Objectives: To determine the pathologic features, including histologic subtype and tumor size, associated with multifocal renal cell carcinoma (RCC) and the impact of multifocality on survival after radical nephrectomy, about which controversy exists.
Methods: We studied 2373 patients who underwent radical nephrectomy for RCC from 1970 to 2000. Histologic subtype, stage (2003 TNM), nuclear grade, tumor size, and multifocality, defined as the presence of more than one ipsilateral RCC tumor of the same histologic subtype, were evaluated. Associations of multifocality with ipsilateral and contralateral recurrence and death from RCC were evaluated using Cox proportional hazards models.
Results: The incidence of sporadic histologically concordant multifocality was greater in papillary RCC (29 of 266; 10.9%) compared with clear cell RCC (40 of 1934; 2.0%; P <0.001) and chromophobe RCC (2 of 104; 1.9%; P = 0.005). Patients with solitary clear cell and papillary RCC had larger tumors compared with multifocal clear cell and papillary RCC (P <0.001 and P = 0.024, respectively). Patients with multifocal clear cell RCC were more likely to have a contralateral recurrence than were patients with solitary clear cell RCC (risk ratio 2.91, P = 0.142). Multifocality was not significantly associated with ipsilateral recurrence or death from RCC in patients with clear cell or papillary RCC.
Conclusions: The incidence of multifocality was significantly greater among patients with papillary RCC than among patients with clear cell or chromophobe RCC. Patients with multifocal clear cell RCC were more likely to experience a contralateral recurrence. Multifocality was not significantly associated with ipsilateral recurrence or death from RCC. In addition, multifocality was not associated with larger and higher stage tumors, as previously reported.