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EDITORIAL |
From the Division of Endocrine and Oncologic Surgery, Johns Hopkins Hospital, Baltimore, Maryland.
Correspondence: Address correspondence to: Robert Udelsman, MD, FACS, Johns Hopkins Hospital, Blalock 688, 600 N. Wolfe Street, Baltimore, MD 21287; Fax: 410-614-2913; E-mail: rudelsma{at}jhmi.edu
In the current issue of Annals of Surgical Oncology, Brooks and colleagues at Memorial Sloan-Kettering Cancer Center review their experience with 564 patients who underwent thyroidectomy between January 1996 and June 1999.1 In reviewing the data, it is important to acknowledge that their population is reflective of a large tertiary cancer center where more than 50% of their patients proved to have malignant thyroid disease. The authors evaluated the impact of fine-needle aspiration (FNA) and intraoperative frozen section on the management of patients with dominant thyroid nodules. Several important points merit additional emphasis.
Thyroid nodules are common, occurring in approximately 15% of the female population in the United States. A major role of FNA, not addressed in the Brooks et al. article, is that it helps select patients who are appropriate candidates for surgery.2 Because the entry criteria for the current study were patients who underwent thyroidectomy, there is little doubt that a large population of patients was not included because they had a benign FNA and were never referred for surgery. A major attribute of a benign FNA is that it reassures both the patient and the clinician that careful observation may be appropriate and a large number of thyroidectomies are thereby obviated. Therefore, the importance of FNA in the evaluation of thyroid nodules should not be minimized.
Does a "benign" FNA guarantee that a nodule is surely benign? No. How often is an FNA a false-negative finding? The authors clarify this issue by presenting data both in terms of patients who had clinically significant thyroid cancer as well as for those noted to have incidental thyroid cancer (defined both as tumors < 10 mm and < 5 mm, respectively) noted on permanent histology. In this series, the false-negative rate for clinically significant (assuming a 10 mm cutoff) thyroid cancer was 4%. The authors thereby confirm that "a negative FNA should not be used as reassurance if other clinical factors are suggestive of malignancy."
Does a "malignant" FNA guarantee cancer? No. In this series, the false-positive rate was 4.6% when microcarcinomas were considered benign (10 mm size cutoff). This relatively high rate is of some concern because the authors appropriately excluded FNA specimens that were considered unsatisfactory. The most common reason for an unsatisfactory FNA is an inadequate sample; a problem that can be overcome, in most cases, by on-site cytologic review. Clinicians caring for thyroid patients must also remember that thyroid cytology is an art that is dependent upon the adequacy of the specimen, its preparation, and the experience of the examiner.
What about frozen sections? The authors review the literature in a broad context. What is clear is that all thyroid nodules are not created equally. If a high quality FNA is unequivocally diagnostic for papillary or medullary carcinoma of the thyroid, then the diagnostic accuracy of FNA should approach 100%.2 In this setting, intraoperative frozen section is not helpful because it is unlikely to alter operative management. If the FNA demonstrates findings suspicious for, but not diagnostic of, papillary cancer of the thyroid, frozen section may be helpful.3 In this setting, addition of touch preparations of the specimen obtained in the frozen section suite may demonstrate the subtle cytologic findings diagnostic of the follicular variant of papillary carcinoma of the thyroid. If the FNA demonstrates a follicular or Hürthle cell neoplasm, it is highly unlikely that intraoperative frozen section will be informative with the exception of those cases where there are gross findings of malignancy.4,5 Under these conditions, a directed frozen section of an area of capsular penetration is likely to yield the diagnosis of cancer intraoperatively.
The authors aptly emphasize that "intraoperative examination of the thyroid gland and surrounding soft tissue adds more information for operative planning." What is also clear is that indications for a bilateral resection (total or near-total thyroidectomy) are often determined by (1) a known history of childhood exposure to low-dose external beam radiotherapy, (2) bilateral nodular thyroid disease, (3) an unequivocally positive FNA, especially when one plans postoperative 131I therapy, (4) or gross operative findings suggestive of malignancy which can be verified on a directed frozen section. However, as the authors note, "routine frozen section added little to management" and in their hands altered patient management in only 5% of cases.
The bottom line is—experience counts. Prudent evaluation of thyroid nodules including FNAs obtained and reviewed by experienced individuals combined with mature clinical judgement will reassure most patients that they are unlikely to harbor a malignant neoplasm and can be followed nonoperatively. Patients who demonstrate interval growth of a cytlogically "benign" nodule, patients who have indications for resection regardless of the FNA findings, as well as those with adequate FNAs diagnostic or suggestive of malignancy should be referred to an experienced thyroid surgeon. The surgeon must employ meticulous operative technique and examine not only the thyroid, but also the surrounding structures to determine the appropriate extent of resection. Judicious use of intraoperative frozen section can be helpful in select cases.
Received for publication December 1, 2000. Accepted for publication December 4, 2000.
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