Prognosis
The prognosis of MTC is poorer than that of follicular and papillary thyroid cancer when it has metastasized (spread) beyond the thyroid gland. Depending on source, the overall 5-year survival rate for medullary thyroid cancer is 80%, 83% or 86%, and the 10-year survival rate is 75%.
By overall cancer staging into stages I to IV, the 5-year survival rate is 100% at stage I, 98% at stage II, 81% at stage III and 28% at stage IV.
The prognostic value of measuring calcitonin and carcinoembryonic antigen (CEA) concentrations in the blood in patients with abnormal calcitonin levels postsurgery has been recently published (2005) in a retrospective study of 65 MTC patients; see Barbet, et al.. The post-surgical times ranged from 2.9 years to 29.5 years; all 65 patients continued to have abnormal calcitonin levels after total thyroidectomy and bilateral lymph node dissection. The prognosis of surviving MTC appears to be correlated with the rate at which a patient's postoperative calcitonin concentration doubles, rather than the pre- or postoperative absolute calcitonin level.
The result of the 65 patient study can be summarized with respect to the calcitonin doubling time (CDT):
CDT < 6 months: 3 patients out of 12 (25%) survived 5 years. 1 patient out of 12 (8%) survived 10 years. All died within 6 months to 13.3 years.
CDT between 6 months and 2 years: 11 patients out of 12 (92%) survived 5 years. 3 patients out of 8 (37%) survived 10 years. 4 patients out of 12 (25%) survived to the end of the study.
CDT > 2 years: 41 patients out of 41 (100%) were alive at the end of the study. These included 1 patient whose calcitonin was stable, and 11 patients who had decreasing calcitonin levels.
The 65 patients had a median age of 51 (range was 6 to 75), with 24 age 45 years or younger and 41 older than 45 years. The gender representation was 31 males and 34 females. All patients shared the following characteristics: 1) had total thyroidectomy and lymph node dissection; 2) had non-zero calcitonin levels after surgery; 3) had at least 4 serum calcitonin measurements after surgery; 4) had a status that could be confirmed at the conclusion of the study.
The same study noted that calcitonin doubling time is a statistically better predictor of MTC survival, compared with CEA.
Read more about this topic: Medullary Thyroid Cancer