Larger lymph node threshold helps facilitate better risk stratification and treatment decisions in nasopharyngeal carcinoma

Reviewed by Megan Craig, M.Sc.Sep 29 2023

According to the American Journal of Roentgenology (AJR), using a 6-mm threshold, rather than a 5-mm threshold, helps facilitate better risk stratification and treatment decisions in patients with nasopharyngeal carcinoma (NPC).

Future American Joint Committee on Cancer (AJCC) staging updates should consider incorporation of the 6-mm threshold for N-category and tumor-stage determinations."

Zhiying Liang, MD, corresponding author from the radiology department at China's Sun Yat-sen University Cancer Center

This AJR accepted manuscript by Liang et al. included 1,752 patients (median age, 46 years; 1,297 men, 455 women) with NPC treated by intensity-modulated radiotherapy from January 2010 to March 2014 from two hospitals; 438 patients underwent MRI 3-4 months after treatment. Two radiologists measured the minimal axial diameter (MAD) of the largest retropharyngeal lymph node (RLN) for each patient via consensus. Then, to assess interobserver agreement, a third radiologist measured MAD in 260 randomly selected patients. Initial ROC and restricted cubic spline analyses were used to derive an optimal MAD threshold for predicting progression-free survival (PFS).

Ultimately, in patients with NPC, overall survival was significantly different between patients with stage-I and stage-II disease defined using a 6-mm threshold (p = .04)-;but not using a 5-mm threshold (p = .09). The 5-year PFS rate was associated with post-radiotherapy MAD ≥ 6 mm (HR = 1.68, p = .04) but not with post-radiotherapy MAD ≥ 5 mm (HR = 1.09, p = .71).

"Given the absence of a defined size threshold in the AJCC 8th edition staging manual," the AJR authors noted, "we propose that future updates to the manual incorporate this threshold for N-category and tumor-stage determinations."