A new classification for malignant tumors involving the anterior skull base

To propose our clinical classification of malignant ethmoid tumors and to compare it with the last American Joint Committee on Cancer (AJCC)-Union Internationale Contre le Cancer (UICC) classification, published in 1997.

Retrospective review.

Tertiary cancer facility.

We evaluated 123 consecutive patients undergoing craniofacial resection for malignant ethmoid tumors involving the anterior skull base. The mean follow-up was 60 months. Fifty-nine patients (48%) presented with recurrent disease after prior therapy. We classified them with a new classification system (Istituto Nazionale per lo Studio e la Cura dei Tumori) based on the most commonly accepted unfavorable prognostic factors (involvement of dura mater; intradural extension; involvement of the orbit and, in particular, of its apex; invasion of maxillary, frontal, and/or sphenoid sinuses; and invasion of the infratemporal fossa and skin. We also classified patients with the AJCC classification published in 1997.

Disease-free status and overall survival rate. To study a possible association with tumor stage, the Cox regression model was adopted.

According to our classification, patient distribution by tumor type was T2, n = 46; T3, n = 29; and T4, n = 48 (no T1 tumors were present in the series). For previously untreated patients, 5-year disease-free survival estimates were T2, 57%; T3, 50%; and T4, 13%. For relapses, corresponding figures were T2, 31%; T3, 23%; and T4, 1%. The prognostic difference among stages was statistically significant (P<.001). Similar results were obtained for overall survival. In contrast, patient distribution among different AJCC stages was less balanced, and we failed to detect a significant association with the clinical outcome using this classification.

We propose the use of our staging system by all those specialists in the field willing to validate the classification and possibly apply it for clinical and investigational purposes.