Multivariate analysis of patients with medullary thyroid carcinoma. Prognostic significance and impact on treatment of clinical and pathologic variables

Minimal residual disease in thyroid carcinoma

The detection of disseminated tumor cells in differentiated (DTC) and medullary thyroid carcinomas (MTC) is one of the main topics in current thyroid cancer research. Immunocytochemistry and polymerase chain reaction (PCR) provide the tools for the identification of a small number of thyroid cancer cells in peripheral blood and cervical lymph nodes. Thyroid-specific markers, such as thyroglobulin (Tg) mRNA and thyroid peroxidase (TPO) mRNA, have been detected with RT-PCR in blood samples of tumor patients and healthy control subjects. To prevent false-positive results, quantitative PCR systems were established. Tumor-specific markers, such as telomerase activity and cytokeratin 20 (CK20), have been detected in various epithelial tumors. Amplification products of these markers were found in blood samples and in fine-needle aspiration (FNA) biopsies of patients with thyroid carcinomas. Using molecular detection of disseminated tumor cells in cervical lymph nodes with CK20 RT-PCR, a higher percentage of involved lymph nodes was detected compared to immunohistochemistry. The results of the presented studies may help researchers to develop more sensitive methods for early tumor cell dissemination, and refine risk groups that might benefit from more extensive surgical procedures or adjuvant therapy. However, the prognostic value of minimal residual disease (MRD) in thyroid carcinoma has to be confirmed in large or multicenter prospective studies.

Thyroid cancer

Four types of thyroid cancer comprise more than 98% of all thyroid malignancies. Papillary thyroid carcinoma (PTC) may have a very benign course while undifferentiated thyroid carcinoma (UTC) belongs to the most aggressive human malignancies. A variety of genes have been identified to be involved in the pathogenesis of thyroid carcinoma. Somatic Ras mutations seem to be an early event and are frequently found in follicular thyroid carcinomas. Somatic rearrangements of RET and TRK are almost exclusively found in PTC and may be found in early stages. Germline RET missense mutations lead to hereditary medullary thyroid carcinoma (MTC). In contrast, the significance of somatic RET mutations in sporadic MTC is unknown. p53 seems to play a crucial role in the dedifferentiation process of thyroid carcinoma. The precise role of PTEN remains to be elucidated. The only clearly identified exogenous factor that may lead to thyroid carcinoma (mainly PTC) is radiation. Of interest, radiation is capable to induce RET rearrangements. In general, early diagnosis is mandatory to enable the chance of cure. Surgery is the treatment of choice. Depending on the tumour type, surgery in combination with either radioiodine, external radiation or chemotherapy often enables the control of local tumour burden. In MTC and UTC, once thyroid cancer is spread to distant organs, efficacious therapeutic agents are almost non-existing. However, our growing knowledge of genes involved in thyroidal oncogenesis may contribute to the development of more effective treatment modalities. Some preliminary data on gene therapy are quite promising.

Thyroid carcinoma invading the cervicovisceral axis: routes of invasion and clinical implications

BACKGROUND

Controversy exists about the routes of invasion (extrathyroidal versus lymphogenic extension) when differentiated carcinoma (DTC) and medullary thyroid carcinoma (MTC) invade the cervicovisceral axis (ie, larynx, trachea, esophagus).

METHODS

We carried out an institutional analysis, from November 1994 to October 1999, of 451 consecutive patients undergoing surgery for DTC and MTC.

RESULTS

Irrespective of tumor entity, carcinomas with cervicovisceral invasion (n = 34) were significantly larger and displayed higher pT categories (mainly pT4) than noninvasive carcinomas. In invasive papillary thyroid carcinoma (PTC) and MTC, the rates of positive lymph nodes were significantly higher than in noninvasive controls. When separate logistic regression analyses were fitted for laryngeal, tracheal, and esophageal invasion, extrathyroidal growth (pT4) consistently was a significant factor predictive of invasion in both DTC and MTC, with relative risks of 10.9 to 67.8. As the routes of invasion are similar in DTC and MTC, all data were pooled for multivariate analyses. Herein, the pN1 category had a significant impact only on esophageal invasion, with a relative risk of 4.7.

