PET–CT Reveals Need For Neck Dissection In Head & Neck Cancer Patients

Positron emission tomography–computed tomography may reduce the need for neck dissection in patients undergoing adjuvant treatment for head and neck cancer

medwireNews: Imaging can guide the need for neck dissection in patients with Squamous cell carcinoma of the head and neck, say researchers who report the use of surveillance to be equally effective in patients with and without human papillomavirus (HPV)-associated malignancy.

As reported in The New England Journal of Medicine, the team used positron emission tomography–computed tomography (PET–CT)-guided surveillance to identify patients who had an incomplete or equivocal response 12 weeks after completing chemoradiotherapy and thus required neck dissection.

The 282 patients randomly assigned to the surveillance group had noninferior overall survival at 2 years compared with the 282 patients assigned to undergo planned neck dissection before or after chemoradiotherapy, despite neck dissection occurring in just 54 versus 221 patients.

Indeed, the 2-year overall survival rate slightly favoured surveillance, at 84.9% versus 81.5% for planned neck dissection. And the hazard ratio of 0.92 MET the prespecified definition of noninferiority for surveillance, with the 95% confidence interval ruling out an unfavourable difference of more than 4 percentage points, the authors report.

Hisham Mehanna, from the University of Birmingham in the UK, and fellow PET–NECK Trial Management Group investigators say that this remained true after considering gender, age, tumour characteristics and treatment schedules, and after adjusting for HPV p16 expression status.

“[O]ur trial may actually underestimate the benefit of PET-CT–guided surveillance in patients with head and neck cancer”, the authors suggest, noting that their protocol recommended neck dissection in patients with an equivocal response, defined as imaging-negative residual mass or mild tracer uptake in normal-sized nodes.

“However, a recent study suggests that nodal disease may take longer to involute in patients with HPV-positive disease”, they explain. “It is therefore conceivable that patients in our trial who had HPV-positive tumors and equivocal PET-CT findings (especially with enlarged nodes) at the 3-month assessment might have achieved a cure without neck dissection if they had undergone PET-CT at a later time."

Locoregional control at 2 years was reached by 91.9% of the surveillance group and 91.4% of the planned neck dissection group, although the researchers note that the 2-year rate was better in the neck dissection patients who underwent surgery after chemoradiotherapy than beforehand, at 94.8% versus 90.4%.

Nodal recurrence was reported in three surveillance patients and one planned dissection patient, while distant metastases were recorded in 21 and 23 patients, respectively.

Among patients who underwent surgery, the surveillance and planned neck dissection groups had comparable rates of surgical complications (42 vs 38%). Global health status scores showed a small difference between the groups at the 6-month check-up, in favour of surveillance, but this was lost after 2 years.

Most (84%) patients had oropharyngeal cancer and 75% tested positive for the HPV infection-associated protein p16. The majority of patients had nodal stage N2a (17%) or N2b (61%) disease, while the remainder had N2c or N3 tumours.

“Although 5 of the 9 patients with stage N3 disease in the PET-CT surveillance group had complete responses, extrapolation of a PET-CT–guided surveillance policy to this higher-risk group of patients cannot currently be justified because of the small number of such patients in the trial”, the researchers caution.

Reference

Mehanna H, Wong W-L, McConkey CC, et al. PET–CT surveillance versus neck dissection in advance head and neck cancer. New Engl J Med 2016; Advance online publication 23 March.DOI: 10.1056/NEJMoa1514493

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