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Sentinel node biopsy achieved "oncological equivalence" with neck dissection in patients with operable T1-T2N0 oral and oropharyngeal cancer, researchers reported.

In a , the 2-year neck-relapse free survival (RFS) was 90.7% in the sentinel node (SN) biopsy group versus 89.4% in the neck dissection group, according to Renaud Garrel, MD, PhD, of Montpellier University Hospital Center in France.

That 1.1% difference fell well within the pre-specified 10% difference to determine if there was non-inferiority of SN biopsy to neck dissection, which is considered the standard of care for treatment of early stage head and neck cancers (P=0.008 for equivalence), he reported at the American Society of Clinical Oncology virtual meeting.

At 5 years, 89.4% of the SN biopsy group achieved neck-RFS versus 89.6% in the neck dissection group, he said in a pre-recorded oral presentation on the Senti-MER study.

Overall, there were 14 neck recurrences in 139 patients in the neck dissection group and 13 neck recurrences in 120 patients in the SN biopsy group.

Also, overall survival was 82.2% in the SN biopsy group and 81.8% in the neck dissection group.

Hisham Mehanna, MBChB, PhD, of the University of Birmingham and the Warwickshire Head and Neck Clinic in England, commented that "Elective neck dissection is the standard, especially for oral cancer. Sentinel node biopsy is an accepted technique as there have been large series that show benefit, but there has never been a head-to-head study with the standard of care."

Mehanna, who was not involved in the study, said that several questions remain: "Is sentinel node biopsy as effective as elective neck dissection, is it less morbid, and importantly, is it more cost-effective or as cost-effective, because sentinel node biopsy is resource intensive," he said.

"The study determined that sentinel node biopsy is non-inferior to elective neck dissection; it has equivalent recurrence-free survival; equivalent locoregional recurrence free survival; equivalent disease-specific recurrence free survival; and equivalent 2- and 5-year survival," Mehanna added. "It was also less morbid at the 2-, 4- and 6-month assessment point, but showed the same morbidity at 12 months. It also showed better function and less physiotherapy up to the 12-month assessment point and then it was the same as elective neck dissection."

He called the study a " significant achievement. We have been talking about it for a long time. So sentinel node biopsy should be considered a standard of care. It should be offered as an option alongside, or instead of, neck dissection." Mehanna added that "really data on cost-effectiveness will be important if this is going to be adopted widely because sentinel node biopsy is resource intensive and, in my mind, it is much easier just to do an elective neck dissection. Cost-effectiveness will remain an issue."

Garrel reported that cost-effectiveness is being assessed in an ancillary study.

For Senti-MER, 307 patients at 10 institutions were enrolled. After exclusions, 140 patients had SN biopsy and 139 had neck dissection. Patients were diagnosed with operable cT1-cT2NO oral or oropharyngeal squamous cell carcinomas, and had no history of head and neck surgery, neck surgery, or radiation therapy. Patients had to be able to receive transoral radiotracer injection for lymphoscintigraphy.

Garrel and colleagues found that morbidity was reduced among the patients undergoing SN biopsy. The median hospital stay was 1 day less in the SN biopsy group (P=0.001), while the mean hospital stay also was reduced (P=0.013).

He noted that physical problems in the arm were less common among the SN biopsy patients at the 2-, 4-, and 6-month assessment points, but the differences disappeared at 1 year. Similarly, SN biopsy patients required less physiotherapy at 2, 4 and 6 months, but the differences were not significant at 1 year.

"Senti-MER is a high level of evidence study," Garrel said. "It establishes that sentinel node [biopsy] is the standard of care among patients with T1-T2NO oral and oropharyngeal cancer."

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