CONCLUSIONS

Invasion of the cervicovisceral axis is more often caused by extrathyroidal growth than by nodal metastasis. To keep nodal metastasis from encroaching onto the cervicovisceral axis, paratracheal and paraesophageal lymph nodes should be cleared from the cervicocentral compartment at the primary operation.

Normal preoperative calcitonin levels do not always exclude medullary thyroid carcinoma in patients with large palpable thyroid masses

Medullary thyroid carcinoma (MCT) is a sporadic or familial tumor of the parafollicular or C-cells that secretes calcitonin. The sporadic form usually presents with a palpable thyroid nodule or cervical adenopathy, by which time basal calcitonin levels are almost always elevated. Without special stains, fine-needle biopsy may fail to detect MCT. Recently, several investigators have recommended routine measurement of serum calcitonin in patients with nodular thyroid diseases for the preoperative diagnosis of MCT. A 31-year-old woman had a large palpable MCT with normal calcitonin and carcinoembryonic antigen levels before surgery. Fine-needle aspiration (FNA) demonstrated atypical cells but was not diagnostic of MCT. Pathology revealed a 3 x 4.5 x 2.3 cm MCT. Immunochemical stains showed immunoreactivity for calcitonin and synaptophysin, but no immunoreactivity to thyroglobulin. Postoperative basal and pentagastrin-stimulated calcitonin levels have remained undetectable without evidence of recurrent cancer. We have evaluated six other patients with MCT that were palpable. They had preoperative calcitonin levels ranging from 322-50,032 pmol/L. This unique case of a woman with a 4.5-cm MCT and normal preoperative calcitonin levels, emphasizes the need for careful clinical evaluation and FNA biopsy in managing patients with nodular thyroid disease.

Medullary thyroid carcinoma: clinical characteristics, treatment, prognostic factors, and a comparison of staging systems

BACKGROUND

The clinical courses of patients with medullary thyroid carcinoma (MTC) vary, and a number of prognostic factors have been studied, but the significance of some of these factors remains controversial.

METHODS

The study group consisted of 104 patients with MTC or C-cell hyperplasia managed at the hospitals of the University of California, San Francisco, between January 1960 and December 1998. Patients were classified as having sporadic MTC, familial non-multiple endocrine neoplasia (MEN) MTC, MEN 2A, or MEN 2B. The TNM, European Organization for Research and Treatment of Cancer (EORTC), National Thyroid Cancer Treatment Cooperative Study (NTCTCS), and Surveillance, Epidemiology, and End Results (SEER) extent-of-disease stages were determined for each patient. The predictive values of these staging or prognostic scoring systems were compared by calculating the proportion of variance explained (PVE) for each system.

RESULTS

Fifty-six percent of the patients had sporadic MTC, 22% had familial MTC, 15% had MEN 2A, and 7% had MEN 2B. The overall average age at diagnosis was 38 years, and patients with sporadic MTC presented at an older age (P < 0.05). Thirty-two percent of the patients with hereditary MTC were diagnosed by screening (genetic and/or biochemical). These patients had a lower incidence of cervical lymph node metastasis (P < 0.05) and 94.7% were cured at last follow-up (P < 0.0001) compared with patients not screened. Patients with sporadic MTC who had systemic symptoms (diarrhea, bone pain, or flushing) had widely metastatic MTC and 33.3% of those patients died within 5 years. Overall, 49.4% of the patients were cured, 12.3% had recurrent MTC, and 38.3% had persistent MTC. The mean follow-up time was 8.6 years (median, 5.0 years) with 10.7% (n=11) and 13.5% (n=14) cause specific mortality at 5 and 10 years, respectively. Patients with persistent or recurrent MTC who died of MTC lived for an average of 3.6 years (ranging from 1 month to 23.7 years). Patients who had total or subtotal thyroidectomy were less likely to have persistent or recurrent MTC (P < 0.05), and patients who had total thyroidectomy with cervical lymph node clearance required fewer reoperations for persistent or recurrent MTC (P < 0.05) than patients who underwent lesser procedures. In univariate analysis, age, gender, clinical presentation, TNM stage, sporadic/hereditary MTC, distant metastasis, and extent of thyroidectomy were significant prognostic factors. Only age and stage, however, remained independent prognostic factors in multivariate analysis. The TNM, EORTC, NTCTCS, and SEER staging systems were all accurate predictors of survival, but the EORTC prognostic scoring system had the highest PVE in this cohort.

