Skull base tumor volume and surgical margins: a pilot study

The relationship between preoperative assessment of tumor volume and oncologic adequacy of surgical margins was studied retrospectively. Our hypothesis was that the risk of inadequate, or positive, margins would rise with increasing tumor volume and that this would adversely affect survival. We anticipated that limitations of surgical approaches used until 1988 would be reflected in an increasing proportion of positive margins with increasing tumor volume. We conducted a pilot study of 25 patients with malignant tumors of the anterolateral cranial base operated on at the University of Pittsburgh Center for Cranial Base Surgery between 1987 and 1988. Preoperative computed tomography assessment of tumor volume was performed in all patients, and correlation between tumor volume, surgical margins, and survival was examined. Follow-up interval averaged 31.7 months. Twelve histologic tumor types were represented, with squamous cell carcinoma the most common (eight patients [32%]). Tumor volume ranged from 0.9 to 390 cc, with a median of 48 cc. Based on a median split of tumor volumes, patients were classified as high volume (more than 48 cc) or low volume (less than 48 cc). Of patients in the high volume group, 92% were found to have positive surgical margins, whereas only 50% of patients in the low volume group had positive margins. Analysis of the effect of tumor volume and surgical margins on survival was limited by sample size constraints, but both high-tumor volume and positive margins tended to reduce patient survival (0.07 < p 0.10).