Sentinel node biopsy in early oral squamous cell carcinomas: Long-term follow-up and nodal failure analysis
Introduction
The management of T1/T2 cN0 oral squamous cell carcinoma (OSCC) remains controversial, with the two historical attitudes of watchful waiting and neck dissection (ND). The presence of lymph node metastases in the neck represents one of the most important adverse prognostic factors for patients with OSCC [1]. However, current imaging techniques are not considered to be sufficiently sensitive to detect occult lymphatic disease in cN0 neck [2]. With ND, it is expected that approximately 20% of cN0 patients will be harboring lymphatic metastases [3], [4], and therefore benefit from this procedure. Conversely, the remaining patients, up to 80%, would have no evidence of metastases and could have been spared the unnecessary surgery. The risk for these patients is substantial, considering that even with the more preserving selective ND, significant postoperative morbidity may occur, such as spinal accessory nerve damage and shoulder dysfunction [5]. With greater importance placed in the patient's quality of life, the current approach in oncology is to reduce overtreatment, de-escalate, and use minimally invasive techniques whenever possible. The use of sentinel node biopsy (SNB) has therefore been gaining considerable interest as an alternative to ND [6], [7].
While SNB is now well-established in the management of melanoma and breast cancer, it is not yet standard of care in head and neck cancer [7]. Evidence supporting the use of SNB as a staging tool has been growing in the last several years, especially with recent reports of large prospective multicenter studies [8], [9], [10], [11]. In two multicenter trials that were carried out successively in the US to evaluate the accuracy of SNB, 140 and 101 T1/T2 cN0 OSCC patients underwent SNB followed by completion selective ND, yielding an NPV of 96% and 98%, respectively [8], [9]. In the first European multicenter trial that evaluated SNB accuracy as well as outcome, 125 T1/T2 cN0 oral/oropharyngeal SCC patients underwent either SNB alone or SNB-assisted elective ND; the overall sensitivity of SNB was 91%, NPV was 95%, and there was no statistically different survival difference between the two groups at 5-year follow-up [10]. In the Sentinel European Node Trial (SENT), 415 T1/T2 cN0 OSCC patients underwent SNB, followed by ND in case of positive SNs [11]. At 3-year follow-up, the NPV of SNB was 95% and disease-specific survival was 94%. Furthermore, a meta-analysis of 21 studies (847 patients) published between 2001 and 2012 on the accuracy of SNB in oral and oropharyngeal SCC showed an overall sensitivity of 93% [95% CI 90–95%] [12]. However, data on long-term follow-up is scarce, as well as data on regional failure and late nodal recurrence, leaving uncertainties as to the long-term outcomes of patients undergoing SNB compared to ND. In addition, low sensitivity and high false-negative rate have been observed with SNB in floor-of-mouth (FOM) tumors compared to other subsites [8], [10], hence limiting its applicability.
In order for SNB to be a true alternative to ND, there is a need to prospectively evaluate the long-term patient outcomes following SNB compared to ND and analyze the predictive factors of isolated nodal recurrence, considered as SNB failure. We previously reported our ten-year experience of the prospective cohort study on 166 patients with OSCC undergoing systematic or elective ND following SNB [13]. We report here the long-term follow-up results of a total of 249 patients and nodal failure analysis.
Section snippets
Study design and outcomes
This was a single-center, prospective cohort study, consisting of a primary study and a validation study. The primary study was conducted in order to evaluate the concordance between SNB and systematic ND findings in early OSCC. The primary objectives of the validation study were to evaluate the reliability of the SNB in a cohort with long-term follow-up in terms of recurrence rate, and to compare morbidity, overall survival (OS) and recurrence-free time (RFT) between patients having undergone
Patient and tumor characteristics
A total of 234 patients were included in the study. The first 53 consecutive patients underwent SNB and systematic ND (“systematic ND group”). The following 181 consecutive patients underwent SNB, followed by selective ND depending on the SNB status (“SNB group”). We excluded five patients, three in the first group, because either injection or lymphoscintigraphy was not performed, and two in the second group, because the tumor was micro-invasive. A total of 229 patients were followed, 50 from
Discussion
In this prospective cohort study with long-term follow-up, we evaluated the feasibility, reliability and accuracy of SNB in OSCC, and compared SNB to ND in terms of oncologic outcomes and morbidity. With a median follow-up of 5.6 years, the results of our study demonstrate that SNB is not detrimental to patient survival and is beneficial in terms of reduced morbidity.
SNB was an effective procedure, with a successful detection of SNs in over 93% of cases. Overall, there was no statistically
Conclusion
Patients having undergone SNB had significantly fewer complications compared to those with ND, with no late recurrences in long-term follow-up. Five-year RFT and OS were comparable between the two groups. SNB is a safe and effective procedure for managing T1/T2 cN0 OSCC, with completion ND only for patients with positive SNs. However, close follow-up is mandatory for SN+ patients, who are at higher risk of nodal recurrence and have worse prognosis.
Conflict of interest statement
None declared.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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