Locoregional extension and patterns of failure for nasopharyngeal carcinoma with intracranial extension.

OBJECTIVE

To evaluate the locoregional extension and patterns of failure for nasopharyngeal carcinoma (NPC) with intracranial extension to improve clinical target volume (CTV) delineation.

PATIENTS AND METHODS

A total of 205 NPC patients with intracranial extension by magnetic resonance imaging (MRI) were retrospectively reviewed.

RESULTS

According to the cumulative incidence rates of tumor invasion, we initially classified anatomic sites surrounding the nasopharynx into three risk grades: high risk (≥35%), medium risk (≥10-35%), and low risk (<10%). It was concluded that the anatomic sites at high risk of tumor invasion were the middle/posterior skull base and the anatomic sites adjacent to the nasopharynx. The rate of lymph node (LN) metastasis was 90.2% (185/205). Retropharyngeal region (RP) and level IIb were the most frequently involved regions. Skip metastasis occurred in only 1.6% (3/185). At their last follow-up visit, 53 patients (25.9%) had developed treatment failure. Of the 18 local failures, 12 were considered in-field failure; the other 5 were marginal; one of the patients had outside-field failure. Among the 5 patients with marginal failures, 4 occurred mainly intracranially, and 1 occurred in the floor and the left lateral wall of the nasopharynx. Of the 11 regional failures, 10 were considered in-field failures and most of them (8/10) occurred in the unilateral upper neck.

CONCLUSION

For NPC with intracranial extension, primary disease and regional LN spread follow an orderly pattern and LN skipping was unusual. Clinical target volume reduction may be feasible for selected patients.