Low iodine diet advice and differentiated thyroid cancer treatment: A historic exploration in three UK centres.

BACKGROUND AND AIMS: Patients with differentiated thyroid cancer are often advised to follow a low iodine diet (LID) one to two weeks before radioiodine remnant ablation (RRA). We describe treatment practices and ablation success rates in centres (C1, C2, C3) in the UK with different approaches to LID advice. METHODS: Historic cohort of patients with differentiated thyroid cancer treated with RRA in 2015/16 in C1 (n = 50, 1-week LID), C2 (n = 59, 2-week LID) and C3 (n = 108, no LID advice). Response to RRA was stratified as excellent, indeterminate, or incomplete by the adapted American Thyroid Association Dynamic Risk Stratification Score. RESULTS: There was little difference in age, sex and staging between centres, but the percentage receiving 1.1 GBq vs higher administered activities differed (C1:22%, C2:44%, C3:15%, p < 0.001). Excellent response was recorded for: C1:48%, C2:36%, C3:49% (p = 0.61). Differences in RRA preparation and outcome assessment at C3 precluded comparison across all centres. Adjusted odds ratio for excellent response at C2 vs C1 was 0.57 (95%CI: 0.25,1.32), p = 0.19. CONCLUSIONS: There was no evidence that advising a LID for 2-weeks before RRA improves outcomes compared to 1-week. For definitive recommendations on LIDs prior to RRA, a prospective multi-centre study with a more homogenous approach to patient management or, randomised controlled trial, is needed.

Experiences of low iodine diets in the treatment of differentiated thyroid cancer with radioactive iodine ablation therapy.

BACKGROUND AND AIMS: International guidelines on the treatment of differentiated thyroid cancers (DTC) promote the use of low iodine diets (LID) prior to radioactive iodine remnant ablation (RIA), as high iodine status may interfere with radioiodine uptake. Most UK treatment centres adhere to these guidelines and advise people to consume a LID. There is limited research as to how people cope with the LID or its impact on daily life and wellbeing, and no studies have been conducted in the UK. This study explored peoples' views and experiences in relation to consuming a LID during treatment for DTC with RIA. METHODS: Twenty-eight semi-structured interviews were conducted with people from across three treatment centres where differing advice had been delivered regarding a LID. Interviews were recorded, transcribed verbatim and key themes were developed through inductive thematic analyses. RESULTS: Individuals advised to consume a LID believed that adhering to the diet would help their treatment. Most restricted their diets beyond what was recommended and there was confusion surrounding what they could eat as part of the diet. Food selection and preparation were important which included substitution of foods and ingredient checking. Being on the diet was considered to have both a physical and psychological impact. CONCLUSIONS: The findings of this study provide a qualitative insight into the lived experiences of people with DTC in relation to consuming a LID. The results have relevance for professionals providing dietary guidance at oncology centres treating patients with RIA therapy in the UK.

A Survey of UK Centres on Low Iodine Diet Recommendations prior to Radioiodine Ablation Therapy for Differentiated Thyroid Cancer.

BACKGROUND: Guidelines suggest that a low iodine diet (LID) is advised prior to radioiodine ablation (RIA) for thyroid cancer. We aim to describe current practice regarding LID advice in the UK, determine uptake of the 2016 UK LID Working Group diet sheet and discover whether there are differences in practice. METHODS: We used an online survey distributed between November 2018 and April 2019 to centres in the UK that administer 131I. We asked questions on whether a LID is advised, for how long, how advice is presented, whether and how compliance is measured and whether treatment is delayed if LID advice is not followed. RESULTS: Fifty-six clinicians from 47 centres that carry out RIA for thyroid cancer responded. Forty-four centres (94%) advise a LID prior to RIA, the majority for 14 days (82%). Two-thirds of the centres use the UK LID Working Group diet sheet. Patients are told to resume normal eating when 131I is administered at 17 centres (39%), with 18 (41%) advising waiting for 24-48 h after administration. Most centres (95%) use only a simple question or do not assess compliance. Only 2 (5%) indicate that RIA would be delayed if someone said they had not followed LID advice. CONCLUSIONS: UK practice regarding LID prior to RIA for thyroid cancer is consistent with current guidelines, but non-adherence does not usually delay RIA. The UK Low Iodine Diet Working Group diet sheet is widely recognised and used. Practice could be improved by centres working to harmonise advice on when to restart a normal diet.