Prognostic significance of parapharyngeal space venous plexus and marrow involvement: potential landmarks of dissemination for stage I-III nasopharyngeal carcinoma.

PURPOSE

To determine whether the parapharyngeal space venous plexus and marrow of the skull base bones are anatomic landmarks of the potential routes for the spread of disease for Stage I-III (American Joint Commission on Cancer 1997 staging system) nasopharyngeal carcinoma (NPC).

METHODS AND MATERIALS

A total of 364 patients with NPC were enrolled in this study. The selection criteria were Stage I-III disease and primary radiotherapy at our hospital between 1990 and 2001. All patients had undergone MRI to evaluate the head-and-neck tumors. Patients who had undergone inadequate radiotherapy at a dose of <60 Gy and/or preradiotherapy chemotherapy before the imaging evaluation were excluded from the study.

RESULTS

Of the 364 patients treated between 1990 and 2001, 163 (44.8%) had low-risk Stage I-III NPC (without parapharyngeal space extension or T3 disease). The 5-year distant metastasis-free survival rate, with and without adjuvant chemotherapy, was 97% and 96%, respectively. The remaining 201 patients had Stage II-III with parapharyngeal space extension or T3 disease. Their 5-year recurrence-free survival rate, with and without adjuvant chemotherapy, was 76.8% and 53.2% (p = 0.01), respectively.

CONCLUSION

Our findings suggest that the risk of distant metastasis in Stage I-III NPC patients without parapharyngeal space extension or T3 disease is extremely low. Invasion into the parapharyngeal space venous plexus and marrow of the skull base bones is associated with distant metastasis, and involvement of these anatomic sites is considered a potential route for hematogenous disease spread in patients with Stage I-III NPC.