Margins of Resection in Head and Neck Squamous Cell Carcinoma

Surgical margin status:
- Remains one of the most powerful and actionable prognostic factors in oral tongue / oral cavity SCC
Classically, Scholl and colleagues:
- Reviewed 268 patients with squamous carcinoma of the oral tongue:
  - They found that 54 (20.1%) had microscopic “cut-through” at the intraoperative frozen section margin:
    - An initially positive margin
- Even when additional resection converted these to final negative margins:
  - Local control remained significantly worse:
    - Than in patients whose margins were clear on the first pass
- They also reported that margin involvement patterns differed by T stage:
  - T1 to T2 tumors:
    - More often had positive mucosal margins
  - T3 to T4 tumors:
    - Commonly failed at the deep / soft-tissue margins
Similar observations were made in classic series evaluating “positive” epidermoid carcinoma margins in the head and neck:
- Looser, Shah, and Strong:
  - Demonstrated that patients with involved margins:
    - Had substantially higher local recurrence than those with negative margins:
      - With early reports quoting local recurrence in roughly two-thirds to three-quarters of patients with positive margins versus about one-third with negative margins
- Loree and Strong:
  - Subsequently examined 398 oral cavity SCCs:
    - Showing that positive or “close” margins (tumor at or within 0.5 mm of the inked edge, or significant premalignant change / in situ carcinoma at the margin):
      - Were associated with a doubling of local recurrence (36% vs 18%) and inferior 5-year survival compared with negative margins (52% vs 60%)
The reliability and utility of intraoperative frozen section (FS) margin assessment have also been extensively studied:
- Spiro et al:
  - Reported an overall intraoperative FS diagnostic accuracy of approximately 89% for oral tongue cancer:
    - Importantly found that accuracy was similar whether sections were taken directly from the patient’s tumor bed or from the oriented surgical specimen
  - Positive or “close” margins:
    - Defined in their series as tumor present at the ink or within roughly one high-power field of the resection edge:
      - Were associated with a significantly increased risk of local recurrence (p < 0.003)
- Subsequent work by Byers and others:
  - Confirmed the prognostic and therapeutic value of frozen section (FS):
    - Guided re-resection in HNSCC:
      - But also highlighted that FS cannot fully compensate for suboptimal initial resection planes
Definitions of margin status and distance:
- There is now better consensus on margin nomenclature
- Most contemporary series and guidelines define:
  - Positive margin:
    - Invasive carcinoma or severe / high-grade dysplasia:
      - At the inked edge, or < 1 mm from the inked edge
  - Close margin:
    - Invasive carcinoma typically 1 to 4 or 1 to 5 mm from the inked edge:
      - Cut-off values vary:
      - But a 5 mm microscopic threshold is most commonly used in oral cavity SCC
  - Clear margin:
    - ≥ 5 mm from invasive tumor to the inked edge after formalin fixation
Tasche et al., in a large JAMA Otolaryngology analysis:
- Proposed that a distance < 1 mm behaves biologically like an involved margin:
  - With similarly high local recurrence risk
- Whereas 1 to 5 mm margins had intermediate risk and ≥ 5 mm margins were associated with the lowest recurrence
More recent multicenter work emphasizes the importance of deep margin distance in particular:
- With data suggesting that deep margins ≤ 3 mm carry a significantly higher risk of local failure compared with > 3 mm:
  - Even when the mucosal margin is wide
Impact of positive and close margins on outcomes:
- Multiple retrospective series and meta-analyses now support and refine the early observations of Scholl, Looser, Loree, and Strong:
  - Positive final margins are consistently associated with:
    - ~ 2-fold higher risk of local recurrence,
      increased regional / distant failure in some series, and significantly worse disease-specific and overall survival
- Binahmed et al. and McMahon et al:
  - Both showed that patients with involved margins:
    - Had roughly double the local recurrence and significantly poorer survival compared with those with clear margins, and that close margins behaved intermediately between clearly negative and frankly positive margins
- Liao et al:
  - Identified margin status, together with T stage, DOI, and perineural invasion:
    - As major predictors of local tumor control in oral cavity SCC
- A 2019 systematic review and meta-analysis by Gorphe:
  - Concluded that positive margins carry an approximately two-fold increased risk of death and local failure across head and neck sites, independent of other factors
- More granular contemporary analyses, including Buchakjian et al. and Szewczyk et al., have shown that:
  - Positive margins (< 1 mm) remain the strongest margin-related predictor of:
    - Local, regional, and distant recurrence
  - Close margins (1 to 4.9 mm) often do not independently worsen outcomes if other adverse factors (lymphovascular invasion, perineural invasion, ENE, nodal disease, advanced T stage):
    - Are absent and if appropriate adjuvant therapy is given when indicated
