Microsurgical neck dissection for metastasizing medullary thyroid carcinoma

Biochemical cure after reoperations for medullary thyroid carcinoma: a meta-analysis

BACKGROUND

Despite meticulous surgical techniques, calcitonin levels remain detectable in 40 % to 66 % of patients after initial surgery for medullary thyroid carcinoma (MTC), and the optimal surgical management for persistent or recurrent disease remains controversial. Previous studies suggest that biochemical cure, defined by normalization of postoperative calcitonin measurements, predicts disease-free survival. Reoperative approaches range from targeted removal of detectable disease to comprehensive compartment-oriented lymph node clearance.

METHODS

A proportional meta-analysis of clinical case series of postoperative calcitonin clearance after reoperation for MTC was performed. Studies were obtained from PubMed, Embase, Scopus, and the Cochrane Library.

RESULTS

Twenty-seven articles capturing data of 984 patients met the inclusion criteria for the meta-analysis. Overall, normalization of calcitonin after reoperation for MTC occurred in 16.2 % of patients [95 % confidence interval (CI) 14.0-18.5]. Stratified by operative procedure, targeted selective lymph node removal procedures had a normalization of calcitonin in 10.5 % of patients (95 % CI 6.4-14.7), while compartment-oriented procedures had a higher rate of normalization at 18.6 % (95 % CI 15.9-21.3).

CONCLUSIONS

The rate of calcitonin normalization after reoperation for MTC is enhanced through use of a meticulous compartment-oriented lymph node dissection. Compartment-oriented lymph node dissection results in calcitonin normalization in 18.6 % of reoperative MTC patients and is the procedure of choice in patients in whom the goal is biochemical cure.

Locoregional control in patients with palpable medullary thyroid cancer: results of standardized compartment-oriented surgery

BACKGROUND

Extent of neck dissection is controversial in patients with palpable medullary thyroid cancer (MTC).

METHODS

We evaluated 64 MTC patients (19 hereditary, 45 sporadic) with palpable thyroid nodules (group 1, n = 35) or palpable lymph node metastases (group 2, n = 29). Standard surgery included total thyroidectomy, central compartment dissection, and additional neck dissection on indication.

RESULTS

In group 1, 40% of the patients were cured. Thirty-one percent of all patients had central, 23% ipsilateral, 14% contralateral, and 14% mediastinal, metastases. Fifty-one percent developed locoregional recurrence. Locoregional recurrence (p = .043) and reoperations (p = .020) were noted more often after a less than standard initial procedure. In group 2, no patients were cured. All had central, 93% ipsilateral, 45% contralateral, and 52% mediastinal metastases. Thirty-eight percent developed locoregional recurrence.

CONCLUSIONS

Locoregional recurrence frequently occurs in palpable MTC, and tumor control may be improved by standard central, bilateral, and upper mediastinal neck dissection.

Evidence-based approach to the management of sporadic medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare malignancy of the thyroid C cells. It occurs in hereditary (25% of cases) and sporadic (75%) forms. Sporadic MTCs frequently metastasize to cervical lymph nodes. Thorough surgical extirpation of the primary tumor and nodal metastases by compartment-oriented resection has been the mainstay of treatment (level IV evidence). Surgical resection of residual and recurrent disease is effective in reducing calcitonin levels and controlling complications of central neck disease (level IV evidence). Radioactive iodine, external beam radiation therapy, and conventional chemotherapy have not been effective. Newer systemic treatments, with agents that target abnormal RET proteins hold promise and are being tested in clinical trials for patients with metastatic disease.

Angiography-proven liver metastases explain low efficacy of lymph node dissections in medullary thyroid cancer patients

AIM

To report the role of liver angiography in the staging of medullary thyroid cancer (MTC) patients.

MATERIAL AND METHODS

Sixty MTC patients with persistent or recurrent hypercalcitonemia (n=49), a characteristic general symptom (diarrhea, n=4) or a normal basal calcitonin level without general symptoms (n=7) were investigated by dynamic liver CT, MRI and angiography between 06/1998 and 06/2002.

RESULTS

Dual-phase CT and MRI investigations identified hepatic metastases with relatively low frequency (8/58 on MRI, and 7/60 on CT). Angiography indicated liver involvement in 54/60 cases. The hepatic metastases were typically multiple, hypervascular, small foci (only 13 foci measured >/=10 mm). With one exception significant disease progression was not observed over 5 years of follow-up.

