Microscopically positive surgical margins and local recurrence in thyroid cancer. A meta-analysis
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.
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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.
References (27)
- et al.
A meta-analysis of margin size and local recurrence in oral squamous cell carcinoma
Oral Oncol
(2015) - et al.
The influence of the radicality of resection and dose of postoperative radiation therapy on local control and survival in carcinomas of the upper aerodigestive tract
Int J Radiat Oncol Biol Phys
(2000) - et al.
Advanced thyroid carcinoma: an experience of 385 cases
Eur J Surg Oncol
(2006) - et al.
Impact of extent of resection for thyroid cancer invading the aerodigestive tract on surgical morbidity, local recurrence, and cancer-specific survival
Surgery
(2010) - et al.
Operative management of locally advanced, differentiated thyroid cancer
Surgery
(2016) - et al.
Prognostic importance of "clear versus revised margins" in oral and pharyngeal cancer
Head Neck
(2010) - et al.
Practice patterns in the management of patients with differentiated thyroid cancer in ontario Canada 2000-2008
J Otolaryngol Head Neck Surg
(2014) - et al.
Variation in the management of thyroid cancer
J Clin Endocrinol Metab
(2013) - et al.
An observational trial for papillary thyroid microcarcinoma in Japanese patients
World J Surg
(2010) - et al.
Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis of observational studies in epidemiology (moose) group
J Am Med Assoc
(2000)