Oral cavity cancer is one of the most common cancers worldwide with about 90% being squamous cell carcinoma. Metastasis to the cervical lymph nodes is an important indicator of survival rate and there is a consensus that neck dissection must be considered when apparent node metastasis is identified clinically. However, for early-stage cancer with no neck nodes (NO) there is disagreement as to whether elective neck dissection (END) can avoid regional recurrence or if because this is an aggressive regime with complications such as, pain, shoulder dysfunction and contour changes preferring observation.
The aim of this review was to assess the possible benefits of elective neck dissection (END) in patients with squamous cell carcinoma (SCC) of the oral cavity and clinically N0 neck.
Searches were conducted in the Medline, Embase, the China National Knowledge Infrastructure, and the Wan Fang Databases with no restrictions on date or language. Prospective studies comparing END with observation or therapeutic neck dissection (TND) were considered. All patients had pathologically confirmed SCC of the oral cavity without clinically apparent metastasis of the cervical lymph node or distant metastases at the time of diagnosis. In addition, patients had not received previous antitumor treatment with the primary tumour being managed with surgery or radiotherapy.
Two reviewers independently selected studies with study quality being assessed using Cochrane risk of bias tool. Data was abstracted by a single reviewer and checked by a second reviewer. Outcomes were regional recurrences (cervical lymph node metastasis), specific death rate related to regional recurrences, occult cervical lymph node metastasis, and total number of recurrences. Meta-analysis was carried out.
- 6 studies (5 RCTs, 1 prospective randomised matched case-and-control study) involving 865 patients were included.
- 1 study was considered to be at low risk of bias and 5 at unclear risk.
- Regional recurrences
- 6 studies reported that regional recurrences were markedly decrease in END group compared to TND and observation.
- Meta-analysis (6 studies) showed END lowered risk of regional recurrences RR= 0.27 (95%CI; 0.21-0.36)
- Death rate related to regional recurrences (4 studies)
- 3 studies contributed to meta-analysis death rate was lower in the END group compared to TND and observation. RR= 0.35 (95%CI; 0.19 -0.65).
- Occult cervical lymph node metastasis (6 studies)
- Rates of occult metastasis in END group ranged from 20.59 to 49% (mean, 30.27%; standard deviation, 9.42%;
- Total number of recurrences (4 studies)
- Meta-analysis showed that the END group had a smaller total number of recurrences RR = 0.53 (95% CI; 0.44-0.64).
The authors concluded: –
this systematic review and meta- analysis suggests that END considerably decreases regional recurrences and the death related to it in early-stage oral SCC with clinically N0 neck, especially SCC of the oral tongue and floor of the mouth, confirming the necessity of END for these patients.
When considering the findings of this review the recent Cochrane review on surgical treatment of oral and oropharyngeal tumours should be taken into account (Dental Elf – 14th Jan 2019). That review had a broader scope than the current review which focuses on one aspect of the surgical approach. The Cochrane conclusions regarding the question posed by this review was
The evidence is insufficient to draw conclusions about END of clinically negative neck nodes at the time of removal of the primary tumour compared to TND.
Five out of the 6 studies included in this review were included in the Cochrane review. Interestingly while the Cochrane reviews scored 3 of the included trials the same two of the included studies were considered at high risk of bias by the Cochrane team. So while a small number of RCTs are available the quality of the available evidence is of very low quality so not sufficient to confirm which of these surgical approaches for the NO neck in oral cavity has the best outcomes.
Ding Z, Xiao T, Huang J, Yuan Y, Ye Q, Xuan M, Xie H, Wang X. Elective Neck Dissection Versus Observation in Squamous Cell Carcinoma of Oral Cavity With Clinically N0 Neck: A Systematic Review and Meta-Analysis of Prospective Studies. J Oral Maxillofac Surg. 2019 Jan;77(1):184-194. doi: 10.1016/j.joms.2018.08.007. Epub 2018 Aug 22. Review. PubMed PMID: 30218654.
Dental Elf – 14th Jan 2019
Mouth and throat cancer: evidence for best surgical approaches uncertain