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Updates on Management of Papillary Thyroid Carcinoma
From: ENT Today, July 2007
by Jennifer Decker Arevalo, MA
SAN DIEGO-Several scientific sessions at the 2007 Combined Otolaryngology Spring Meeting focused on the topic of papillary thyroid cancer (PTC), which accounts for about 75% of thyroid cancers in the United States.1 As members of the American Head and Neck Society (AHNS), Tarik Y. Farrag, MD, and Mark G. Shrime, MD, presented the results of their studies, Identifying Patients Undergoing Thyroidectomy for Papillary Thyroid Cancer at Risk for Harboring Multiple Central Neck Lymph Node Metastases and Cost-Effective Management of Low-Risk Papillary Thyroid Carcinoma, respectively.
Timing of Central Neck Dissection
Dr. Farrag, a postdoctoral fellow in the Department of Otolaryngology-Head & Neck Surgery at Johns Hopkins School of Medicine, performed a retrospective chart review of 51 consecutive patients with PTC who underwent primary thyroidectomy and concurrent removal of central neck lymph nodes (LN) between March 2000 and November 2006 at Johns Hopkins to identify the patient population with PTC undergoing primary thyroidectomy at risk for harboring multiple central neck LN metastases.
This is the first time the concept has been addressed by this approach, said Dr. Farrag. Due to the potential complications associated with central LN dissection, there is controversy in the current literature on when to do it, and what the factors are that could reliably predict a positive disease in this compartment in this subset of patients, which then could justify an extensive central compartment dissection at the time of primary thyroidectomy.
Study participants were divided into two categories: (1) 15 patients whose operative notes indicated direct removal of suspicious LN(s) only (1-6 LNs removed; median = 2), and (2) 36 patients whose operative notes showed that an attempt was made to clear more than just suspicious LNs (4-27 LNs; median = 13). The second category was further divided into two groups based on whether the patient was (A) negative or (B) had positive multiple LNs on final pathology.
Comparisons between A and B were performed utilizing four factors, which had the following results:
- Primary tumor size ≥ 3cm: positive predictive value (PPV) = 82%; sensitivity (S) = 45%.
- Lateral neck LN metastasis detected by preoperative imaging (ultrasound and/or CT) and confirmed by fine needle aspiration and/or intraoperative frozen section: PPV = 89%; S = 63%.
- Preoperative suspicion of central LN metastasis based on physical exam and imaging: PPV = 100%; S = 26%.
- Intraoperative suspicion or histopathologic confirmation of central neck LN metastasis: PPV = 93%; S = 91%; p = 0.008.
Our study demonstrated that intraoperative central LN evaluation is an important step during thyroidectomy for PTC to predict those who are likely to harbor multiple LN metastases, said Dr. Farrag. The other three factors were found to be highly predictive for patients harboring multiple central nodal metastases; however, they had variable sensitivity.
The authors recommend that a central neck dissection maximizing the number of LNs removed should be performed when factor 4 (see list above) is present and should be considered when the other factors are present as well, to reduce the chance of central compartment recurrence, and therefore, reoperation.
Unlike other lymph node dissections, the central nodal dissection has not been fully standardized in the current literature, as to the extent of resection, the expected nodal yield, and the factors that could predict positive disease in this compartment, said Dr. Farrag. Therefore, in our study, we have evaluated some of these factors to highlight their importance in the evaluation of patients with PTC undergoing primary thyroidectomy, to help in the decision-making process of their surgical treatment.
Cost-Effective Management of PTC
Dr. Shrime, a fellow in Head and Neck Oncologic and Reconstructive Surgery at the University of Toronto Health Network and Mount Sinai Hospital in Canada, spoke on the cost-effectiveness of total thyroidectomy versus hemithyroidectomy in the management of small PTCs in low-risk patients, based on published recommendations of the American Thyroid Association.
Since there appears to be no significant difference in quality of life or mortality between the two procedures, then that leaves the door open for a cost-effectiveness study to be performed, said Dr. Shrime.
For his study, Dr. Shrime conducted a systematic literature review of 1605 abstracts to pinpoint key statistics for decision analysis, including rates of: (1) recurrence, (2) complications for all interventions undertaken, and (3) death.
Within the decision tree model, each of these possible strategies leads to another branch being added to the tree and there is a cost and probability associated with each branch, said Dr. Shrime. For example, the vast majority of patients will have uncomplicated surgeries, but a smaller number will follow one of the many 'complications' branches.
Once the tree is drawn, we then fill in all of the costs and probabilities associated with each branch and calculate which particular branch is most cost-effective, as well as provides the best overall survival and/or recurrence-free survival.
After identifying initial results, Dr. Shrime and his colleagues also performed sensitivity and threshold analysis to assess the strength of their recommendations.
Based on their calculations, total thyroidectomy and its follow-up cost $13,910, whereas hemithyroidectomy and its follow-up cost $15,064. Cause-specific mortality was similar for both treatment strategies, whereas recurrence-free survival and recurrence/complication-free survival were both improved by total thyroidectomy. Sensitivity and threshold analyses demonstrated these results to be very robust. Initial hemithyroidectomy presents a more costly overall treatment protocol in patients with low-risk PTC.
Having achieved these results, it is important to point out that cost-effectiveness studies, like any study have inherent problems with them, said Dr. Shrime. Assumptions, even if they are lessened somewhat by sensitivity analyses, are made and may still bias results in one way or another.
I think cost-effectiveness studies are only an indication of possibly what should be done, added Dr. Shrime. I don't think they are the ultimate arbiter of the way medicine should be practiced, nor do they necessarily reflect the actual practice patterns in place.
I do think it's a significant finding that total thyroidectomy dominates these calculations and I think it should give people pause, even if it ends up being that hemithyroidectomy, given the way physicians actually practice, rather than the idealized consensus recommendations, becomes more cost-effective. But I don't think physicians should end up basing all their decisions on costs. What they should do, instead, is prod the community to undertake the stronger, but harder to do, randomized controlled trials.
- Jemal A, Murray T, et al. Cancer statistics, 2005. CA Cancer J Clin 2005 Jan-Feb;55(1):10-30. Erratum in: CA Cancer J Clin 2005 Jul-Aug;55(4):259.
©2007 The Triological Society