Elective Neck Dissection, but Not Adjuvant Radiation Therapy, Improves Survival in Stage I and II Oral Tongue Cancer with Depth of Invasion >4 mm

Abstract

In early-stage, node negative oral tongue cancer, there is limited data supporting tumor depth of invasion (DOI) as an indication for post-operative radiotherapy (PORT) to the primary site. The primary aim of this study is to examine the effect of tumor DOI and PORT on overall survival (OS). Materials and methods The National Cancer Database (NCDB) was used to query patients with AJCC stage I and II oral tongue cancer (2006-2013). Patients were stratified by receipt of PORT, elective neck dissection (ND), and DOI (≤4 mm or >4 mm). Kaplan-Meier analysis was performed to compare OS (using the log-rank test) between PORT versus no-PORT. Multivariable Cox proportional hazards regression model performed to evaluate the independent effect of PORT and neck dissection on OS. Results Among 939 patients, 69.3% were clinical stage I, 67.4% received ND, 23.4% had DOI >4 mm, and 10.4% received PORT. The addition of PORT did not improve OS with tumor DOI ≤4 mm (p = 0.634) or >4 mm (p = 0.816). The addition of elective neck dissection improved OS for DOI >4 mm (p = 0.010), but not for ≤4 mm (p = 0.128). On multivariable analysis, ND improved OS if DOI >4 mm (HR, 0.37; 95% CI, 0.17-0.81 [p = .012]), when also controlling for age, sex, PORT status, clinical stage, and pathological stage. Conclusion Tumor DOI should not be used as a sole indication for PORT in early stage oral tongue cancers. Elective neck dissection at the time of excision of the primary tumor results in higher OS for tumors with DOI >4 mm.

Depth of invasion versus tumour thickness in early oral tongue squamous cell carcinoma: which measurement is the most practical and predictive of outcome?

“…After DOI was included in the AJCC pT staging, most recent studies for OSCC and OTSCC have incorporated clear definitions of DOI and TT using the criteria proposed by the AJCC 12,13,15,20–22,27,28 . However, studies which have confused these two measurements 11 or did not provide a definition 14,27,29–31 continued to be reported in the literature. Additionally, a recent survey of 159 surgeons has shown that 18% of survey participants confused the definition of DOI with TT 10 …”

“…A recent survey of 159 surgeons has shown that 18% of the survey participants define DOI as the distance from the mucosal surface of the tumour to the deepest point of invasion, which is the exact definition of TT 10 . Additionally, a large retrospective study published in 2019 has defined DOI using the criterion of TT as length measured from the tumour surface to the deepest point of invasion 11 …”

Staging more important than grading? Evaluation of malignancy grading, depth of invasion, and resection margins in oral squamous cell carcinoma

“…Because of its relevance regarding outcome and the presence of LM, preoperative and adjuvant choice of therapeutic options, especially elective neck dissection, should take DOI into consideration. Though, due to contradicting reports [56,57], it remains unclear, how to identify patients, especially with early-stage cancer, that would benefit from elective neck dissection. Several methods of evaluating DOI during the pretherapeutic staging process have been evaluated.…”

Compartmental tongue surgery for intermediate‐advanced squamous cell carcinoma: A multicentric study

“…The gold standard for stages I‐II OTSCC is transoral surgical excision with elective neck dissection if the pathological depth of invasion (DOI) is more than 4 and up to 9 mm 9,10 . Stages III‐IV OTSCC, with a DOI ≥10 mm, should be managed by “en‐bloc” tumor removal and concomitant neck dissection carrying out a so called standard wide margins surgery (SWMS) or, alternatively, a compartmental surgery (CTS) approach 11 .…”