CONCLUSIONS

Screening for MTC and early treatment (total thyroidectomy with central neck lymph node clearance) had nearly a 100% cure rate. Patients with postoperative hypercalcitoninemia without clinical or radiologic evidence of residual tumor after apparently curative surgery may enjoy long term survival but have occult MTC. Only patient age at presentation and TNM stage were independent predictors of survival. The EORTC criteria, which included the greatest number of significant prognostic factors in our cohort, had the highest predictive value.

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.

Occult sporadic medullary microcarcinoma with lymph node metastases

A sporadic form of medullary occult microcarcinoma was cytologically diagnosed, by fine-needle aspiration biopsy (FNAB), on metastatic cervical lymph nodes. The cytologic specimens were partially smeared and partially zinc-formalin-fixed, so that a microinclusion clot for immunohistochemical studies would be possible. The reactivity to calcitonin of neoplastic cells obtained from metastatic cervical lymph nodes supported the search for a thyroid tumor, which only a careful echographic study revealed. Under sonographic guidance, FNAB on a 0.5-cm hypoechoid nodule was performed. The smears were diagnostic of medullary carcinoma. A total thyroidectomy with node dissection was made. Diagn. Cytopathol. 1999;21:203-206.

Medullary thyroid microcarcinoma: a clinicopathologic retrospective study of 38 patients with no prior familial disease

Thirty-eight patients (25 women, 13 men; mean age, 57.8 [32 to 91]) showing one or more medullary thyroid microcarcinomas (ie, < 1 cm), with no prior MEN II or medullary thyroid carcinoma history in their family, were reviewed. Follow-up was available for 29 patients (mean, 53.6 months [1 to 147]). 21 patients (72.4%) are alive and free of disease, four patients (13.8%) died during follow-up without disease, 2 patients are alive with disease (local recurrence and persistent hypercalcitoninemia) after 80 and 99 months, respectively, and 2 patients died of disease after 24 and 46 months. Most tumors were incidental pathological findings (19 of 38) or were discovered by systematic blood calcitonin measurement for a nodular thyroid disease (15 of 38). Only the four patients who had an unfavorable outcome were symptomatic cases (palpable micro-MTC, diarrhea, cervical lymph node metastasis and pulmonary metastatic disease). The two patients with metastatic disease at diagnosis died during follow-up. In univariate analysis, a symptomatic medullary thyroid carcinoma was a strong predictor of an unfavourable outcome (p < .00008), as were the preoperative calcitonin level (P = .007) and an elevated postoperative calcitonin level (P = .004). Among 30 histopathological criteria, only the presence of amyloid correlated with an unfavorable outcome (P = .018).

[Medullary cancer of the thyroid]

INTRODUCTION

Medullary thyroid carcinoma is a rare disease which originates from the secretion of calcitonin by thyroid parafollicular cells. Sporadic (75%) and inherited (25%) forms of the disease are encountered. Familial forms (termed multiple endocrine neoplasia type IIa, IIb, or familial medullary thyroid carcinoma) may or may not be associated with other endocrinopathies such as pheochromocytoma and/or hyperparathyroidism.

CURRENT KNOWLEDGE AND KEY POINTS

Circulating forms of calcitonin, a marker of the disease, are heterogeneous in blood, thus explaining why assays lead to different results according to the method used.

FUTURE PROSPECT AND PROJECTS

Family screening is much easier, as germ line mutations of the proto-oncogene RET have recently been identified in inherited forms of the disease. Treatment includes extensive surgery. This, and prophylactic thyroidectomy in gene carriers, is discussed. Prognosis is much better nowadays, but precise follow-up has to be instituted.

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.

