Definition of “Close Margin” in Oral Cancer Surgery and Association of Margin Distance With Local Recurrence Rate

Abstract

IMPORTANCE There is a lack of consistency in the literature regarding the definition of "close" resection margins in the surgical treatment of oral cavity squamous cell carcinoma (OCSCC), and the relationship between local recurrence (LR) rates and different distances of invasive tumor from surgical margin is not well characterized.OBJECTIVE To analyze the association between specific distances from invasive tumor to surgical margin and LR in patients with OCSCC. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study of 432 patients treated via en bloc resection for OCSCC between 2005 and 2014 at the University of Iowa Hospitals and Clinics. In all cases, permanent margin evaluation was performed on the main tumor specimen and with intraoperative frozen section margin assessment from the tumor bed. MAIN OUTCOMES AND MEASURESThe LR rate based on minimum millimeter distance between invasive tumor and inked main specimen margin. RESULTSOf the 432 participants, 252 (58%) were men and 180 (42%) were women (mean age, 62.14 years; range, 19-99 years). In each case, the LR rate was analyzed in relation to each millimeter distance of invasive cancer from the inked main specimen margin, with results showing an exponential inverse relationship. The LR rate for microscopic positive margins was 44% (95% CI, 34%-55%); for margins less than 1 mm, 28% (95% CI, 18%-41%); for 1 mm, 17% (95% CI, 8%-31%); for 2 mm, 13% (95% CI, 6%-27%); for 3 mm, 13% (95% CI, 5%-32%); for 4 mm, 14% (95% CI, 5%-35%); and for 5 mm or greater, 11% (95% CI, 6%-18%). Analysis of the receiver operating characteristic curve identified a cutoff of less than 1 mm as appropriate for classifying higher risk of local recurrence. Regardless of margin distance, resection of additional tissue beyond 1 mm based on intraoperative frozen section was not associated with improved local control. CONCLUSIONS AND RELEVANCEThe commonly used cutoff of 5 mm for a close margin lacks an evidential basis in predicting local recurrence. Invasive tumor within 1 mm of the permanent specimen margin is associated with a significantly higher local recurrence rate, though there is no significant difference for greater distances. This study suggests that a cutoff of less than 1 mm identifies patients at increased local recurrence risk who may benefit from additional treatment. Analysis of the tumor specimen rather than the tumor bed is necessary for this determination.

Narrow Band Imaging‐guided resection of oral cavity cancer decreases local recurrence and increases survival

“…Rather, the main specimen margin is most strongly predictive of this, regardless of whether the margin was ultimately cleared with additional resection. This argues against the practice of routine intra‐operative sampling of the tumour bed for margin assessment (Tasche et al., ) and supports our approach of appropriate assessment of the main specimen margin using an optical imaging technique such as NBI.…”

“…Random algorithms such as 5–10 mm clearance around the tumour are unacceptable, as they do not allow personalisation of the resection and do not resolve the issue of local recurrence given that up to 20% of cases fail due to local recurrence, necessitating salvage surgery and/or chemoradiotherapy (Anderson et al., ). Practices involving wider resection margins greater than 1 cm around the tumour are not appropriate given that most tumours are not symmetrical, and therefore, resecting tissue 1–2 cm from the visible tumour extent may not necessarily remove all abnormal tissue at all mucosal margins (Tasche, Buchakjian, Pagedar, & Sperry, ). The injudicious removal of additional tissue may also compromise wound closure and lengthen wound healing increasing morbidity.…”

“…This is also extremely supportive and re‐assuring of the power of NBI‐guided surgical margin delineation over WL in improving outcomes for late stage advanced cases (Stages III/IV), which have dismal survival rates (35.9%) (Lopez‐Cedrun & Andres de Llano, ) and a higher than usual recurrence rate (39%) (Noble et al., ). Furthermore, although some past studies have shown benefit of frozen section assessment intra‐operatively, the latest evidence demonstrates that achieving a negative margin from additional tissue resection is not associated with improved local recurrence rate (LRR) or overall prognosis (Tasche et al., ). Rather, the main specimen margin is most strongly predictive of this, regardless of whether the margin was ultimately cleared with additional resection.…”

The role of adjuvant treatment in early‐stage oral cavity squamous cell carcinoma: An international collaborative study

“…Although patients with T1‐2N0M0 OCSCC can be treated with surgery alone, those with positive and close margins may benefit from adjunctive treatment . It has been suggested that adequate resection of OCSCC requires at least 5‐mm margins, although smaller margins have also been suggested . Because of the complexity of these tumors, clear margins are achieved in only 50% to 80% of patients treated at cancer centers .…”

Tumor margin classification of head and neck cancer using hyperspectral imaging and convolutional neural networks

“…3 Another study found cuts within 1 mm of oral cavity SCCa tumor margins are associated with significantly increased recurrence rates. 4 Additionally, the incidence rate for differentiated thyroid carcinomas in the United States is approximately 20 per 100,000 females and 6 per 100,000 males, predominantly papillary and follicular carcinoma. 5 Similarly, negative resection margins are the primary prevention of disease recurrence for thyroid cancer.…”