The prognostic value of the ratio of standard uptake value of lymph node to primary tumor before treatment of locally advanced nasopharyngeal carcinoma

BACKGROUND: To evaluate the prognostic value of the ratio of the standard uptake value of the lymph node and primary tumor before the treatment of locally advanced nasopharyngeal carcinoma and examine the prognostic value of the tumor metabolic parameters (SUVmax(,) MTV, and TLG) of the lymph node and primary tumor of locally advanced nasopharyngeal carcinoma. METHODS: A total of 180 patients with locally advanced nasopharyngeal carcinoma diagnosed pathologically from January 1, 2016 to December 31, 2018 were selected, and the MEDEX system was used to automatically delineate the SUVmax, MTV, and TLG of the lymph node metastases and nasopharyngeal carcinoma primary tumor. In addition, the ratio of LN-SUVmax (SUVmax of the lymph node metastases) to T-SUVmax (SUVmax of the nasopharyngeal carcinoma primary tumor) was calculated, and a ROC curve was drawn to obtain the best cut-off value. Kaplan–Meier and Cox regression models were used for survival and multivariate analyses, respectively. RESULTS: The median follow-up period for participants was 32 (4–62) months. Univariate analysis showed that age (P = 0.013), LN-SUVmax (P = 0.001), LN-TLG (P = 0.007) and NTR (P = 0.001) were factors influencing the overall survival (OS). Factors affecting local progression-free survival (LPFS) were LN-SUVmax (P = 0.005), LN-TLG (P = 0.003) and NTR (P = 0.020), while clinical stage (P = 0.023), LN-SUVmax (P = 0.007), LN-TLG (P = 0.006), and NTR (P = 0.032) were factors affecting distant metastasis-free survival (DMFS). Multivariate analysis showed that NTR was an independent influencing factor of OS (HR 3.00, 95% CI 1.06–8.4, P = 0.038), LPFS (HR 3.08, 95% CI 1.27–7.50, P = 0.013), and DMFS (HR 1.84, 95% CI 0.99–3.42, P = 0.054). Taking OS as the main observation point, the best cut-off point of NTR was 0.95. Kaplan–Meier results showed that the 3-year OS (97.0% vs 85.4%, χ(2) = 11.25, P = 0.001), 3-year LPFS (91.3% vs 82.1%, χ(2) = 4.035, P = 0.045), and 3-year DMFS (92.3% vs 87.9%, χ(2) = 4.576, P = 0.032) of patients with NTR < 0.95 were higher than those with NTR > 0.95. CONCLUSIONS: High NTR before treatment indicates a poor prognosis for patients with nasopharyngeal carcinoma. This can serve as a reference value for the reasonable treatment and prognosis monitoring of such patients.