The role of surgery in the management of differentiated thyroid cancer

Papillary thyroid carcinoma and familial adenomatous polyposis of the colon

OBJECTIVE

Case report and limited review of the literature on the topic of papillary thyroid carcinoma and familial adenomatous polyposis and its genetic associations.

METHODS

A patient with multiple prior surgeries for colonic polyps, abdominal perineal resection for colorectal cancer, and wedge resection for metastatic adenocarcinoma (consistent with rectal primary) presented with a thyroid mass. Fine-needle aspiration demonstrated papillary thyroid carcinoma.

RESULTS

The patient underwent total thyroidectomy. Pathologic examination revealed the cribriform-morular variant of papillary carcinoma that has been reported in patients with familial adenomatous polyposis.

CONCLUSIONS

Cribriform-morular variant of papillary thyroid carcinoma is an uncommon diagnosis known to be associated with familial adenomatous polyposis. Although the incidence is rare, this diagnosis should raise the clinician's suspicions to recommend both colorectal screening and genetic counseling for family members.

Management of patients with low-risk papillary thyroid carcinoma

OBJECTIVE

To define a rational, cost-effective, simple approach to managing most patients with papillary thyroid cancer (PTC) who are at low-risk of either cause-specific mortality or tumor recurrence.

METHODS

Taking advantage of the collective experience of a cohort of 2512 patients with PTC who had initial definitive treatment at the Mayo Clinic in Rochester, Minnesota, between 1940 and 2000, a 5-step approach to the management of low-risk PTC has been devised. This program is based on appropriate preoperative ultrasound localization of neck disease and potentially curative surgery consisting of near-total or total thyroidectomy, with appropriate neck nodal exploration and resection.

RESULTS

The emphasis of the present program is on the extent of initial surgery, where optimal care is ascribed to a near-total thyroidectomy with curative intent and appropriate neck nodal resection as predicated by appropriate preoperative ultrasonography evaluation of regional lymph nodes. Radioiodine remnant ablation (RRA) is not applicable to patients with PTC who are defined on the day of definitive initial surgery to be at low risk as defined by a metastasis, age, completeness of resection, invasion, and size (MACIS) score of less than 6.

CONCLUSION

The outlook for patients with low-risk PTC is very optimistic, with rates at 30 postoperative years of only 1% for cause-specific mortality and less than 15% for tumor recurrence at any site. The long-term results obtained by potentially curative bilateral resection, appropriate regional lymph nodal excision, and selective use of RRA are excellent. Realistically improving these acceptably low rates for cause-specific mortality and tumor recurrence may be difficult.

Gamma probe-guided surgery for revision thyroidectomy: in comparison with conventional technique

Reoperative thyroid surgery may be required in patients who undergo any procedure less than total or near total thyroidectomy. The aim of this study was to investigate advantages of gamma-probe guided revision thyroidectomy (GGRT) over conventional revision thyroidectomy (CRT) in patients with differentiated thyroid carcinoma (DTC). GGRT was assessed according to the TSH values, complication rates and the incidence of carcinoma in residual thyroid tissue. In this randomised prospective clinical trial, 25 patients with differentiated thyroid carcinoma who had previously undergone surgery for benign multinodular goiter were included in the study. GGRT was performed in 11 (44%) patients (Group 1) and CRT in 14 (65%) (Group 2). The intraoperative mean ratio of thyroid activity to background activity (T/B) was detected as 5.1 +/- 1.4 and the mean ratio of thyroid bed activity to background activity after excision (Tbed/B) was 1.3 +/- 0.3, (p < 0.01). Although the incidence of carcinoma in residual thyroid tissue was higher in group 1 (4/11) in comparison to group 2 (1/14), it was not statistically significant. The elevation of the TSH concentration at the first post-operative month was significantly higher in group 1 in comparison with group 2 (18 +/- 25 5 +/- 3 mlU/l), (p < 0.02). These results indicate that intraoperative gamma probe application may be beneficial to detect and remove residual thyroid tissue in revision thyroidectomy.

Importance of tumour size in papillary and follicular thyroid cancer

BACKGROUND

The most controversial change in the new pathological tumour node metastasis (pTNM) classification of thyroid tumours is the extension of the pT1 classification to include tumours up to 20 mm.

METHODS

Four hundred and three patients with pT1 or pT2 differentiated thyroid carcinomas were divided into three groups according to tumour diameter (group 1, 10 mm or less; group 2, 11-20 mm; group 3, 21-40 mm). They were analysed retrospectively with respect to carcinoma-specific and disease-free survival.

