Prognostic factors and failure patterns in non-metastatic nasopharyngeal carcinoma after intensity-modulated radiotherapy

Abstract

BackgroundThe prognostic values of staging parameters require continual re-assessment amid changes in diagnostic and therapeutic methods. This study aimed to identify the prognostic factors and failure patterns of non-metastatic nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era.MethodsWe reviewed the data from 749 patients with newly diagnosed, biopsy-proven, non-metastatic NPC in our cancer center (South China, an NPC endemic area) between January 2003 and December 2007. All patients underwent magnetic resonance imaging (MRI) before receiving IMRT. The actuarial survival rates were estimated using the Kaplan–Meier method, and survival curves were compared using the log-rank test. Multivariate analyses with the Cox proportional hazards model were used to test for the independent prognostic factors by backward eliminating insignificant explanatory variables.ResultsThe 5-year occurrence rates of local failure, regional failure, locoregional failure, and distant failure were 5.4, 3.0, 7.4, and 17.4%, respectively. The 5-year survival rates were as follows: local relapse-free survival, 94.6%; nodal relapse-free survival, 97.0%; distant metastasis-free survival, 82.6%; disease-free survival, 75.1%; and overall survival, 82.0%. Multivariate Cox regression analysis revealed that orbit involvement was the only significant prognostic factor for local failure (P = 0.011). Parapharyngeal tumor extension, retropharyngeal lymph node involvement, and the laterality, longest diameter, and Ho’s location of the cervical lymph nodes were significant prognostic factors for both distant failure and disease failure (all P < 0.05). Intracranial extension had significant prognostic value for distant failure (P = 0.040).ConclusionsThe key failure pattern for NPC was distant metastasis in the IMRT era. With changes in diagnostic and therapeutic technologies as well as treatment modalities, the significant prognostic parameters for local control have also been altered substantially.

High COX‐2 expression in cancer‐associated fibiroblasts contributes to poor survival and promotes migration and invasiveness in nasopharyngeal carcinoma

“…Most distant metastasis occurs within 3 years after radiotherapy completion, with distant metastasis occurring in 52% of patients in the 1st year, 23% in the 2nd year, and 20% in the 3rd year . To date, although NPC is sensitive to radiotherapy, distant metastasis is the primary cause of treatment failure …”

The development and external validation of simplified T category classification for nasopharyngeal carcinoma to improve the prognostic value in the intensity‐modulated radiotherapy era

“…In the 2D‐CRT era, patients with orbit, cranial nerve, intracranial, or medial and lateral pterygoid muscle involvement have poor prognoses, and were classified as T4 disease according to the 7th AJCC staging system . However, only orbit involvement remains a significant prognostic factor for local failure in the IMRT era . Pan et al conducted a retrospective study of 1609 patients with NPC who were staged using MRI and observed no significant differences in OS among those with infiltration of adjacent soft tissues, including the medial and lateral pterygoid muscles, prevertebral muscles and parapharyngeal space .…”

“…Lai et al found the improved treatment outcomes for patients treated with IMRT compared to 2D-CRT were primarily due to higher local tumor control, and also demonstrated distant metastasis is now the predominant mode of treatment failure in NPC. 6,19 Hen et al reported that T category had no predictive value for local control and OS, whereas N category was a significant prognostic factor for OS. 19 Therefore, the prognostic value of T category may have become weaker than that of N category due to the excellent local control rates.…”

“…During the study, institutional guidelines recommended only IMRT for stage I NPC and IMRT combined with concurrent chemoradiotherapy ± neoadjuvant/adjuvant chemotherapy for stage II to IVa NPC. When possible, salvage treatments (intracavitary brachytherapy, surgery, or chemotherapy) were provided for patients with documented relapse or persistent disease …”

“…When possible, salvage treatments (intracavitary brachytherapy, surgery, or chemotherapy) were provided for patients with documented relapse or persistent disease. 6…”