Medullary thyroid carcinoma: search for histological predictors of survival (109 proband cases analysis)

A group of 13 pathologists belonging to the French Calcitonin Tumor Study Group (GETC: Groupe d'Etude des Tumeurs à Calcitonine) examined the histological slides and medical records of 109 proband cases of medullary thyroid carcinoma (MTC) diagnosed on clinical features. The cases belonged to the various forms of the disease (80 sporadic and 29 familial MTC). The aim of the study was to detect histological predictors for survival by comparing morphological data from patients killed by the disease versus the others. Twenty-seven histological parameters were considered, including cellular heterogeneity, shape of the cells, and cytoplasmic characteristics. Other parameters such as sex, age, and phenotype of the disease were also studied. First, predictive parameters of interest on survival function were selected by univariate analysis (Mantel-Cox test). Then, the extracted parameters were tested in a multifactorial analysis using the Cox's forward stepping proportional hazard model. Five parameters were significantly associated with a lower survival function: presence of necrosis in the tumor (P = .001), squamous pattern (P = .002), age over 45 years (P = .004), presence of oxyphil cells in the tumor and absence of cells with intermediate cytoplasm (P = .025), less than 50% of calcitonin immunoreactive cells in the tumor (P = .04).

Pulmonary metastases of endocrine origin: the role of surgery

PURPOSE

To determine the clinical course and outcome of patients undergoing pulmonary resection for metastatic endocrine tumors.

METHODS

Retrospective review of 47 patients with known endocrine tumors and pulmonary metastases who were evaluated for surgical resection between 1975 and 1996.

RESULTS

Tumors evaluated included the following: carcinoid (16), thyroid (12), pancreatic adenocarcinoma (10), adrenocortical carcinoma (6), pheochromocytoma (2), and parathyroid (1). Thirty-three patients were asymptomatic. Hormone secretion was noted in five patients. Twenty-five patients, who had isolated lung metastases, good control of the primary tumor, and no medical contraindication had surgical resection. The number of pulmonary nodules was not a limiting factor as long as all disease could be resected with adequate residual pulmonary function. CT was successful in directing resection in all patients. Twenty-six operations were performed in 25 patients and 22 patients were treated medically. Wedge resection was performed for lesions <2 cm (15), and lobectomy for larger or multiple nodules (10). Four patients had bilateral nodules resected. There was no operative mortality and no major complications. Actuarial 5-year survival was 61% for surgically treated patients. Independent predictors of poor survival included positive mediastinal lymph nodes at time of surgery (p=0.004) and shorter disease-free interval (p=0.01). At a median of 6.7+/-1.2 years, six patients have developed radiographic appearance of a recurrence. A single patient with recurrent Hürthle cell cancer has had a successful reresection. The remaining patients have received chemotherapy. No patient with pancreatic carcinoma or adrenocortical carcinoma was a candidate for resection. All medically treated patients died within 6 months.

CONCLUSION

Patients with endocrine tumors and pulmonary metastases are usually asymptomatic, their conditions are diagnosed accurately with CT, and they can achieve long-term survival comparable to other tumors (sarcoma) after pulmonary metastasectomy.

CLINICAL IMPLICATIONS

Patients with carcinoid, thyroid, pheochromocytoma, and parathyroid tumors with pulmonary metastases should undergo surgical resection if there is the following: (1) no evidence of extrathoracic disease; (2) good control of the primary tumor; (3) no medical contraindications for surgery; and (4) pulmonary function that can tolerate resection of all documented disease. The role of adjuvant chemotherapy in patients with positive lymph nodes needs further study.

Argyrophilia and chromogranin A and B immunostaining in patients with sporadic medullary thyroid carcinoma. A critical appraisal of their prognostic utility

The purpose of the present study was to evaluate the prognostic utility of tumour argyrophilia and chromogranin A (CgA) and B (CgB) immunocytochemical expression in patients with sporadic medullary thyroid carcinoma. To this end, the histo-immunocytochemical data on a consecutive series of 99 such tumours were submitted to statistical analysis. In univariate analysis, a significantly increased risk of disease progression and death was present in patients with CgA-poor and CgB-poor tumours, respectively. Multivariate analyses were performed by adding the histo-immunocytochemical variables to the final (reference) models obtained in earlier work on the same case series, in which 18 clinicopathological variables had been taken into account. This addition did not change the prognostic impact of the variables considered in the two reference models; it did, however, increase the prognostic information for overall survival, since the adjunctive contribution of CgB immunocytochemical expression (as assessed by the likelihood ratio test) was statistically significant. It is concluded that the chromogranin B immunostaining pattern of the primary tumour allows the distinction of patients with an increased risk of death. Argyrophilia and expression of chromogranin A seem instead to be of no prognostic value in patients with sporadic medullary thyroid carcinoma.

