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Variables play role in medullary thyroid carcinoma survival rates
Adults with medullary thyroid carcinoma with a large tumor size, high calcitonin level and cervical metastases have a decreased 5-year survival compared with those with smaller tumors, lower calcitonin levels and no cervical metastases, according to published findings.
Joseph Scharpf, MD, of the Head & Neck Institute at the Cleveland Clinic Foundation, and colleagues evaluated 67 adults (mean age, 51 years; 64% women) with medullary thyroid carcinoma to determine prognostic factors that affect survival and to assess the effect of neck dissection on those outcomes.
All participants had a total thyroidectomy, 37 underwent a unilateral or bilateral central neck dissection, 15 underwent a unilateral or bilateral lateral neck dissection, and 15 had nodes sampled without a component-oriented dissection. Fifty-three participants had identified lymph nodes on pathologic analysis, and 22 of them had metastatic disease in at least one node.
Biochemical cure was assessed in 56 participants with follow-up of more than 60 days, and 71% achieved cure. The likelihood of biochemical cure decreased from 90.09% in participants with low levels of calcitonin (< 141 pg/mL) to 33.3% in participants with higher levels of calcitonin (> 1,986 pg/mL).
At 5 years, overall survival was 89.1%, and disease-free survival was 86.2%. The biochemical recurrence-free survival at 5 years in participants who achieved initial biochemical cure was 89.3%.
The presence of nodal disease reduced the rate of 5-year biochemical survival from 96.2% to 71.4%, and the presence of neck metastases decreased 5-year disease free survival from 87.3% to 84.4% in participants who achieved biochemical cure.
The size of the primary tumor, pretreatment calcitonin level and the number of positive lymph nodes were not associated with overall survival.
Participants who achieved biochemical cure were assessed for variables associated with biochemical recurrence-free survival, and the risk for failure was predicted by size of the primary tumor (P = .02) and the number of positive nodes (P = .02).
The presence of cervical metastases was strongly correlated with preoperative calcitonin levels (P = .01), and the risk for cervical metastatic disease was associated with the size of the primary tumor (P < .01).
The risk for (P < .01) and number of (P < .01) cervical metastases increased with extrathyroidal extension, and angiolymphatic invasion was associated with a higher risk for cervical metastasis (P < .01). Increased tumor size was correlated with the risk for extrathyroidal extension (P < .01) and the risk for lymphovascular invasion (P < .01).
A subset of 50 participants preoperatively staged N0 were also evaluated, and 20 underwent partial or complete central neck dissection. The rate of biochemical cure was lower in participants who underwent prophylactic central neck dissection (68.6%) compared with those who did not (96%; P = .02). No differences were found in the rate of disease-free survival or overall survival at 5 years between participants who did and did not undergo prophylactic central neck dissection.
“[Medullary thyroid carcinoma] is an uncommon thyroid neoplasm,” the researchers wrote. “Primary treatment is surgical and should include at least a total thyroidectomy and complete neck dissection. We cannot show the impact of a lateral neck dissection in patients without obvious disease. However, the results of this study show clearly that increasing tumor size, increasing calcitonin level and cervical metastases are poor prognostic factors. This suggests that patients with larger tumors, higher calcitonin level or unfavorable pathologic findings may deserve prophylactic lateral neck dissections as they are at high risk of metastatic disease. Unfortunately, due to limitations of sample size, this study cannot address the specific size and calcitonin level at which the lateral neck dissection is warranted. Additional studies are needed to define the benefits of prophylactic lateral neck dissection to help specific when it is indicated.” – by Amber Cox
Disclosures: The authors report no relevant financial disclosures.