To allow for an optimal balance between function and cancer cure, level 2b in selective neck dissection (SND) should be omitted when safe, according to a study published in Cancer.
The double-blind randomized controlled trial showed that 6 months after surgery, median shoulder-related quality of life (QOL) was 17 points lower than the baseline Neck Dissection Impairment Index (NDII), compared to 30 points lower with level 2b dissected. Even a minimal procedure of the spinal accessory nerve (SAN) resulted in patient-perceived shoulder impairment, but was not clinically significant until dissection of level 2b occurred.
“This study convincingly shows that SND (2a-4) causes less shoulder impairment than SND including 2b,” wrote Peter T. Dziegielewski, MD, and colleagues. “For patients with level 2b dissected (group 2), the decline was 30 points at 6 months, which is statistically and clinically significant.”
40 patients were enrolled and randomized in the study, with 30 included in the results. The patients were split into 2 groups (15 patients per group). Group 1 consisted of patients undergoing SND without level 2b dissection, while group 2 did not undergo level 2b dissection.
All patients completed NDII questionnaires pre- and postoperatively, with the 6-month postoperative score differences being statistically significant in both group 1 (P= .002) and 2 (P= .001). The group of patients also reported attending physical therapy sessions and completing at-home exercises.
“The dysfunction observed even with SND (2a-4) is potentially related to the partial devascularization of the SAN on the superior aspect of level 2a,” wrote the researchers. “It could also be due to an SAN injury when the level III/IV contents are pulled up under the [sternocelidomastoid muscle]. The SAN is in close proximity and can be grossly injured or overstimulated during this part of the dissection if the surgeon is not careful.”
After SND, all of the patients experienced decreases in self-perceived shoulder function. Further, none returned to baseline levels, although partial recovery occurred at 6 months. Even more, range of motion measures in group 1 and 2 declined from baseline to 6 months. The researchers determined the loss of active range of motion in the shoulder was due to losses in nerve function rather than mechanical contractures in the shoulder joint from level 2b dissection.
Limitations of the study included a low sample size of just 30 patients, while the recruitment of patients was challenging due to the strict criteria necessary for eligible patients. No adverse events were reported.
Further research should investigate different methods of level 2 and SAN dissection to learn more about different levels of nerve disruption. Moreover, future studies should consider following up with patients after 1 year or longer because of the possibility that shoulder QOL continues to improve past the amount of time the researchers examined (first 6 months).
“SND including level 2b leads to significant long-term deterioration in QOL and active abduction and nerve conduction amplitude deficiencies,” wrote the researchers. “When it is oncologically sound, level 2b should be omitted from SND.”
Dziegielewski P, McNeely ML, Ashworth N, et al. 2b or Not 2b? Shoulder Function After Level 2b Neck Dissection: A Double-Blind Randomized Controlled Clinical Trial. Cancer. 10.1002/cncr.32681.