Volume-weighted mean nuclear volume in renal cell carcinoma

Tumor grade and stage are the most important prognostic parameters for renal cell carcinoma (RCC). The value of histologic nuclear grading, however, is impaired by the inconsistency of pathologists' observations. Estimate of volume-weighted mean nuclear volume (MNV), based on a stereologic method, is correlated with prognosis of bladder, prostate, and endometrial cancer. In this study, we investigated the prognostic value of stereologic estimation of nuclear volume in RCC.

This study included 62 patients with RCC who underwent radical nephrectomy between 1989 and 1996. Patients were evaluated in two groups: patients with locally advanced and/or metastatic disease were part of the poor prognosis group and patients with localized disease were part of the good prognosis group. Unbiased estimates of MNV were compared with histologic grade, tumor stage, and growth pattern according to Thoenes classification. Group means were compared using the nonparametric Kruskal-Wallis one-way analysis of variance. Univariate analysis of the data was performed for MNV and time to death, metastasis, local recurrence, and disease-free survival by paired sample t test. For categorical variables, Pearson's correlation test was used for statistical analysis.

There was no correlation between MNV and patient sex, age, tumor stage, and growth pattern. MNV showed a trend to be higher in sarcomatoid and chromophilic cell types than in chromophobe and clear cell types (P < 0.05). MNV values were significantly higher with increasing grades but no MNV cutoff levels could be defined. The MNV values were not different between localized and locally advanced and/or metastatic disease.

Our results indicate that estimates of MNV are not useful for predicting disease outcome. Further studies are needed to set up reproducible intervals of tumor dedifferentiation that could be carried out in routine practice for predicting progression.