Quantitative assessment of promoter methylation profiles in thyroid neoplasms.

CONTEXT: Cancer-specific molecular markers are needed to supplement the cytopathological assessment of thyroid tumors, because a majority of patients with cytologically indeterminate nodules currently undergo thyroidectomy without a definitive diagnosis. OBJECTIVE: The aim of this study was the quantitative assessment of promoter hypermethylation and its relation to the BRAF mutation in thyroid tumors. DESIGN: Quantitative hypermethylation of Rassf1A, TSHR, RAR-beta2, DAPK, S100, p16, CDH1, CALCA, TIMP3, TGF-beta, and GSTpi was tested on a cohort of 82 benign and malignant thyroid tumors and five thyroid cancer cell lines. SETTING: The study was conducted at a tertiary research hospital. PATIENTS: Patients underwent surgical resection for a thyroid tumor from 2000 to 2003 at our institution. INTERVENTIONS: There were no interventions. MAIN OUTCOME MEASURE: Final surgical pathology diagnosis was the main outcome measure. RESULTS: Thyroid tumors showed hypermethylation for the following markers: Rassf1A, TSHR, RAR-beta2, DAPK, CDH1, TIMP3, and TGF-beta. A trend toward multiple hypermethylation was evident in cancer tissues, with hypermethylation of two or more markers detectable in 25% of hyperplasias, 38% of adenomas, 48% of thyroid cancers, and 100% of cell lines. A rank correlation analysis of marker hypermethylation suggests that a subset of these markers is epigenetically modified in concert, which may reflect an organ-specific regulation process. Furthermore, a positive correlation was found between the BRAF mutation and RAR-beta2, and a negative correlation was found between the BRAF mutation and Rassf1A. CONCLUSIONS: Methylation-induced gene silencing appears to affect multiple genes in thyroid tissue and increases with cancer progression. Additional markers with better discriminatory power between benign and malignant samples are needed for the diagnostic assessment of cytologically indeterminate thyroid nodules.

Randomized prospective evaluation of frozen-section analysis for follicular neoplasms of the thyroid.

OBJECTIVE: To evaluate the clinical utility of frozen section in patients with follicular neoplasms of the thyroid in a randomized prospective trial. SUMMARY BACKGROUND DATA: The finding of a follicular neoplasm on fine-needle aspiration prompts many surgeons to perform intraoperative frozen section during thyroid lobectomy. However, the focal distribution of key diagnostic features of malignancy contributes to a high rate of noninformative frozen sections. METHODS: The series comprised 68 consecutive patients with a solitary thyroid nodule in whom fine-needle aspiration showed a follicular neoplasm. Patients were excluded for bilateral or nodal disease, extrathyroidal extension, or a definitive fine-needle aspiration diagnosis. Final pathologic findings were compared with frozen sections, and cost analyses were performed. RESULTS: Sixty-one patients met the inclusion criteria. Twenty-nine were randomized to the frozen-section group and 32 to the non-frozen-section group. In the non-frozen-section group, one patient was excluded when gross examination of the specimen was suggestive of malignancy and a directed frozen section was diagnostic of follicular carcinoma. Frozen-section analysis rendered a definitive diagnosis of malignancy in 1 of 29 (3.4%) patients, who then underwent a one-stage total thyroidectomy. In the remaining 28 patients, frozen section showed a "follicular or Hürthle cell neoplasm." Permanent histology demonstrated well-differentiated thyroid cancer in 6 of these 28 patients (21%). Of the 31 patients in the non-frozen-section group, 3 (10%) showed well-differentiated thyroid carcinoma on permanent histology. Complications were limited to one transient unilateral vocal cord dysfunction. All but one patient had a 1-day hospital stay. There were no significant differences between the groups in surgical time or total hospital charges; however, the charge per informative frozen section was approximately $12,470. CONCLUSIONS: For the vast majority of patients (96.4%) with follicular neoplasms of the thyroid, frozen section is neither informative nor cost-effective.

