Future prognostic factors for renal cell carcinoma: Workgroup No. 5. Union Internationale Contre le Cancer (UICC) and the American Joint Committee on Cancer (AJCC)

Ki-67 and coagulative tumor necrosis are independent predictors of poor outcome for patients with clear cell renal cell carcinoma and not surrogates for each other

BACKGROUND

Ki-67 is a cell proliferation protein associated with aggressive clear cell renal cell carcinoma (ccRCC). A recent report suggests that Ki-67 may represent a surrogate marker for coagulative tumor necrosis. Thus, the goal was to directly test whether Ki-67 and necrosis convey similar or distinct information for the prognostic assessment of ccRCC.

METHODS

Tumor specimens from 741 consecutively treated patients who underwent surgery for ccRCC between 1990 and 1999 were evaluated. Tumor specimens were assessed for various clinicopathologic features, including levels of tumor cell Ki-67 expression. Associations of these features with death from RCC were evaluated using Cox proportional hazards regression models.

RESULTS

At last follow-up, 396 patients had died, including 238 who died from ccRCC at a median of 2.1 years after surgery. Although tumor cell Ki-67 expression and coagulative tumor necrosis were highly correlated, the prognostic information conveyed by these 2 markers failed to overlap. For the subset of patients with necrotic tumors, high levels of Ki-67 more than doubled the risk of death from RCC (risk ratio, 2.18; 95% confidence interval [CI], 1.52-3.11; P < .001). For patients with tumors lacking necrosis, high levels of Ki-67 expression were similarly correlated with an increased risk of death from RCC (risk ratio, 2.50; 95% CI, 1.66-3.77; P < .001).

CONCLUSIONS

Prognostic information conveyed by Ki-67 and coagulative tumor necrosis are not interchangeable. Thus, Ki-67 and coagulative tumor necrosis should not be treated as surrogates for one another and both of these features should be evaluated when generating outcome predictions for patients with ccRCC.

Prognostic Implications of the Immunohistochemical Expression of Human Kallikreins 5, 6, 10 and 11 in Renal Cell Carcinoma

Human kallikreins 5, 6, 10 and 11 (hK5, 6, 10 and 11) are expressed by many normal tissues, and it has been suggested that they may represent candidate tumor-diagnostic or -prognostic markers. In patients with renal cell carcinoma (RCC), outcome is unpredictable despite the use of conventional prognostic factors. The aim of this study is to evaluate the immunohistochemical expression and the prognostic value of the above kallikreins in RCC. The study comprised 95 patients who underwent radical nephrectomy for RCC. The median follow-up period was 60 months (range 1-180 months). Fifty-seven RCC cases were immunostained for hK5, 70 for hK6, 70 for hK10 and 69 for hK11. The streptavidin-biotin-peroxidase method of immunostaining was performed using anti-hK5, anti-hK6, anti-hK10 and anti-hK11 monoclonal and polyclonal antibodies. The immunohistochemical expression of these kallikreins was correlated with tumor size, histological type, histological malignancy according to the Fuhrman four-grade scale, mitotic index, pathological stage and disease survival. For the statistical analysis, four grades were collapsed into two by which RCC cases were categorized as low malignant (LM) and high malignant (HM). In the normal renal parenchyma adjacent to the tumors, the renal tubular epithelium showed a cytoplasmic expression of all four kallikreins. In RCC, immunohistochemical expression was decreased: 33 of 57 cases (58%) were positive for hK5, 27 of 70 (39%) for hK6, 46 of 70 (66%) for hK10 and 32 of 69 (46%) for hK11. A statistically significant positive correlation was observed among the immunohistochemical expression of all kallikreins. HM-RCC expressed all kallikreins in a higher percentage of cases than LM-RCC, but statistically significant differences were only observed for hK6 and hK10 (55 vs. 27%, p = 0.016, and 79 vs. 56%, p = 0.044, respectively). hK6 and hK11 expression showed a positive correlation to pathological stage: hK6 with both Robson and TNM 2002 staging systems (p = 0.010 and p = 0.017, respectively), and hK11 only with the Robson staging system (p = 0.045). In both the Kaplan-Meier and the univariate Cox regression analyses, hK6 expression was negatively correlated with disease-specific survival (p = 0.05 and p = 0.038, respectively). In univariate analysis, nuclear grade, Robson stage and TNM stage also correlated with disease-specific survival. However, in the multivariate analysis, TNM stage was the only independent prognostic factor. In conclusion, although the immunohistochemical expression of hK5, hK6, hK10 and hK11 was downregulated in RCC, tumors of high grade and late stage expressed one or more of the above kallikreins in a higher percentage of cases, and hK6 may predict a poor disease outcome in RCC.

