Anaplastic Thyroid Cancer in Sicily: The Role of Environmental Characteristics

BACKGROUND

Anaplastic thyroid cancer (ATC) is a rare but extremely aggressive cancer of the thyroid, contributing up to 30-40% of thyroid cancer-specific mortality. We analyzed ATC characteristics and survival rates in Sicily to evaluate the possible influence of environmental factors. With this aim, data regarding ATC incidences in urban/rural and industrial, iodine-deficient, and volcanic vs control areas were compared in Sicily as well as ATC data from Sicily and USA.

METHODS

Using the Sicilian Register of Thyroid Cancer (SRTC) database incidence, age, gender, tumor size and histotype, extrathyroidal extension, stage, and coexistence with pre-existing differentiated thyroid cancer (DTC) were evaluated in different areas of Sicily and also compared with Surveillance Epidemiology and End Results data in USA.

RESULTS

Forty-three ATCs were identified in Sicily in the period 2002-2009. In our series only age <70 years at diagnosis (p = 0.01), coexistence with DTC (p = 0.027) and tumor size ≤6 cm (p = 0.012) were significant factors for increased survival at univariate analysis (only age at multivariate analysis). No difference in ATC incidence was found in urban vs rural areas and in iodine-deficient and industrial vs control areas. By contrast, in the volcanic area of Sicily, where DTC incidence is doubled relative to the rest of the island, also ATC incidence was increased. ATC data in Sicily were similar to those reported in the same period in the USA where overall survival rate at 6 and 12 months, however, was smaller.

CONCLUSION

The similar ATC data observed in Sicily and USA (having different genetic background and lifestyle) and the increased ATC incidence in the volcanic area of Sicily paralleling the increased incidence of papillary thyroid cancer are compatible with the possibility that casual additional mutations, more frequent in a background of increased cell replication like DCT, are the major causes of ATC rather than genetic background and/or direct environmental influences.

Papillary thyroid cancer: time course of recurrences during postsurgery surveillance

CONTEXT

The current use of life-long follow-up in patients with papillary thyroid cancer (PTC) is based largely on the study of individuals diagnosed and treated in the latter half of the 20th century when recurrence rates were approximately 20% and relapses detected up to 20-30 years after surgery. Since then, however, diagnosis, treatment, and postoperative monitoring of PTC patients have evolved significantly.

OBJECTIVES

The objective of the study was to identify times to PTC recurrence and rates by which these relapses occurred in a more recent patient cohort.

PATIENTS AND DESIGN

We retrospectively analyzed follow-up data for 1020 PTC patients consecutively diagnosed in 1990-2008 in 8 Italian hospital centers for thyroid disease. Patients underwent thyroidectomy, with or without radioiodine ablation of residual thyroid tissue and were followed up with periodic serum thyroglobulin assays and neck sonography.

RESULTS

At the initial posttreatment (≤ 12 months) examination, 948 patients had no structural/functional evidence of disease. During follow-up (5.1-20.4 years; median 10.4 years), recurrence (cervical lymph nodes, thyroid bed) was diagnosed in 13 (1.4%) of these patients. All relapses occurred 8 or fewer years after treatment (10 within the first 5 years, 6 within the first 3 years). Recurrence was unrelated to the use/omission of postoperative radioiodine ablation.

CONCLUSION

In PTC patients whose initial treatment produces disease remission (no structural evidence of disease), recurrent disease is rare, and it usually occurs during the early postoperative period. The picture of recurrence timing during the follow-up provides a foundation for the design of more cost-effective surveillance protocols for PTC patients.

Identification and optimal postsurgical follow-up of patients with very low-risk papillary thyroid microcarcinomas

CONTEXT

Most papillary thyroid microcarcinomas (PTMCs; ≤ 1 cm diameter) are indolent low-risk tumors, but some cases behave more aggressively. Controversies have thus arisen over the optimum postoperative surveillance of PTMC patients.

OBJECTIVES

We tested the hypothesis that clinical criteria could be used to identify PTMC patients with very low mortality/recurrence risks and attempted to define the best strategy for their management and long-term surveillance.

DESIGN

We retrospectively analyzed data from 312 consecutively diagnosed PTMC patients with T1N0M0 stage disease, no family history of thyroid cancer, no history of head-neck irradiation, unifocal PTMC, no extracapsular involvement, and classic papillary histotypes. Additional inclusion criteria were complete follow-up data from surgery to at least 5 yr after diagnosis. All 312 had undergone (near) total thyroidectomy [with radioactive iodine (RAI) remnant ablation in 137 (44%) - RAI group] and were followed up yearly with cervical ultrasonography and serum thyroglobulin, TSH, and thyroglobulin antibody assays.

RESULTS

During follow-up (5-23 yr, median 6.7 yr), there were no deaths due to thyroid cancer or reoperations. The first (6-12 months after surgery) and last postoperative cervical sonograms were negative in all cases. Final serum thyroglobulin levels were undetectable (<1 ng/ml) in all RAI patients and almost all (93%) of non-RAI patients.

CONCLUSION

Accurate risk stratification can allow safe follow-up of most PTMC patients with a less intensive, more cost-effective protocol. Cervical ultrasonography is the mainstay of this protocol, and negative findings at the first postoperative examination are highly predictive of positive outcomes.

Predictive value of recombinant human TSH stimulation and neck ultrasonography in differentiated thyroid cancer patients

BACKGROUND

Serum thyroglobulin (Tg) stimulation by recombinant human TSH (rhTSH), in combination with neck ultrasonography (US), is an important tool in the first follow-up of differentiated epithelial cell thyroid carcinoma (DTC) patients. The objective of this study was to investigate if a second rhTSH stimulation, performed 2-3 years later, is of clinical utility in the follow-up of these patients.

METHODS

One hundred and one consecutive ambulatory DTC patients were studied. The great majority of them (89/101) were low-risk patients, being stage I or II at tumor node metastasis (TNM) staging classification. All study patients had been treated by surgery and radioiodine ablation, and exhibited, at first rhTSH follow-up, either undetectable Tg (<or=1 ng/mL) (rhTSH1-Tg-, n = 89 patients considered as free of disease) or low Tg (>1-5 ng/mL) (rhTSH1-Tg+, n = 12 patients considered with uncertain prognosis), with no US evidence of residual disease. In all patients, serum Tg measurement after a second rhTSH stimulation and neck US were performed.

RESULTS

At the second follow-up, all 89 rhTSH1-Tg-patients showed a negative US, and Tg became low positive only in one case, whereas it remained undetectable in the other patients. The overall negative predictive value of rhTSH1-Tg- was, then, 98.9%. Out of the remaining 12 patients (i.e., rhTSH1-Tg+ patients), 2 showed disease persistence/recurrence (with a positive predictive value of rhTSH1-Tg+ of 16.7%) and 6 became Tg-.

CONCLUSIONS

A second rhTSH stimulation is useless in DTC patients who were rhTSH-Tg and imaging negative at first follow-up, while it is suggested in patients with detectable, although low, rhTSH-Tg levels at first follow-up: in the absence of clinical or US evidence of disease persistence, these patients should not be retreated by radioiodine, but simply scheduled for a later rhTSH stimulation.