Multifocal renal cortical tumors: frequency, associated clinicopathological features and impact on survival

We determined the frequency of tumor multifocality in patients with renal cortical tumors, characterized clinical and pathological features associated with multifocality and evaluated its effect on patient survival.

Between July 1989 and July 2002, 1,071 radical nephrectomies were performed at our institution. Specimens were examined grossly and microscopically for multifocal tumors. Preoperative imaging was reviewed to determine whether multifocality was suspected prior to operation. Multivariate analysis was performed to identify clinical and pathological factors associated with multifocality.

Of 1,071 radical nephrectomy specimens 57 (5.3%) had pathological evidence of tumor multifocality. Bilateral synchronous renal cortical tumors were present in 6 of the 57 multifocal cases (11%). A total of 19 cases (33%) had evidence of multifocality on preoperative imaging and, therefore, occult multifocality undetected on preoperative imaging was present in 3.5% of radical nephrectomies (38 of 1,071). Primary tumors in the multifocal group were most commonly conventional clear cell carcinoma, followed by papillary carcinoma. Of multifocal cases 74% had the same histological subtype in all tumors. Multivariate analysis demonstrated that bilaterality, papillary subtype, advanced tumor stage and lymph node metastasis were associated with multifocality. At a median follow up of 40.5 months overall survival, disease-free survival, and disease-free probability were not significantly different between the multifocal and unifocal groups.

We report a 5.3% frequency of multifocal renal cortical tumors and a 3.5% frequency of clinically unsuspected multifocal tumors. Multifocality had no apparent effect on recurrence or survival in patients who underwent radical nephrectomy.