Small renal cell carcinomas: correlation of size with tumor stage, nuclear grade, and histologic subtype

OBJECTIVE

Our goal was to correlate the size of renal cell carcinoma with tumor stage, nuclear grade, and histologic subtype in patients treated using partial or radical nephrectomy.

MATERIALS AND METHODS

We retrospectively reviewed 213 consecutive renal cell carcinomas resected at our institution from 1995 through 1999. Three groups of lesions stratified by size (< or = 3 cm, > 3-5 cm, > 5 cm) were compared with regard to pathologic findings. Statistical significance was assessed using Fisher's exact test.

RESULTS

Of 50 lesions 3 cm or smaller, 19 (38%) had extension outside the renal capsule (T3 or T4) and 14 (28%) were a high nuclear grade (Fuhrman grade 3 or 4). Lesions 3 cm or smaller and those greater than 3 cm to 5 cm did not differ statistically with regard to T stage or nuclear grade. Lesions larger than 5 cm showed a statistically higher T stage (p < 0.001) and nuclear grade (p = 0.001) than the other smaller lesions. More non-clear cell tumors were found in the two groups of smaller lesions (p = 0.105) but without statistical significance. The majority (58%) of the tumors were asymptomatic and had been detected incidentally on cross-sectional imaging. Lesions larger than 5 cm were significantly more likely to be symptomatic (p < 0.001). Seventy-nine percent of the tumors 3 cm or smaller were incidental, and these lesions did not differ significantly from the symptomatic lesions with regard to stage, grade, or histology.

CONCLUSION

In our study population, renal cell carcinomas up to 3 cm, including asymptomatic lesions, showed a significant incidence of high nuclear grade and tumor extension beyond the renal capsule; these findings support aggressive management of small lesions. Symptomatic status was not an adequate discriminator to guide management. A longitudinal study is necessary to further evaluate the efficacy of current patterns of therapy.

VHL mutations and their correlation with tumour cell proliferation, microvessel density, and patient prognosis in clear cell renal cell carcinoma

Mutations of the von Hippel-Lindau (VHL) gene are considered critical for the initiation of clear cell renal cell carcinoma. The VHL protein is involved in regulation of the cell cycle and neo-vascularization. In this study, the association of VHL mutations with tumour cell proliferation, angiogenesis, and clinical outcome was analysed in 113 clear cell renal cell carcinomas. The degree of angiogenesis and tumour cell proliferation was immunohistochemically determined by counting microvessels (microvessel density, anti-CD34 antibody) and cells with proliferating activity (Ki-67 labelling index, MIB-1 antibody). Forty-eight different VHL sequence alterations were found in 38 of 113 patients (34%) by direct sequencing. Nineteen VHL mutations were frameshifts and nonsense mutations, predicted to change the open reading frame of VHL. These 'loss-of-function' mutations correlated with worse prognosis in univariate analysis (p=0.02). Tumour grade, stage, microvessel density, and tumour cell proliferation were not associated with VHL alterations. These findings may indicate that 'loss-of-function' VHL mutations are involved in the progression of a clear cell renal cell carcinoma subset, whereas regulation of angiogenesis and proliferation of renal carcinoma in vivo is apparently not directly influenced by VHL alterations.