RESULTS

No patient in group 1 died from papillary thyroid carcinoma, compared with three patients in group 2 and six in group 3. There was a statistically significant difference in carcinoma-specific survival between groups 1 and 2 (P = 0.033). Two patients in group 1, six in group 2 and eight in group 3 developed recurrence. The difference in disease-free survival between groups 1 and 2 was significant (P = 0.025). One patient in group 1, three in group 2 and four in group 3 died from follicular thyroid carcinoma, but there were no significant differences in survival between the three groups.

CONCLUSION

Extension of the pT1 classification to cover all tumours up to 20 mm does not appear to be justified for papillary thyroid carcinoma.

PPARgamma staining as a surrogate for PAX8/PPARgamma fusion oncogene expression in follicular neoplasms: clinicopathological correlation and histopathological diagnostic value

The PAX8/PPARgamma (PPFP) fusion-oncogene is moderately specific for follicular thyroid carcinomas (FTC). It remains unknown whether this can be translated into improved diagnosis, classification, or outcome prediction. We studied a cohort of well-characterized follicular adenomas (FA), FTC, and Hurthle cell carcinomas (HCC) from patients with complete clinical follow-up, to determine whether PPARgamma immunohistochemistry (as a surrogate of PAX8/PPARgamma expression) helps to distinguish FA from FTC and to assess its diagnostic accuracy as an adjunct to frozen section. We also correlated PPARgamma staining with clinical outcomes to assess its role as a prognostic marker.PPARgamma staining was more common in FTC (31 of 54; 57%) than in HCC (one of 23; 4%) or FA (four of 31; 13%) (P < 0.000001). Adjunctive use of PPARgamma immunohistochemistry improved diagnostic sensitivity of intraoperative frozen section from 84% to 96% (P < 0.05) but reduced specificity from 100% to 90% (P < 0.05). PPARgamma staining was associated with favorable prognostic indicators (female gender, better tumor differentiation, and lesser risk of metastases).PPARgamma staining may be helpful in the differential diagnosis of FA, FTC, and HCC, particularly when diagnostic sensitivity of histomorphology is reduced (e.g. during intraoperative frozen section). PPARgamma staining also shows an association with favorable prognosis and may have a role in risk stratification.

Prognostic indicators in differentiated thyroid carcinoma

BACKGROUND

Thyroid cancer ranges from well-differentiated lesions with an excellent prognosis to anaplastic carcinoma, which is almost uniformly fatal. Thus, methods to assess the behavior of thyroid malignancies are necessary to arrive at appropriate treatment decisions.

METHODS

We discuss the factors that affect the prognosis of patients with well-differentiated thyroid malignancies, including papillary, follicular, Hürthle cell, and medullary thyroid carcinomas. We also review the presentation, therapy, and outcome of patients seen at our center over a span of 50 years. These data have identified those prognostic factors that are predictive of survival and recurrence in differentiated thyroid cancer.

RESULTS

Several classifications with different variables have been developed to define risk-group categories. Three widely used systems, in addition to the TNM staging system, include AGES, AMES, and MACIS.

CONCLUSIONS

A better understanding of independently important prognostic variables will result in improved patient care and treatment.

Treating the patient with differentiated thyroid cancer with thyroglobulin-positive iodine-131 diagnostic scan-negative metastases: including comments on the role of serum thyroglobulin monitoring in tumor surveillance

Differentiated thyroid cancer (DTC) patients, especially the 10% to 15% at high risk of cancer-related death, should have long-term monitoring for detection of recurrence or metastasis. Conventional radiologic and ultrasonographic imaging is useful for localization of recurrent or persistent disease. For patients who have had ablation of residual thyroid tissue, measurement of serum thyroglobulin (Tg) levels and radioactive iodine (RAI) imaging provide highly sensitive tools for early detection. Serum Tg is reliable only in the absence of Tg autoantibodies. Sensitivity increases with TSH stimulation, either by withdrawal of thyroxine (T4) therapy, or administration of recombinant TSH (rTSH). In some patients, serum Tg levels are positive but the RAI whole body scan (WBS) is negative. In these patients, either the recurrent tumor is too small and below the sensitivity of the diagnostic scan, or there is a dissociation between Tg synthesis and the iodine-trapping mechanism. Recent literature suggests that empiric high-dose RAI therapy of Tg-positive diagnostic scan-negative patients may result in a high rate of visualization of uptake in posttherapy scans (PTS). Evidence for subsequent improvement of parameters of disease activity has also been presented. Almost all such reported cases had micrometastases that were not visualized by conventional imaging. In our experience, aggressive macrometastases with negative diagnostic WBS do not show significant uptake after therapeutic doses of RAI. The small size of micrometastases in the first group of patients and a possible defect of the iodine-trapping mechanism in the second group may explain this apparent discrepancy. Based on presently available information, a generalized recommendation for RAI therapy of Tg-positive, diagnostic scan-negative patients should await further studies. Meanwhile, in some high-risk patients, in the absence of alternative therapies, empiric RAI therapy is justified.