CONCLUSIONS

Liver angiography is a powerful tool to reveal hepatic metastases in MTC patients. Frequent, inoperable liver metastases in hypercalcitoninemic MTC patients demonstrate that secondary lymph node dissection is an inefficient technique for restoration of a normal calcitonin level.

Medullary thyroid carcinoma: results of a standardized surgical approach in a contemporary series of 80 consecutive patients

BACKGROUND

The surgical management and follow-up strategy in patients with medullary thyroid carcinoma (MTC) remain controversial because of the lack of data on the natural history of these tumors and their patterns of progression.

METHODS

We reviewed the records of all patients who underwent a cervical operation for MTC between 1991 and 2002. Compartment-oriented surgery (COS) was performed to minimize the risk of cervical recurrence.

RESULTS

We identified 92 consecutive patients who underwent a cervical operation for MTC: 80 had invasive MTC, and 12 had C-cell hyperplasia after prophylactic thyroidectomy for familial MTC. Ten (13%) of the 80 patients with invasive MTC presented with distant metastases and underwent COS to achieve local-regional control; cervical recurrence developed in none, but three have died of MTC. The remaining 70 patients underwent COS for primary (n=23) or recurrent (n=47) MTC. Disease recurred in 18 (26%) of these 70 patients at a median follow-up of 35 months, with 10 (14%) of the recurrences being cervical. Recurrent disease was associated with a basal calcitonin level of >250 pg/mL in all but four patients, two of whom showed tumor dedifferentiation. In contrast, only 5 (11%) patients without evidence of recurrence had basal calcitonin levels of >250 pg/mL at last follow-up.

CONCLUSIONS

Complete COS minimizes cervical recurrence. Radiographic evidence of recurrent disease is unlikely when the calcitonin level is < or =250 pg/mL. These data could be used to develop a logical, cost-effective treatment and follow-up strategy for patients with MTC.

Impact of modified radical neck dissection on biochemical cure in medullary thyroid carcinomas

BACKGROUND

This study evaluated the outcome of total thyroidectomy and modified radical neck dissection in primary treatment of patients with medullary thyroid carcinoma (MTC).

METHODS

Thirty-six patients with sporadic (n = 16) and hereditary (n = 20) MTC underwent thyroidectomy and systematic central and lateral lymph node dissection (unilateral, 23; bilateral, 13) between 1994 and 2000. Postoperative serum calcitonin levels were correlated with immediate or delayed surgery, tumor categories, and lymph node metastases.

RESULTS

Sixteen of 36 (44%) patients with clinically evident MTC treated with central and lateral neck dissection exhibited normal basal and stimulated calcitonin levels at a median follow-up of 3.7 years. Lymph node involvement was detected in 75% of these patients and correlated with the TNM stages. Biochemical cure was achieved according to the T categories in 83% of the patients in stage T1, 42% in stage T2, and none of the patients in stage T4 (P = .011). Basal and stimulated calcitonin levels were found to be normal in 89% of the patients without lymph node involvement and in 30% of the patients with lymph node metastases (P = .005).

CONCLUSIONS

Screening for MTC and primary treatment with total thyroidectomy and modified radical neck dissection are essential for biochemical cure of MTC.

Current approaches and perspectives in the therapy of medullary thyroid carcinoma

BACKGROUND

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor derived from parafollicular cells. At present, surgery is the most important treatment for MTC.

METHODS

We describe the current approaches of MTC treatment (surgery, chemotherapy, radiation therapy, and biologic therapy).

RESULTS

MTC is currently approached surgically in the main part through total thyroidectomy and compartment-oriented microdissection of cervicomediastinal lymph nodes. Substitutive l-thyroxine administration together with close clinical monitoring and the measurement of basal and stimulated serum calcitonin are subsequently performed. Radiotherapy and chemotherapy play a marginal role in advanced MTC. Recently, it has been found that somatostatin analogs and type I interferon are able to control the neuroendocrine symptoms induced by advanced MTC and that they provide clinical benefit by improving the lifestyle of these patients.

CONCLUSION

Although these agents are poorly active in inducing a shrinkage in tumor mass, the combined use of different biologic agents and cytotoxic drugs needs to be explored in advanced MTC. However, at present, surgery is the only curative treatment for MTC.