- The prognostic effect of close margins is modulated by:
  - Depth of invasion, pattern of invasion, and composite histologic risk models (e.g., Brandwein-Gensler)
- Subsite-specific studies have further refined this:
  - Tongue and floor-of-mouth tumors are particularly prone to failure at the deep margin:
    - In several series, deep margin positivity or ≤ 2 to 3 mm clearance:
      - Has been more predictive of local recurrence than mucosal margin distance
Microscopic cut-through and “revised” margins:
- Building on Scholl’s original work, the concept of microscopic tumor cut-through (MTCT):
  - A positive FS margin that is revised to negative on final pathology, has been extensively studied
  - Patel et al. (Head & Neck 2010) showed that MTCT:
    - Was associated with significantly worse local control and disease-specific survival compared with margins that were negative from the outset:
      - Particularly in patients with nodal disease
  - Guillemaud et al. similarly reported that intraoperative cut-through, even if revised to R0:
    - Predicted higher local recurrence and worse outcomes in oral cavity SCC
  - A meta-analysis by Bulbul et al. concluded that clearance of a positive margin improves outcomes relative to leaving it unrevised:
    - But patients with MTCT still fare worse than those whose margins were always negative:
      - Suggesting MTCT is a marker of more aggressive biology and / or challenging local anatomy
  - More recently, Agne et al. evaluated T3 to T4 OCSCC and confirmed that MTCT:
  - remained an independent predictor of local recurrence on multivariable analysis (HR ~1.8–2.2 for local failure):
    - Although its effect on disease-specific survival attenuated when controlling for nodal stage and other high-risk features
These data support considering MTCT as a high-risk feature warranting discussion of treatment intensification:
- For example (e.g., adjuvant chemoradiotherapy) in a multidisciplinary tumor board, even when final margins are technically negative
Kwok et al. addressed the related question of “clear versus revised margins” in 417 patients with oral and pharyngeal carcinoma:
- Patients who required immediate re-resection for a positive FS margin but ended with R0 status:
  - Had survival similar to those with primary R0 resection, and both groups did substantially better than patients left with residual microscopic or macroscopic disease
- This suggests that while MTCT carries biologic risk:
  - An aggressive intraoperative strategy to convert to R0 is still beneficial and should remain standard practice
Intraoperative margin assessment:
- Specimen vs tumor bed:
  - There is growing recognition that how margins are sampled:
    - Is almost as important as the final measurement
  - Meier et al.’s AHNS survey and several subsequent series have documented wide variation in intraoperative margin practices (tumor bed vs specimen mapping, number of samples, definition of “adequate” clearance), and a substantial rate of FS–permanent section discrepancy
- Key contemporary points include:
  - Specimen-based mapping (oriented and inked, with communication between surgeon and pathologist):
    - Tends to provide more reliable correlation between FS and final margins than random tumor-bed biopsies
  - FS accuracy remains high (often ~ 85% to 95%):
    - But false-negatives and false-positives still occur:
      - Particularly at the deep margin, in previously irradiated fields, and in specimens with significant shrinkage
  - In some series, “complete FS margins” with a measurable 1 to 5 mm histologic buffer were associated with improved local control compared with conventional limited sampling
- Recent reviews and consensus statements (e.g., Kubik et al., Kain et al., Chen et al. 2024) now recommend:
  - A planned 1 to 1.5 cm gross resection margin in vivo for oral tongue SCC, anticipating ~30% to 50% shrinkage with formalin fixation and tissue relaxation
  - Routine use of oriented, inked specimens with targeted FS from high-risk areas (deep margin, close relationship to muscle bundles or neurovascular structures)
  - Consideration of advanced adjuncts—near-infrared fluorescence mapping, specimen 3D-mapping, and emerging augmented-reality registration—for difficult tongue and floor-of-mouth resections
Integration with histologic risk models:
- Finally, margin status must be interpreted in the context of overall histologic risk
- The Brandwein-Gensler model:
  - Worst pattern of invasion, perineural invasion, lymphocytic host response and later refinements:
    - Have shown that high-risk tumors have markedly increased recurrence and disease-specific mortality even when margins are clear
- Conversely, some low-risk early-stage tumors with close (but not involved) margins may do well without aggressive adjuvant therapy
- This supports a nuanced, risk-adapted approach in which:
  - Positive margins or MTCT → strong indication for adjuvant chemoradiotherapy in most patients
  - Close margins (1 to 4 mm) → individualized decision based on DOI, nodal status, PNI/LVI, pattern of invasion, and patient-specific factors
  - Clear margins (≥ 5 mm) → lowest risk group, managed according to other adverse features.