Mandatory second opinion surgical pathology at a large referral hospital.

BACKGROUND: When patients are referred to one's own institution for therapy based on a histopathologic diagnosis rendered at another institution, many hospitals require a second opinion of the surgical pathology material. This quality assurance practice has been threatened in the era of managed care and cost containment. METHODS: The authors reviewed the impact of mandatory second opinion surgical pathology at The Johns Hopkins Hospital. Cases were collected prospectively over a 21-month period from April 1995 to December 1996. For the purposes of this study, a changed diagnosis was defined as a discordant diagnosis resulting in a major modification in therapy or prognosis. The majority of cases involved a change between benign and malignant or a major change in tumor classification. Changes involving a modification of tumor grade or stage were not included. RESULTS: Of 6171 cases reviewed, second opinion surgical pathology resulted in 86 changed diagnoses (1.4%). Compared with the entire group, 2 organ systems were significantly more likely to undergo a change in diagnosis: serosal surfaces (9. 5%) (P < 0.0001) and the female reproductive tract (5.1%) (P < 0. 0001). Organ systems that were not more likely to undergo a change in diagnosis than the group as a whole included the skin (2.9%); central nervous system (2.8%); breast (1.4%); genitourinary system (1.2%); gastrointestinal tract (1.2%); hematologic system (1.1%); ear, nose, and throat (1.0%); bone/soft tissue (0.9%); lung (0.6%); endocrine (0%); mediastinum (0%); and cardiovascular system (0%). CONCLUSIONS: Second opinion surgical pathology can result in major therapeutic and prognostic modifications for patients sent to large referral hospitals. Although the overall percentage of affected cases is not large, the consistent rate of discrepant diagnosis uncovered by second opinion surgical pathology may have an enormous human and financial impact. Accordingly, the authors recommend that review of the original histologic material should be undertaken prior to the institution of a major therapeutic endeavor.

Second esophageal tumors in patients with head and neck squamous cell carcinoma: an assessment of clonal relationships.

Patients with squamous cell carcinoma of the head and neck (HNSCC) often develop second carcinomas elsewhere in the upper aerodigestive tract. Some of these paired tumors share a common origin, reflecting the ability of a single progenitor cell to replicate, expand, and populate contiguous regions of the upper aerodigestive tract-a process referred to as clonal expansion. The geographical limitations of clonal expansion, however, have not been adequately addressed. For example, it is not known whether a neoplastic clone from the oral cavity, pharynx, or larynx can migrate to the esophagus. We compared paired tumors from 16 patients with HNSCC and a second squamous cell carcinoma of the esophagus (ESCC) for patterns of allelic loss on chromosomal arms 3p, 9p, and 17p. Losses at these loci occur early during neoplastic transformation of the respiratory tract. In 14 cases (87%), the paired tumors had discordant patterns of allelic loss, suggesting that these tumors were not clonally related. Conversely, two (13%) of the 16 paired tumors had identical genetic alterations, which suggests clonal expansion as the mechanism underlying tumor multifocality. One clone spread from the hypopharynx into the cervical esophagus, and the other spread from the tonsil to the distal esophagus. Although most second ESCCs appear to arise as independent neoplasms, a clonal population of neoplastic cells is capable of traveling across substantial distances to give rise to second tumors at different anatomical sites.

Telomerase activity: a marker to distinguish follicular thyroid adenoma from carcinoma.

The inability to distinguish microinvasive follicular thyroid cancer from benign follicular tumors preoperatively presents an important surgical dilemma. We examined 44 follicular tumors and found telomerase activity in all 11 follicular carcinomas and in 8 of 33 benign follicular tumors. It was undetectable in 22 normal thyroid tissues adjacent to the tumors. Telomerase activity may thus provide a diagnostic marker distinguishing benign from malignant follicular thyroid tumors. The ability to identify invasive follicular thyroid tumors could avert over 14,000 thyroidectomies annually in the United States, thereby significantly decreasing morbidity and health care costs.