Surgical strategy for the treatment of medullary thyroid carcinoma

OBJECTIVE

To evaluate surgical complications, patterns of lymph node metastases, and calcitonin response to compartment-oriented lymphadenectomy in patients with primary or recurrent medullary thyroid carcinoma (MTC).

SUMMARY BACKGROUND DATA

The majority of patients with invasive MTC have metastasis to regional lymph nodes at the time of diagnosis, as evidenced by the frequent finding of persistently elevated calcitonin levels after thyroidectomy and the high rates of recurrence in the cervical lymph nodes reported in retrospective studies. These data have provided the rationale for surgeons to perform a more extensive lymphadenectomy at the time of initial thyroidectomy and to consider reoperative cervical lymphadenectomy in patients with persistently elevated calcitonin levels after thyroidectomy.

METHODS

Forty patients underwent surgery for MTC from 1991 to 1997 (23 sporadic cases, 17 familial cases). Patients were divided into three groups based on whether they had undergone previous thyroidectomy and on the results of standardized staging studies performed after referral to the authors' institution. Group 1 (11 patients) had received no previous surgery; group 2 (13) underwent thyroidectomy before referral and had an elevated calcitonin level without radiologic evidence of local regional or distant metastases; and group 3 (16) underwent thyroidectomy before referral and had an elevated calcitonin level with radiologic evidence of local-regional recurrence. The central neck compartment was dissected in all patients; preoperative staging and the extent of previous surgery dictated the need for lateral (modified radical) neck dissection. After primary or reoperative surgery, calcitonin levels were assessed.

RESULTS

All patients had major reductions in postoperative calcitonin levels. Seven (29%) of 24 patients in groups 1 and 2 achieved normal calcitonin values compared with only 1 (6%) of 16 in group 3. Postoperative complications included seven cases (17%) of permanent hypoparathyroidism; five (71%) of these occurred in group 3. There were no iatrogenic recurrent laryngeal nerve injuries; one patient required recurrent nerve resection to achieve complete tumor extirpation. At a median follow up of 35 months, local recurrence was documented in 5 (13%) of 40 patients.

CONCLUSIONS

Compartment-oriented lymphadenectomy performed early in the course of MTC is safe and may return calcitonin levels to normal in up to 25% of carefully selected patients. However, reoperation for bulky cervical disease (group 3) rarely results in normal calcitonin levels and is associated with a high incidence of permanent hypoparathyroidism.

The surgical treatment of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a unique disease in solid tumor oncology due to its ability to secrete calcitonin (iCT), a highly sensitive and specific serum marker of persistent or recurrent disease even at a microscopic level. The relatively long duration of survival experienced by most patients with MTC combined with the visible nature of surgical complications, when they occur, has caused most surgeons to take a conservative approach to the operative management and follow-up of patients with MTC. In contrast, the patient, family physician, and endocrinologist watch the iCT slowly rise, indicative of persistent and usually progressive invasive cancer. Amidst this clinical dilemma, we developed a standardized diagnostic and operative strategy to maximize local-regional tumor control and facilitate patient management.

Thyroid carcinoma

During the past years advances have been made in the understanding of the molecular mechanisms involved in the initiation and progression of thyroid carcinoma. Mutations in tumor suppressor genes such as p53 and oncogenes such as N-ras may be important for progression of well-differentiated thyroid carcinomas. Activation of the ret protooncogene located on chromosomal region 10q11.2 has been identified as a key factor in the initiation of papillary and medullary carcinoma. Integration of these discoveries into a prognostic classification scheme may allow us to better predict the biologic behavior of tumors in individual patients. Despite the recent advances in our understanding of the molecular events occurring during thyroid carcinogenesis, major questions persist regarding aspects of patient management. New diagnostic modalities may enable us to noninvasively discriminate between benign and malignant thyroid nodules, and to detect recurrent disease earlier. Although the optimal surgical procedure for well-encapsulated tumors is still debated, recent clinical studies have shown that for those patients with tumors > 1.5 cm, the routine use of RAI and hormone suppression can improve local control and survival rates. Findings in two recent reviews suggest that patients with widely invasive thyroid masses benefit from the surgical removal of all gross tumor. Further investigation is required to define the role of adjuvant radiotherapy and the most appropriate management of unresectable disease. Incorporation of prognostic markers into clinical staging systems should allow surgeons to better tailor their treatment plans for each patient. Translation of recent basic science advances into the clinical arena may also aid in the development of novel treatment strategies for patients with aggressive tumors.