Histology-proven recurrence in the lateral or central neck after systematic neck dissection for medullary thyroid cancer

Surgical Treatment of Medullary Thyroid Cancer

Medullary thyroid cancer (MTC) is an infrequent calcitonin-secreting thyroid malignancy that can vary a great deal in tumor biology and progression. The most important determinant of distant metastases, which represents the single greatest risk factor of poor cancer-specific survival, is lymph node metastasis in the neck and mediastinum. In patients with node-positive MTC, systematic compartment-oriented dissection of central and lateral neck nodes at the initial operation promotes biochemical cure and decreases the risk of locoregional recurrence in previously dissected lymph node compartments. Routine calcitonin screening in nodular thyroid disease and genomic screening, flanked by advances in ultrasound and functional imaging modalities, have been pivotal in making the diagnosis early and enabling risk-reducing surgical interventions in patients with sporadic and hereditary MTC, without compromising clinical outcome. To assess a RET carrier's risk of medullary thyroid cancer, all that is needed is patient age, underlying RET mutation, and biomarker levels. Recently, risk-reducing surgery, consisting in hemithyroidectomy with or without diagnostic ipsilateral central lymph node dissection, has been advocated for sporadic MTC clinically confined to one thyroid lobe that is desmoplasia negative on intraoperative frozen sectioning. These recent developments reflect the current shift from reactive to increasingly preemptive, risk-reducing surgery for MTC.

Tumor desmoplasia outperforms preoperative serum calcitonin as surgical biomarker in sporadic medullary thyroid cancer

BACKGROUND

Conceptually, thyroid tumor desmoplasia may be better suited for excluding node metastases in sporadic MTC than preoperative serum calcitonin levels.

METHODS

This analysis included 181 patients with unilateral sporadic MTC graded on the 7-grade desmoplasia scale after thyroidectomy and neck dissection.

RESULTS

When thyroid tumor desmoplasia reached 1% and ≥50%, node metastases increased from 0% to 7% (median of 0 metastases) and 83% (median of 7.5 metastases), microscopic lymphatic invasion from 0% to 3% and 35%, extrathyroid extension from 0% to 5% and 22%, and extranodal growth from 0% to 0% and 44%, whereas biochemical cure declined from 100% to 95% and 25%. Thyroid tumor diameters and basal calcitonin overlapped widely among the seven desmoplasia groups, precluding differentiation by thyroid tumor size or serum calcitonin levels.

CONCLUSIONS

Thyroid tumor desmoplasia, unlike serum calcitonin levels, discriminates extremely well between node-negative and node-positive sporadic MTC, opening new avenues for precision surgery.

Construction and Validation of a Prediction Model for Identifying Clinical Risk Factors of Lateral Lymph Node Metastasis in Medullary Thyroid Carcinoma

PURPOSE

Medullary thyroid carcinoma (MTC) is a rare but highly invasive malignancy, especially in terms of cervical lymph node metastasis. However, the role of prophylactic lateral lymph node dissection (LLND) is still controversial. We hereby aim to explore the risk factors of lateral lymph node metastasis (LLNM) in patients with MTC to guide clinical practice.

PATIENTS AND METHODS

The clinicopathological characteristics of patients with MTC from the Surveillance, Epidemiology, and End Results (SEER) Program and the Second Affiliated Hospital of Chongqing Medical University were reviewed and analyzed. Univariate and multivariate logistics regression analyses were used to screen the risk factors of LLNM in patients with MTC.

RESULTS

Four variables, including male gender, multifocality, extrathyroidal invasion (EI), and large tumor size (all p < 0.05), were identified as potential independent factors of LLNM in patients with MTC. Based on these results, an individualized prediction model was subsequently developed with a satisfied C-index of 0.798, supported by both internal and external validation with a C-index of 0.816 and 0.896, respectively. We also performed the decision curve analysis (DCA) and calibration curve, which indicated a remarkable agreement in our model for predicting the risk of LLNM.

CONCLUSION

We determined that various clinical characteristics, male gender, multifocality, EI, and large tumor size, were significantly associated with LLNM in patients with MTC. Thus, a validated prediction model utilizing readily available variables was successfully established to help clinicians make individualized clinical decisions on MTC management, especially regarding whether the LLND is necessary for patients with clinical negative lateral lymph node involvement and the frequency of follow-up without LLND.

Abandoning node dissection for desmoplasia-negative encapsulated unifocal sporadic medullary thyroid cancer

BACKGROUND

Predictive criteria to determine the absence of node metastases from thyroid specimens are scarce for sporadic medullary thyroid cancer.

METHODS

Histopathologic stratification of patients with unifocal sporadic medullary thyroid cancer ≤25 mm with ≥10 neck nodes at thyroidectomy to evaluate the suitability of desmoplasia (7 increments) and tumor capsule integrity (5 decrements) for intraoperative prediction of node metastasis in unifocal sporadic medullary thyroid cancer.

