How accurate is diagnostic imaging in determination of size and multifocality of renal cell carcinoma as a prerequisite for nephron-sparing surgery?

Background: The indication for elective nephron-sparing surgery (NSS) in renal cell carcinoma (RCC) is under discussion in the urological literature. The main problem of NSS is the multifocality of RCC. The presented study was preformed to assess the accuracy of pre-and intraoperative ultrasound (US), and computerized tomography (CT) in determination of tumor size and detection of multifocal lesions. als and methods: Tumor size was measured by preoperative US and CT and compared with the tumor diameters in gross sections of the neoplastic kidneys. Multifocality was determined by 3-mm step sectioning of the nephrectomy specimen, and the results were correlated with preoperative US and CT on the one hand, and the ex situ sonography of the nephrectomized kidney on the other hand. s: US and CT show similar results in the determination of the tumor size. In only 22.9%, preoperative US and CT were able to detect multifocal tumors. Ex situ sonography had a sensitivity of 40.0% and a specificity of 87.2% in this regard. sions: In preparation for nephron-sparing surgery of renal cell carcinoma, neither preoperative routine imaging, nor intraoperative ultrasound can safely predict multifocal lesions of renal cell carcinoma. tary tumor recurrence following nephron-sparing surgery (NSS) for renal cell carcinoma (RCC) may be due to incomplete resection of the primary tumor, occult multicentric disease or the development of a new primary or metastatic focus of RCC in the renal remnant. The risk of multicentric disease in RCC has been evaluated and debated extensively in the literature. RCC generally occurs as a discrete focal lesion rather than an infiltrative process which is seen in carcinoma of the prostate. At issue is whether the molecular events that give rise to malignant transformation affect a discrete segment of the kidney or a broader segment of the renal tubular epithelium. A high incidence of multicentric RCC has been reported in patients with germ line mutations such as those that exist in von Hippel Lindau disease and other forms of hereditary RCC suggesting a global predisposition to malignant degeneration throughout the entire renal parenchyma. cidence of multicentricity in sporadic RCC has been less clear. Emerging cytogenetic and molecular data suggest that satellite lesions may occasionally arise from the same malignant clone as their corresponding primary lesion and may therefore represent biologically significant intra-renal metastasises. A recent review of published studies comprising over 1100 cases of sporadic RCC indicated an aggregate incidence of 15.2% of tumor multifocality (range 6.5%–28%)[1]. It is important to remember that these studies represent a diverse group of patients and that RCC is in fact a heterogenous group of tumors. The risk of multicentricity is not equal in all patients and appears to be related to other prognostic variables such as tumor histology, stage and grade. For example, papillary RCC is known to be associated with a higher incidence of multifocality than the more common clear cell variant. The risk of multifocal disease also increases with larger tumors, particularly those that extend beyond the renal capsule (pT3+). Finally, some microfocal tumors are of unknown biological significance such as the finding of satellite adenomas. Of importance when considering relative indications for elective NSS is the incidence of multifocality when the primary or index tumor is ⩽ 4 cm. A recent review of the literature indicated that the incidence of multifocality in this setting is approximately 5%. st worrisome implication of multifocal RCC is that this will predispose to an increased risk of local tumor recurrence following NSS. Although this potential risk must be considered, the relationship between multifocality and local recurrence is neither linear or predictable as suggested by the low overall local recurrence rates reported following NSS in several large series. In nearly 1800 cases of NSS reported in the literature to date, the risk of local tumor recurrence has ranged from 0–10% and is clearly lowest among patients undergoing elective NSS for small (⩽ 4 cm) low stage lesions [1]. The true biologic significance of multicentric renal tumors and their implication for NSS therefore remain to be fully elucidated. zo RG, Novick AC. Nephron-sparing surgery for renal tumors: indications, techniques and outcomes. J Urol 2001;166:6–18. C. Novick, M.D.