7510 Use Of Tumor Markers And Surgery In The Management Of Medullary Thyroid Cancer During Pregnancy

Abstract Disclosure: M. Garver: None. C. Vaz: None. Introduction: Thyroid cancer is the second most diagnosed cancer during pregnancy, predominantly differentiated thyroid malignancies. [1] MTC during pregnancy is rare and challenging to manage due to its aggressive nature. We describe the successful diagnosis and management of MTC during pregnancy. Clinical Case: A 28 yo woman presented with a rapidly growing neck lump for 2 months with an associated unintentional 10lb weight loss and without compressive symptoms. She had no history of childhood radiation exposure or family history of thyroid cancer. Physical exam revealed a hard L lobe thyroid nodule without palpable lymphadenopathy. The patient was 5 weeks pregnant at the time. A neck US revealed a 4.2x2.7x2.0 cm L solid isoechoic thyroid nodule with punctate echogenic foci and microcalcifications. The nodule was classified as TIRADS 4 and ATA high suspicion. FNA noted Bethesda IV with positive IHC stains for chromogranin and calcitonin. Afirma MTC classifier was positive, confirming diagnosis of MTC. At 7 weeks gestation, calcitonin was markedly elevated at 3508 pg/mL (n <5 pg/mL), CEA 29.5 ng/mL (n <2.5 ng/mL) and calcium 10.3mg/dL (8.6-10.2mg/dL). Plasma normetanephrines were elevated to176 pg/mL (n <148 pg/mL) with normal metanephrines 28 pg/mL (n <57 pg/mL) and normal 24-hour urine metanephrines. CT neck revealed 3.2x2.8cm L thyroid nodule without cervical lymphadenopathy. Due to pregnancy status, additional imaging to assess for metastatic disease was deferred until after delivery. Genetic testing did not identify mutations within the thyroid cancer panel including APC, CHEK2, DICER1, MEN1, PRKAR1A, PTEN, RET, SDHB, SDHD, and TP53. The patient underwent total thyroidectomy with neck dissection at 19 weeks gestation without complication. Two weeks postoperative Calcitonin was 2 pg/mL(n <5 pg/mL) and CEA was undetectable. Conclusions: The effect of pregnancy on MTC is not well studied because of low incidence. Guidelines on the timing of surgery for MTC diagnosed during pregnancy are lacking. While evidence confirms that surgery can be safely postponed until after delivery for low risk differentiated thyroid malignancies, there is no consensus on timing of surgery for MTC. Given the aggressive nature of MTC, along with marked elevation of calcitonin and CEA in this case, surgery was performed in the 2nd trimester with excellent outcome. Data is conflicting on accuracy of calcitonin and CEA during pregnancy, with some reports suggesting falsely high levels due to pregnancy. The sharp decline in calcitonin and CEA 2 weeks postoperatively suggested these were truly elevated due to MTC and unaffected by pregnant status. We suggest that calcitonin and CEA be followed similar to non-pregnant cases with MTC. Resources: 1.Khaled, H. M., Lahloubi, N. A., & Rashad, N. (2016). A review on thyroid cancer during pregnancy: Multitasking is required. Journal of Advanced Research, 7(4), 565–570. Presentation: 6/2/2024