Prognostic factors for survival and for biochemical cure in medullary thyroid carcinoma: results in 899 patients. The GETC Study Group. Groupe d'étude des tumeurs à calcitonine

BACKGROUND

Prognostic factors of sporadic or inherited medullary thyroid carcinoma (MTC) are still controversial and have been assessed in old and small series. A better knowledge of these factors would improve patient management.

OBJECTIVE

To evaluate factors involved in the prognosis of MTC in a large series of cases, using uni- and multivariate analysis.

DESIGN AND PATIENTS

Clinical, biological, surgical and epidemiological data on 899 MTC patients, diagnosed between 1952 and 1996, were collected by the French Calcitonin Tumors Study Group (GETC) with a standardized questionnaire, and processed in a national database.

MEASUREMENTS

Survival and biochemical cure (i.e. normal basal post-operative serum calcitonin levels) were analysed with Kaplan and Meier and log-rank test statistical procedures. Data are presented as adjusted rather than observed survival, to consider only patients who died of MTC. Cox's forward-stepping proportional hazard model was used to analyse factors with a significant influence on survival by univariate analysis.

RESULTS

Apart from the large proportion of familial forms (43%), the general characteristics of our population were similar to those in other studies: mean age at surgery = 43.4 years; sex ratio = 1 male/1.35 female; stage I = 20.8%; stage II = 21.2%; stage III = 46.5% and stage IV = 11.5%. 863 (96%) patients underwent surgery; 43% of operated patients were biochemically cured. Adjusted survival was 85.7 +/- 1.5% at 5 years and 78.4 +/- 2.1% at 10 years. Multivariate analysis showed that age and stage were independent predictive factors of survival. Gender, type of surgery, type of familial form were predictive only in univariate analysis. Biochemical cure predicts a survival rate of 97.7% at 10 years. Authentic recurrence, that is subsequent elevation of calcitonin (CT) after post-operative normalization, was found in 4.9%. In non-cured patients (57%), survival was still good: 80.2% (+/- 2.2%) and 70.3% (+/- 2.9%) at 5 and 10 years, respectively. Similarly, prediction of biochemical cure was solely dependent on stage.

CONCLUSION

Survival of these medullary thyroid carcinoma patients appears better than expected even in non-cured patients. Considering the strong impact of stage, the necessity for pre-operative diagnosis of MTC is obvious.

Reoperation in metastasizing medullary thyroid carcinoma: is a tumor stage-oriented approach justified?

BACKGROUND

Lymph node metastases (LNM) are very often found in medullary thyroid carcinoma. After primary therapy, elevated levels of calcitonin are measurable in many patients. Because of the low sensitivity and specificity of diagnostic tools to detect micrometastases, the question remains whether an extended lymphadenectomy improves the chance of cure and whether this approach should be tumor stage oriented.

METHODS

We analyzed the results of 36 patients with medullary thyroid carcinoma consecutively reoperated from 1988 to 1996, performing microdissection of all four locoregional lymph node compartments.

RESULTS

Pathologic tumor stage (pT) category was classified as pT1, n = 3; pT2 n = 22; pT3, n = 6; and pT4, n = 5. LNM were found in 34 patients (94%). The cervicocentral compartment contained LNM in 85%, the cervicolateral compartments in 41% to 54%, and the upper mediastinum in 36%. Patients with different pT category did not differ in the rate of LNM. Ipsilateral cervicolateral LNM were found in 50% to 71% and contralateral cervicolateral LNM in 14% to 40%. Nine (35%) of 26 patients without distant metastases were biochemically cured. In 10 patients (38%) calcitonin level decreased more than 50%.

CONCLUSIONS

LNM were almost always (94%) found in patients who have elevated calcitonin levels after primary therapy. In patients without distant metastases, four-compartment lymphadenectomy gives a chance of cure in 35%. A tumor stage-oriented approach does not seem to be justified.