At univariate analysis, the cure was achieved more frequently in more recently operated patients (64.5% vs 38.6%; p = 0.0012), in disease staging I/II (86.5% vs 13.5%; p < 0.0001), in patients undergoing preoperative calcitonin screening (63.8% vs 23.5%; p < 0.0001) and in the absence of lymph node metastases (86.5% vs 13.5%; p < 0.0001).
Postoperative RET gene test and pathological analysis were performed with the surgical specimens; serum calcitonin (Ctn) and carcinoembryonic antigen (CEA) levels were tested pre- and postoperatively, to evaluate the association between RET mutations and cervical lymph node metastasis in MTC.
Formalin-fixed, paraffin-embedded primary thyroid tumors and lymph node metastases from MTC patients were evaluated for calcitonin, RB, and phosphorylated RB (pRB) expression by immunohistochemistry.
In patients with established primary tumors, systematic surgical removal of lymph node basins (compartmental dissection) should be guided by ultrasound mapping of lymph node metastases and level of serum calcitonin.
At primary surgery, all patients (n = 13) with lymph node metastases had preoperative basal calcitonin levels ≥68 pg/mL, and all patients (n = 17) without central lymph node dissection and preoperative basal calcitonin <40 pg/mL were biochemically cured.
At enrollment, high miR-21 levels were associated with high calcitonin levels (P = .0003), lymph node metastases (P = .001), and advanced stages (P = .0003).
Patients with thyroid tumor >5 mm detected by ultrasound, and basal calcitonin levels >40 pg/ml, frequently have cervical and upper mediastinal lymph node metastasis.
Significantly associated determinants of outcome in univariate analysis were higher age at surgery, no age-appropriate prophylactic surgery according to risk level, elevated preoperative calcitonin levels, affected codon, and the presence of lymph node metastases at surgery.
Among patients with lymph node involvement, undetectable calcitonin level was obtained in 57% of patients with less than or with 10 lymph node metastases and in 4% of patients with more than 10 (P < 0.01).
The two groups did not differ in terms of multifocality of MTC (pT1b), lymph node involvement (pN1) or bilateral lymph node metastasis (pN1b), or preoperative stimulated and postoperative basal and stimulated serum calcitonin.