Reviewed:
- Scholl P, Byers RM, Batsakis JG, Wolf P, Santini H. Microscopic cut-through of cancer in the surgical treatment of squamous carcinoma of the tongue: prognostic and therapeutic implications. Am J Surg. 1986;152:354-360.
- Looser KG, Shah JP, Strong EW. The significance of “positive” margins in surgically resected epidermoid carcinomas. Head Neck Surg. 1978;1:107-111.
- Loree TR, Strong EW. Significance of positive margins in oral cavity squamous carcinoma. Am J Surg. 1990;160:410-414.
- Spiro RH, Guillamondegui O, Paulino AF, et al. Pattern of invasion and margin assessment in patients with oral tongue cancer. Head Neck. 1999;21:408-413.
- Chen TY, Emrich LJ, Driscoll DL. The clinical significance of pathological findings in surgically resected margins of the primary tumor in head and neck carcinoma. Int J Radiat Oncol Biol Phys. 1987;13:833-837.
- McMahon J, O’Brien CJ, Pathak I, et al. Influence of condition of surgical margins on local recurrence and disease-specific survival in oral and oropharyngeal cancer. Br J Oral Maxillofac Surg. 2003;41:224-231.
- Binahmed A, Nason RW, Abdoh AA. The clinical significance of the positive surgical margin in oral cancer. Oral Oncol. 2007;43:780-784.
- Liao CT, Chang JTC, Wang HM, et al. Analysis of risk factors of predictive local tumor control in oral cavity cancer. Ann Surg Oncol. 2008;15:915-922.
- Patel RS, Goldstein DP, Guillemaud J, et al. Impact of positive frozen section microscopic tumor cut-through revised to negative on oral carcinoma control and survival rates. Head Neck. 2010;32:1444-1451.
- Guillemaud J, Patel RS, Goldstein DP, et al. Prognostic impact of intraoperative microscopic cut-through on frozen section in oral cavity squamous cell carcinoma. J Otolaryngol Head Neck Surg. 2010;39:370-377.
- Kwok P, Gleich O, Hübner G, Strutz J. Prognostic importance of “clear versus revised margins” in oral and pharyngeal cancer. Head Neck. 2010;32:1479-1484.
- Gorphe P. A systematic review and meta-analysis of margins in head and neck cancer. Oral Oncol. 2019;95:93-101.
- Tasche KK, Buchakjian MR, Pagedar NA, Sperry SM. Definition of “close margin” in oral cancer surgery and association of margin distance with local recurrence rate. JAMA Otolaryngol Head Neck Surg. 2017;143:1166-1172.
- Buchakjian MR, Tasche KK, Robinson RA, et al. Association of main specimen and tumor bed margin status with local recurrence and survival in oral cancer surgery. JAMA Otolaryngol Head Neck Surg. 2016;142:1191-1198.
- Kain JJ, Birkeland AC, Udayakumar N, et al. Surgical margins in oral cavity squamous cell carcinoma: current practices and future directions. Laryngoscope. 2020;130:128-138.
  Szewczyk M, et al. A matter of margins in oral cancer—how close is enough? Cancers (Basel). 2024;16(8):1488.
- Agne GR, et al. Oncologic outcomes of microscopic tumor cut-through in locally advanced oral squamous cell carcinoma. Arch Head Neck Surg. 2022;51:e20220013.
  Chen Y, et al. Surgical margins in head and neck squamous cell carcinoma. Int J Surg. 2024;109:54-66.
- Brandwein-Gensler M, et al. Oral squamous cell carcinoma: histologic risk assessment, but not margin status, is strongly predictive of local disease-free and overall survival. Am J Surg Pathol. 2005;29:167-178.