There is an ongoing debate about the management of patients with oral cavity squamous cell carcinoma and clinically negative cervical lymph nodes. Some clinicians favour preventive elective neck dissection (END) which although is linked with favourable survival has an adverse effect on quality of life while others adopt a wait and watch policy.

The aim of this review was to compare the prognosis of elective neck dissection or wait and watch in oral cavity cancer patients with clinically negative cervical lymph nodes.

Methods

Searches were conducted in the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, the Chinese Biomedical Literature (CBM) Database and ClinicalTrials.gov databases. Randomised controlled trials (RCTs), controlled clinical trials (CCTs) and cohort studies comparing resection of primary site with elective neck dissection (END) with ablation of tumour alone without neck dissection for histologically diagnosed oral cavity squamous cell carcinoma (OCSCC) were considered. END was classified as radical neck dissection (RND), modified radical neck dissection (MRND) or selective neck dissection (SND) according to dissection range.

Two reviewers independently selected studies, extracted data and assessed study quality. Risk of bias was assessed using the Risk Of Bias In Nonrandomized Studies of Interventions (ROBINS-I) tool. The hazard ratio (HR) of the time-to-event data was extracted or estimated.

Results

• 35 studies (5 RCTs, 30 retrospective cohorts) involving 5,161 patients were included.
• 5 studies were considered to be at low risk of bias,2 a moderate risk and 21 a serious risk of bias.
• Meta-analyses (33 studies) showed END could significantly decrease neck recurrence relative risk (RR) = 0.45 (95%CI; 0.35 – 0.59).
• END also significantly increased disease-free survival, overall survival and disease-specific survival (see table).

	No of studies	Hazard Ratio (95%CI)
disease-free survival	13	0.55 (0.42-0.71)
overall survival	14	0.75 (0.64-0.86)
disease-specific survival	11	0.76 (0.61-0.94)

• The subgroup analysis showed that END could:-
  • decrease neck recurrence RR = 0.48 (CI; 0.34-0.67)
  • improve disease-free survival; Hazard ratio = 0.53 (CI; 0.36-0.78)

Conclusions

The authors concluded: –

END can decrease recurrence and improve survival time in patients with OCSCC in the early stages (cT1- 2N0M0), which is associated with a more favourable prognosis compared with WW. The survival benefits of END potentially overweigh the adverse impact on quality of life. More high-quality studies are still needed to make a solid conclusion, especially for patients with cT1N0M0.

Comments

Earlier this year we looked at another review comparing END with observation or therapeutic neck dissection (Dental Elf – 22^nd Feb 2019). That review only included RCTs and prospective studies in contrast to the current review which also includes retrospective studies. While some may argue that this makes use of all the available information data from retrospective studies is more susceptible to bias and a majority of the included retrospective cohorts in the review either provided inadequate information to make an assessment or were considered to be at serious risk of bias. In addition, while the 5 RCTs included in this review were considered by the authors to be at low risk of bias 2 of them  were considered to be at unclear risk and 2 at high risk by the Cochrane team who assessed them for their 2018 review of surgical approaches for  oral cancer  (Dental Elf – 14th Jan 2019).

In addition, the authors themselves highlight inconsistencies in the conduct and reporting quality of the studies and lack of detail in relation to demographic characteristics and adjuvant treatment modalities. Taking all these issues into consideration the findings of the review need to be viewed cautiously. This and other recent reviews have all recommended that more high quality well-reported trials are needed to provide greater clarity on the best surgical approaches for the management of OCSCC.

Links

Primary Paper

Cao Y, Wang T, Yu C, Guo X, Li C, Li L. Elective Neck Dissection Versus Wait-and-Watch Policy for Oral Cavity Squamous Cell Carcinoma in Early Stage: A Systematic Review and Meta-Analysis Based on Survival Data. J Oral Maxillofac Surg. 2019 Mar 27. pii: S0278-2391(19)30340-4. doi:10.1016/j.joms.2019.03.015.[Epub ahead of print] PubMed PMID: 31014965.

Other references

Dental Elf – 22^nd Feb 2019

Oral Cancer: Elective or therapeutic neck dissection?

Dental Elf – 14th Jan 2019

Mouth and throat cancer: evidence for best surgical approaches uncertain