ETA2022 Poster Presentations Thyroid Cancer CLINICAL 2 (10 abstracts)
1Academic Center for Thyroid Diseases, Department of Internal Medicine, Rotterdam, Netherlands; 2Erasmus Medical Center, Academic Center for Thyroid Diseases, Department of Internal Medicine, Academic Center for Thyroid Diseases, Rotterdam, Netherlands; 3Erasmus MC, University Medical Center, Rotterdam, The Netherlands, Department of Clinical Chemistry and Department of Internal Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands, Department of Clinical Chemistry, Erasmus MC, University Medical Center, Rotterdam, The Netherlands, Netherlands; 4Academic Center for Thyroid Diseases, Department of Endocrinology, Erasmus, Department of Internal Medicine, Rotterdam, Netherlands
Background: Medullary thyroid carcinoma (MTC) is a rare disease accounting for 1-3% of all thyroid carcinomas. Unfortunately, most patients present with metastasized disease: 70% with cervical lymph node metastasis and 5-10% with distant metastasis. Survival strongly correlates with stage of disease at diagnosis, illustrating the need for early diagnosis. Calcitonin is a well-established tumour marker for MTC, but its use in the screening phase is limited by a high rate of false positives. Among thyroid cancer types, progastrin-releasing peptide (proGRP), is specifically expressed in MTC. Therefore, proGRP is a potential tumour marker for MTC. We studied the value of proGRP as a screening marker for MTC, especially in the range where calcitonin is inconclusive.
Methods: To investigate the potential of proGRP as an additional tumour marker in the diagnostic work up for MTC we took a stepwise approach. First, we prospectively collected serum samples of patients with benign thyroid nodules (benign cohort) and measured serum proGRP concentration. Second, we aimed to establish a reference range and cut-off for proGRP in a clinical setting. Hereto, we measured serum proGRP in a cohort of people where blood was drawn for a vitamin B12 measurement (reference cohort). Third, we investigated the correlation between calcitonin and proGRP in a cohort of patients in whom calcitonin was measured. Serum proGRP and calcitonin concentrations were measured using Lumipulse G1200 (Fujirebio) and Immulite 2000XPi (Siemens) respectively.
Results: The mean serum proGRP concentration in the benign cohort (n = 48) was 36.9 pg/ml (95% CI 33.2-40.5, range 17.8 62.3 pg/ml). In the reference cohort (n = 670) mean serum proGRP was 43.9 pg/ml (95% CI 41.2-46.6). The 2.5%-97.5% reference interval was 13.5 124.9 pg/ml, with a 90% CI of the upper limit of 103.5 154.5. There was a strong correlation between calcitonin and proGRP (r=0.814, P < 0.001, n = 212), especially in the calcitonin concentration range above 100 pg/ml (r=0.810, P < 0.001, n = 54). In the calcitonin concentration range of 10-100 pg/ml no correlation (r= -0.161, P = 0.475, n = 22) was found.
Conclusion: Mean proGRP concentration in the benign cohort was within reference ranges of the reference cohort, suggesting a potential role for proGRP as an additional screening marker for MTC. This was confirmed by the good correlation between proGRP and calcitonin in patients with a calcitonin above 100 pg/ml. Further research should determine whether proGRP can be employed as a screening tool to diagnose MTC.