Background: To assess the prognostic usefulness of the nuclear area index (NAI), a new nuclear morphometric parameter expressed as the mean nuclear area (MNA) ratio of cancer to normal transitional cells in patients with bladder cancer, who have undergone radical cystectomy.
Methods: Measurements of the nuclear areas of cancer and normal transitional cells were carried out on the histological slides of 73 patients with bladder cancer. The clinical usefulness of MNA, NAI, grade, and TNM categories for the prediction of the cause-specific survival of the patients was examined.
Results: The median values of MNA and NAI in the 73 patients were 39 micro m2 and 1.2, respectively. Cause-specific survival rates of the patients were calculated according to stage (T1-2 vs T3-4), grade (grade 2 vs grade 3), MNA (<39 micro m2 vs>/=39 micro m2) and NAI value (<1.2 vs>/=1.2). Using univariate analysis, all these parameters were statistically significant prognostic factors. However, by multivariate analysis, NAI was the only independent variable for the survival of the patients (P < 0.01). Cause-specific survival rates of patients with NAI values of less than 1.2 were significantly higher than those with NAI values of 1.2 or more, in both grade 2 and grade 3 tumors.
Conclusions: These results suggest that NAI could provide improved prognostic information for patients with bladder cancer.