A new classification for malignant tumors involving the anterior skull base

Objectives: To propose our clinical classification of malignant ethmoid tum ors and to compare it with the last American Joint Committee on Cancer (AJC C)-Union Internationale Contre le Cancer (UICC) classification, published i n 1997. Design: Retrospective review. Setting: Tertiary cancer facility. Patients: We evaluated 123 consecutive patients undergoing craniofacial res ection for malignant ethmoid tumors involving the anterior skull base. The mean follow-up was 60 months. Fifty-nine patients (48%) presented with recu rrent disease after prior therapy. We classified them with a new classifica tion system (Istituto Nazionale I)er lo Studio e la Cura dei Tumori) based on the most commonly accepted unfavorable prognostic factors (involvement o f dura mater; intradural extension; involvement of the orbit and, in partic ular. of its apex: invasion of maxillary, frontal, and/or sphenoid sinuses; and invasion of the infratemporal fossa and skin. We also classified patie nts with the AJCC classification published in 1997. Main Outcome Measures: Disease-free status and overall survival rate. To st udy a possible association with tumor stage, the Cox regression model was a dopted. Results: According to our classification, patient distribution by tumor typ e 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 surviva l 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 obta ined for overall survival. In contrast, patient distribution among differen t AJCC stages was less balanced, and we failed to detect a significant asso ciation with the clinical outcome using this classification. Conclusion: We propose the use of our staging system by all those specialis ts in the field willing to validate the classification and possibly apply i t for clinical and investigational purposes.