Different outcomes in sporadic versus familial medullary thyroid cancer.

Background Medullary thyroid carcinoma (MTC) has varying clinical course with familial cases (fMTC) diagnosed earlier than sporadic MTC (spMTC). Methods A total of 273 MTCs (familial: n = 110 [40.3%], males: 38.5%) were followed for 1-35 years (median 5.0 years). Fifty one of the familial cases were operated because of positive findings at genetic screening. Disease extent at diagnosis and follow-up was recorded. Results Mean age at diagnosis was: fMTC = 33.85 +/- 16.5 years (range 4-74) and spMTC = 52.6 +/- 14.0 years (range 16-81, P < .001). This difference remained when genetic screening cases were excluded. fMTCs had more frequently multifocality, smaller size, and more favorable stage at diagnosis (stages I and II: 60.9% vs 47.9%, stage III: 30.0% vs 23.9%, stage IV: 9.1% vs 28.9%, P = .01). fMTC had lower preoperative and postoperative calcitonin, more frequently remission (59.1% vs 47.2%) and less frequently progressive disease (8.2% vs 35.0%, P < .001). After excluding genetic screening cases, no difference in stage at diagnosis was observed. Outcome was more favorable in fMTC compared to sporadic (P = .002); the 10-year probability of lack of progression of disease differed significantly between fMTCs and spMTCs (86.4% vs 65.0%, P < .001). Conclusion After excluding genetic screening cases, although stage at diagnosis is similar, disease outcome remains worse in sporadic compared to fMTCs.