Prophylactic Thyroidectomy for Hereditary Medullary Thyroid Carcinoma: A 40 Year Followup Study

Program: Abstracts - Orals, Poster Previews, and Posters
Session: SAT 270-310-Thyroid Neoplasia (posters)
Saturday, April 2, 2016: 1:15 PM-3:15 PM
Exhibit/Poster Hall (BCEC)

Poster Board SAT 294
Elizabeth G Grubbs*1, Ronald M Lechan2, Beth Edeiken-Monroe3, Chardria S Trotter3, Frances Nieves-Munoz3, Arthur S Tischler2 and Robert F Gagel1
1The University of Texas MD Anderson Cancer Center, Houston, TX, 2Tufts Medical Center, Boston, MA, 3University of Texas M.D. Anderson Cancer Center, Houston, TX
Forty years ago physicians and family members of the J-kindred, a 100+ member family with Multiple Endocrine Neoplasia type 2A, proposed a bold experiment – to test the hypothesis that total thyroidectomy and central lymph node dissection could cure MTC in children/young adults at risk for hereditary MTC. A prior report (1988) provided an optimistic assessment of outcomes at a mean of 11 years after thyroidectomy (1). We recently re-examined 18 of 22 family members (4 declined but are alive and well) with proven RET proto-oncogene mutations (C634G) who underwent thyroidectomy 1972 -1994 based on pentagastrin-stimulated calcitonin  (CTN) abnormalities. Their median age at thyroidectomy was 16.5 yrs (range 9-24 years). The median followup duration was 40 yrs (range 21-34) with a mean current age of 52 yrs. Each of the 18 patients had a basal serum CTN (performed by a 2-site chemiluminescent assay with a sensitivity of 2 pg/ml) and albumin-corrected serum calcium; 16 of 18 had a high resolution ultrasound of the neck performed by an experienced ultrasonographist who was blinded to the clinical status of the patients. Fifteen of 18 patients had no detectable serum CTN (<2 pg/ml); three had low level (<60 pg/ml) serum CTN values. One operated at age 15 years had recurrent MTC treated by extensive lymph node dissection at age 30 years and currently has a serum CTN of 10 pg/ml. The second, operated upon at age 15, years has a current serum CTN of 10 pg/ml, a value unchanged for the past 16 years. A third, operated upon at age 9  yrs, has a serum CTN value that has risen from 19 to 56 pg/ml l over the past 14 yrs with no evidence of recurrent disease by ultrasound. Seven of the 18 patients had C cell hyperplasia and 11 had microscopic MTC at the time of primary surgery; the 3 with detectable calcitonin values had microscopic MTC without lymph node metastasis on their initial operative pathology. None of the 16 patients examined during the 40 yr followup, including 2 of 3 with elevated CTN values, had an abnormality noted by the current ultrasound examination. None of the 18 has developed hyperparathyroidism. The findings show that early thyroidectomy has cured 15 of 18 patients (83%) at risk for development of MTC with a median follow up period of 40 years. Three patients, ages 9, 15 and 15 years at thyroidectomy, have detectable serum CTN and presumed metastasis, but without current evidence of radiographically evident MTC. None of the prospectively screened family members has died from this syndrome. We conclude that early thyroidectomy and central lymph node dissection is effective treatment for hereditary MTC. However, the identification of recurrent calcitonin elevations in a child operated at 9 years of age underscores the importance of performing a thyroidectomy by age 5 years in children with a codon 634 RET proto-oncogene mutation, reflecting current American Thyroid Association guidelines for use of RET genetic testing information.

(1) Gagel RF et al., N Engl J Med 1988: 318:478.

Nothing to Disclose: EGG, RML, BE, CST, FN, AST, RFG

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