Iodine avidity in papillary and poorly differentiated thyroid cancer is predicted by immunohistochemical and molecular work-up

[helvella]

In order for radio-iodine treatment to work, the radioactive iodine has to be taken into the target tissue.

"Avidity" is how strong the uptake of iodine into the tissue is. The higher the avidity, the better at absorbing iodine, and the more likely the treatment is to be successful.

Hence understanding what factors affect avidity could ensure treatment is more effective, use less radioactive iodine, or both.

(I can't help wondering if there is a parallel strand to be considered. What affects the avidity of non-thyroid tissue? Is there any possibility of reducing the uptake of radioactive iodine by other tissue? Classically, salivary glands have been affected by radioactive iodine treatment.)

Although the paper focusses on radioactive iodine ablation, maybe there are also some lessons to be learned for the much lower dose imaging procedures? Even if they use the same dose, the image quality might be improved if the optimum dose is delivered.

Iodine avidity in papillary and poorly differentiated thyroid cancer is predicted by immunohistochemical and molecular work-up

in European Thyroid Journal

Authors: Joachim N Nilsson, Jonathan Siikanen, Vincenzo Condello, Kenbugul Jatta, Ravi Saini, Christel Hedman, Catharina Ihre Lundgren, and C Christofer Juhlin

DOI: doi.org/10.1530/ETJ-23-0099

Volume/Issue: Volume 12: Issue 4

Article ID: e230099

Online Publication Date: 28 Jul 2023

Abstract

Background

Successful radioiodine treatment of differentiated thyroid cancer requires iodine avidity: that is, the concentration and retention of iodine in cancer tissue. Several parameters have previously been linked with lower iodine avidity. However, a comprehensive analysis of which factors best predict iodine avidity status, and the magnitude of their impact, is lacking.

Methods

Quantitative measurements of iodine avidity in surgical specimens (primary tumour and lymph node metastases) of 28 patients were compared to immunohistochemical expression of the thyroid-stimulating hormone receptor, thyroid peroxidase (TPO), pendrin, sodium–iodide symporter (NIS) and mutational status of BRAF and the TERT promoter. Regression analysis was used to identify independent predictors of poor iodine avidity.

Results

Mutations in BRAF and the TERT promoter were significantly associated with lower iodine avidity for lymph node metastases (18-fold and 10-fold, respectively). Membranous NIS localisation was found only in two cases but was significantly associated with high iodine avidity. TPO expression was significantly correlated with iodine avidity (r = 0.44). The multivariable modelling showed that tumour tissue localisation (primary tumour or lymph node metastasis), histological subtype, TPO and NIS expression and TERT promoter mutation were each independent predictors of iodine avidity that could explain 68% of the observed variation of iodine avidity.

Conclusions

A model based on histological subtype, TPO and NIS expression and TERT promoter mutation, all evaluated on initial surgical material, can predict iodine avidity in thyroid cancer tissue ahead of treatment. This could inform early adaptation with respect to expected treatment effect.

Keywords: thyroid cancer; iodine avidity; TERT; NIS; TPO

Open Access here:

etj.bioscientifica.com/view...

If interested, worth reading the Conclusion in the full paper.

[radd]

helvella,

Another rabbit hole 😁

Iron avidity (not iodine) is a term I’m familiar with, when reducing overload via treatment venesection the ferritin drops below a target level whilst T/S remains elevated. Further venesections can not be carried out until ferritin normalises or haemoglobin risks dropping inducing anaemia in the presence of iron overload.

From your paper posted yesterday. .. 'Iron is essential for proper functioning of all cells in the human body. It is involved in the transfer of oxygen and electrons and is crucial for the activity of numerous enzymes. Two percent of human genes encode iron-binding proteins and 6.5% of all enzymes are directly dependent on iron'. And given this importance I assume it must also play another parallel role in the avidity of iodine and non-thyroid tissues.