RESULTS

Paraffin-embedded thyroid specimens were available for 139 eligible patients. Significant (P < .001) associations were found between increasing desmoplasia and decreasing tumor capsule integrity and nodal disease (from 0 to 79% and 0 to 62%); the number of node metastases (medians, from 0 to 3 and 0 to 2 nodes); and biochemical cure (from 100 to 36% and 100 to 58%). Desmoplasia (low-moderate to high, with fibrosis >10%) and breach of the tumor capsule (>3 extensions; 1 extension >3 mm in width; or diffuse growth without tumor capsule) yielded excellent sensitivity and negative predictive value (100%), with moderate specificity (57 and 48%) and positive predictive value (50 and 46%). In retrospect, node dissection proved unnecessary in 55 (57%) and 47 (48%) patients who harbored desmoplasia-negative and encapsulated tumors. When available frozen sections were histopathologically compared with matching paraffin-embedded thyroid tumor specimens, concordance was 98% (53 of 54 pairs): 1 of 7 upgrades changed the diagnosis to desmoplasia, whereas 1 of 3 downgrades shifted the diagnosis of tumor capsule breach from "present" to "absent."

CONCLUSIONS

Patients with desmoplasia-negative encapsulated sporadic medullary thyroid cancer may forgo node dissection at specialist centers.

Medullary thyroid cancer: What is the optimal management of the lateral neck in a node negative patient at index operation?

BACKGROUND

Medullary thyroid cancer is a neuroendocrine malignancy that can occur sporadically or as the result of genomic rearranged during transfection mutations. Medullary thyroid cancer has a higher rate of metastasis than well-differentiated thyroid cancer. Lateral neck dissection is often performed, and its prophylactic use is controversial.

METHODS

Single-center, retrospective review (2000-2017) of patients undergoing primary surgical treatment for medullary thyroid cancer who had negative lateral neck imaging preoperatively. Demographics, genetic associations, clinical, and imaging findings were analyzed. Locoregional recurrence, overall recurrence, and overall survival were examined.

RESULTS

A total of 110 patients were identified, of which 18 underwent prophylactic lateral neck dissection and 92 did not. Age, sex distribution, preoperative calcitonin levels, and follow-up were similar among groups. Overall recurrence was 20% for no prophylactic lateral neck dissection and 39% for prophylactic lateral neck dissection (P = .46). Most recurrences were locoregional recurrence, 7.6% for no prophylactic lateral neck dissection versus 22% for prophylactic lateral neck dissection (P = .08), half of it being to the lateral neck in both groups. A total of 7 patients from the no prophylactic lateral neck dissection group required treatment for recurrences versus 4 patients in prophylactic lateral neck dissection group (P = .57). Overall survival at 5 years was similar, 43% the no prophylactic lateral neck dissection group and 31% for prophylactic lateral neck dissection group (P = .52).

CONCLUSION

Lateral neck dissection has no effect in decreasing locoregional or overall recurrences in medullary thyroid cancer and has no effect in overall survival when performed prophylactically at index surgical intervention.

Prediction of biochemical cure in patients with medullary thyroid cancer

BACKGROUND

The impact of number of node metastases versus metastatic lymph node ratio versus AJCC node category on biochemical cure in medullary thyroid cancer (MTC) is not well defined.

METHODS

Multivariable logistic regression analysis was used to determine clinical and histopathological variables that contribute to biochemical cure in node-positive MTC.

RESULTS

Some 584 of 1026 patients with MTC underwent systematic lymph node dissections for node-positive disease; 27·4 per cent (54 of 197) were biochemically cured after the initial operation and 13·5 per cent (42 of 310 patients) after repeat surgery. Cured patients had significantly less extrathyroid extension (11-14 versus 33·2-55·6 per cent), fewer lymph node metastases (median 2-4 versus 12-16), a lower metastatic lymph node ratio (median 0·05-0·08 versus 0·23-0·28), and were less likely to have AJCC pN1b disease (56-76 versus 89·9-91·6 per cent) and distant metastases (0 versus 28·4-37·1 per cent) than patients who were not cured. Biochemical cure curves advanced steadily up to 7-12 node metastases and a metastatic lymph node ratio of 0·33, eventually levelling off after 16-17 node metastases and metastatic lymph node ratios of 0·45-0·65. In logistic regression analysis, number of lymph node metastases (odds ratio (OR) 17·24 for more than 20 metastases, OR 5·28 for 11-20 metastases, OR 2·22 for 6-10 metastases), preoperative basal serum calcitonin (OR 6·24 for over 1000 pg/ml), reoperation (OR 5·34) and extrathyroid extension (OR 2·42) independently predicted failure to reach biochemical cure.

CONCLUSION

Number of lymph node metastases, unlike metastatic lymph node ratio or AJCC node category, determines likelihood of biochemical cure after initial and repeat surgery for node-positive MTC.