patients without metastatic disease (P < 0.0022).ConclusionsIn MEN1, radiological surveillance is associated with clinically significant exposure to ionising radiation. In patients with MEN1, multi-modality imaging strategies designed to minimise this exposure should be considered.

Management impact: effects on quality of life and prognosis in MEN1

“…Moreover, the ratio between diagnostic benefits of imaging and risks due to periodical exposure to ionizing radiation should be taken into account. Indeed, recent data have demonstrated to 3-fold increase in the per capita individual radiation exposure from medical diagnostic radiation sources over the past 25 years (Casey et al 2017), and it has been estimated that exposure to ionizing radiation for diagnostic purposes may account for 2% of all tumors (Flasar & Patil 2014). This oncogenic relative risk could also be higher in patients with a genetic tumor-predisposing syndrome, bearing a mutation in genes involved in DNA repair or tumor suppression, such as MEN1, who constantly undergo repeated exposure to diagnostic doses of ionizing radiation (Allan 2008).…”

“…This oncogenic relative risk could also be higher in patients with a genetic tumor-predisposing syndrome, bearing a mutation in genes involved in DNA repair or tumor suppression, such as MEN1, who constantly undergo repeated exposure to diagnostic doses of ionizing radiation (Allan 2008). Very recently, Casey and coworkers (Casey et al 2017), retrospectively investigated, for the first time, the effective dose (ED) of ionizing radiation received by a cohort of 43 MEN1 patients to evaluate if the cumulative radiation exposure in surveillance program increases the oncogenic risk. Authors failed in finding an association between the high mean ED in their cohort and the secondary tumor induction, but that could be due to the relatively short period of the retrospective study (only 8 years).…”

The future: diagnostic and imaging advances in MEN1 therapeutic approaches and management strategies

“…All MEN1 gene mutation carriers and even negative tested patients with a high clinical suspicion for MEN1 should be kept under regular surveillance, ideally in prospective controlled screening programs (Brandi et al 2001, Thakker et al 2012, since such surveillance with a consecutive timely intervention resulted in reduced hormone hypersecretion associated mortality over the last decade (Norton et al 2015, Casey et al 2017.…”

“…However, as MEN1 patients undergo regular surveillance, the radiation exposure of CT has to be taken into consideration. Casey et al (2017), for example, retrospectively analyzed the cumulative radiation exposure of 43 MEN1 patients due to screening and calculated an estimated mean lifetime risk of secondary cancer of 0.49% (Casey et al 2017). Therefore, these authors and several other groups (Ito & Jensen 2016, Casey et al 2017 prefer MRI over CT for the screening/imaging of dpNENs in MEN1 patients.…”

The future: medical advances in MEN1 therapeutic approaches and management strategies

“…In addition to plasma hormonal assessments, yearly radiological imaging studies are advised (Thakker et al 2012). However, one must keep in mind the life-time cumulative radiation exposure when CT scans are used especially for young patients (Casey et al 2017). Therefore, expert centers preferably use magnetic resonance imaging (MRI) (Newey et al 2009, Thakker et al 2012.…”