Surgical treatments for mouth and throat cancer: uncertainty in the evidence

Oral cancer is among the most common cancers worldwide, with more than 400,000 new cases diagnosed in 2012. This review looks at oral cavity cancer (mouth cancer) and oropharyngeal cancer (throat cancer). The treatment of these cancers can involve surgery, chemotherapy, radiotherapy or a combination of two or all three therapies. This topic area was identified as a priority by the an expert working group for oral and maxillofacial surgery in 2014.

What was the research?

A systematic review to examine clinical trials of surgical treatments for oral and oropharyngeal cancers to find out which were most likely to result in people with these cancers living longer (overall survival) and living longer without symptoms (disease-free survival). We also wanted to find out how different treatments affect disease symptoms, quality of life, time in hospital, complications, side effects and cost.

Who conducted the research?

The research was conducted by a team led by Vishal M. Bulsara of the University of Western Australia, Australia, on behalf of Cochrane Oral Health. Helen V. Worthington, Anne-Marie Glenny, Janet E. Clarkson, David I. Conway and Michaelina Macluskey were also on the team.

What evidence was included in the review?

We included 12 randomised controlled trials, including 2,300 participants. The trials included seven comparisons of different treatment options. None of them compared different surgical approaches for cutting out the primary tumour.

What did the evidence say?

The findings of the studies are mixed and it is not possible to draw firm conclusions about the optimal surgical approach for mouth and throat cancers. Surgical removal of the lymph nodes in the neck that appear to be cancer‐free, at the same time as the cancer is removed, did not seem to be associated with longer survival in two studies whose results were combined. Another study, however, suggested there may be a benefit of early neck surgery in terms of overall survival and ‘disease‐free survival’ (length of time after primary treatment without signs and symptoms of disease). One study found cancer recurrence at or around the same site was less likely with the early surgery, while three other studies did not favour either treatment.

There was no evidence that removal of all the lymph nodes in the neck resulted in longer survival compared to selective surgical removal of affected lymph nodes.

One study evaluated use of a special scan (positron‐emission tomography‐computed tomography (PET‐CT)), after a combination of chemotherapy and radiotherapy, to guide decisions about neck dissection, and found no difference in mortality (death) compared with undertaking a planned neck dissection before or after chemoradiotherapy.

There were a number of other surgical approaches compared in the studies, but we were unable to use the results in this review.

Although removal of lymph nodes from the neck is known to be associated with significant negative effects related to appearance and functions such as eating, drinking and speaking, the studies reported poorly on these side effects and did not measure quality of life accurately enough or in large enough numbers to be included in any of our analyses.

How good was the evidence?

The certainty of the evidence was very low as there were few studies for each comparison and they were at risk of bias because of the way they were designed. Some comparisons and outcomes had no useable results.

What are the implications for doctors and the general public?

This review includes 12 randomised controlled trials that evaluated neck dissection surgery in participants with oral cavity cancers. We found insufficient evidence to draw conclusions about elective neck dissection of clinically negative neck nodes at the time of removal of the primary tumour compared to therapeutic neck dissection. Two studies using radical neck dissection as the elective procedure did not find a difference between interventions, while one trial found that elective supraomohyoid neck dissection may be associated with increased overall and disease‐free survival when compared to a therapeutic neck dissection. Three studies had inconclusive results for locoregional recurrence, and one found this was reduced with elective neck dissection. There is no evidence that elective radical neck dissection increases overall survival compared to more conservative neck dissection surgery. There is no evidence of a difference in mortality between PET‐CT surveillance following chemoradiotherapy versus planned ND (before or after chemoradiotherapy). Reporting of adverse events in all trials was poor and it was not possible to compare the quality of life of participants undergoing different surgeries. Available evidence for all comparisons and outcomes is very low certainty and results should be interpreted in light of this.

What should researchers look at in the future?

We would make the following recommendations for future research involving the surgical treatment of oral or oropharyngeal tumours.

  • Trialists are encouraged to follow the CONSORT guidelines when reporting on their trials. Ideally, trials should report hazard ratios with 95% confidence intervals for survival data, or present data that allows for the calculation of this estimate of effect.
  • Health-related quality of life is an important outcome measure that should be integral to all trials of oral cavity and oropharyngeal cancers.
  • There should be a standardised and consistent reporting of adverse events and morbidity associated with treatment, with results reported per participant.
  • Future trials of oral cavity and oropharyngeal cancers should report data based on the location of the primary tumour.

Link

Bulsara  VM, Worthington  HV, Glenny  AM, Clarkson  JE, Conway  DI, Macluskey  M. Interventions for the treatment of oral and oropharyngeal cancers: surgical treatment. Cochrane Database of Systematic Reviews 2018, Issue 12. Art. No.: CD006205. DOI: 10.1002/14651858.CD006205.pub4.

This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Editorial Base.