Microscopically positive surgical margins and local recurrence in thyroid cancer. A meta-analysis

This abstract was submitted for presentation at the 6th World Congress of the International Federation of Head and Neck Oncologic Societies IFHNOS, Buenos Aires, Argentina. 2018.
https://doi.org/10.1016/j.ejso.2019.02.007Get rights and content

Abstract

Background

Microscopically positive surgical margins are a prognostic factor of recurrence in advanced thyroid carcinoma. However, information on early and completely resected thyroid tumors is scarce. Some studies do not identify any association between positive margin and local recurrence. The objective of this study was to perform a meta-analysis to measure the association of microscopically positive surgical margins and local recurrence in patients who underwent total thyroidectomy.

Methods

Clinical trials assessing the association between microscopically positive surgical margin and local recurrence in patients with early-stage, well-differentiated thyroid carcinoma who underwent total thyroidectomy were evaluated. The outcome measured was local recurrence in the thyroid bed. A systematic review and meta-analysis was done using a random-effects model.

Results

Six studies with 7696 patients were identified. Methodological quality was good, and we did not identify statistical heterogeneity or publication bias. The risk difference for microscopically positive surgical margin and local recurrence was 0% (95% CI 0 to 1).

Conclusion

Meta-analysis did not find a statistically significant association between microscopically positive surgical margin and local recurrence in this population. A finding of microscopically positive surgical margin in the absence of other adverse factors is not an indication for adjuvant treatment.

Introduction

A positive surgical margin (PSM) is the most relevant predictor of local recurrence in malignant tumors [[1], [2], [3]]. Achieving clear margins at resection can decrease the rate of recurrence. However, the effect of margin status on prognosis varies with both histology and organ. Thyroid cancer is the most common endocrine tumor, and several specialties, including surgery, nuclear medicine, endocrinology, radiotherapy, medical oncology and histopathology, participate in its multidisciplinary management and indication of adjuvant treatment [4,5].

The most important risk factors for local recurrence in thyroid cancer are gross extrathyroidal extension (ETE), evidence of residual gross disease at completion of surgery and a histologically confirmed positive margin on pathology. However, there are differences between macroscopic and microscopic margins, and the importance of microscopically positive surgical margin (MPSM) has not been comprehensively evaluated in well-differentiated thyroid carcinoma (WDTC). As there are various clinical presentations and biological behaviors of thyroid malignancies, the finding of a MPSM may not have the same impact in all cases. Most intrathyroid tumors remain stable for years [6], while others invade adjacent structures early [7]. Finally, the differentiation of the prognostic value of MPSM from that of extrathyroidal extension (ETE) or lymphovascular invasion (LVI) is important in the decision-making process and in the selection of adjuvant treatments.

The objective of the present study was to determine the association between MPSM and local recurrence in patients with early-stage WDTC who underwent total thyroidectomy, using a systematic review method.

Section snippets

Materials and methods

This review was registered at the International prospective register of systematic reviews (PROSPERO) with the number CRD42018085377. The review followed the recommendations of the MOOSE guidelines [8]. Clinical trials that evaluated the presence or absence of MPSM in surgical specimens of total thyroidectomy for early WDTC were evaluated. No limitations on the number of patients, source, language of the article or follow-up time were considered. The studies included adult patients with a

Results

In total, 108 references were reviewed, and only seven studies were identified by the primary search (Fig. 1) [[11], [12], [13], [14], [15], [16], [17]]. Later, a study by Tsang et al. [17] was excluded due to inclusion of various histological types and extension of treatments. Inclusion criteria were similar for all studies: patients with WDTC or PTC, with the primary tumor limited to the thyroid gland and who underwent total thyroidectomy with/without central/lateral neck dissection. Only one

Discussion

A positive margin is an important prognostic factor for local recurrence in locally advanced thyroid cancers [18]. Studies from reference centers have shown an obvious increase in recurrence rates and a decrease in overall survival if the definitive margins are reported as positive [19]. Examples of this effect are evident in cases of shaving tumors off the trachea or esophagus [20]. Kim et al. [21] reported that in a series of advanced thyroid tumors, a microscopic positive margin increased

Conflict of interest

Authors don't have conflict of interest.

Funding

No external funding to this study.

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