In search of a better crystal ball: recent advances in prognostic markers for clear-cell renal cell carcinoma

Molecular imaging of urogenital diseases

There is an expanding and exciting repertoire of PET imaging radiotracers for urogenital diseases, particularly in prostate cancer, renal cell cancer, and renal function. Prostate cancer is the most commonly diagnosed cancer in men. With growing therapeutic options for the treatment of metastatic and advanced prostate cancer, improved functional imaging of prostate cancer beyond the limitations of conventional CT and bone scan is becoming increasingly important for both clinical management and drug development. PET radiotracers, apart from ¹⁸F-FDG, for prostate cancer are ¹⁸F-sodium fluoride, ¹¹C-choline, and ¹⁸F-fluorocholine, and (¹¹C-acetate. Other emerging and promising PET radiotracers include a synthetic l-leucine amino acid analogue (anti-¹⁸F-fluorocyclobutane-1-carboxylic acid), dihydrotestosterone analogue (¹⁸F-fluoro-5α-dihydrotestosterone), and prostate-specific membrane antigen-based PET radiotracers (eg, N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-4-¹⁸F-fluorobenzyl-l-cysteine, ⁸⁹Zr-DFO-J591, and ⁶⁸Ga [HBED-CC]). Larger prospective and comparison trials of these PET radiotracers are needed to establish the role of PET/CT in prostate cancer. Although renal cell cancer imaging with FDG-PET/CT is available, it can be limited, especially for detection of the primary tumor. Improved renal cell cancer detection with carbonic anhydrase IX (CAIX)-based antibody (¹²⁴I-girentuximab) and radioimmunotherapy targeting with ¹⁷⁷Lu-cG250 appear promising. Evaluation of renal injury by imaging renal perfusion and function with novel PET radiotracers include p-¹⁸F-fluorohippurate, hippurate m-cyano-p-¹⁸F-fluorohippurate, and rubidium-82 chloride (typically used for myocardial perfusion imaging). Renal receptor imaging of the renal renin-angiotensin system with a variety of selective PET radioligands is also becoming available for clinical translation.

Proteomic identification of Reticulocalbin 1 as potential tumor marker in renal cell carcinoma

Renal cell carcinoma (RCC) biomarkers are necessary for diagnosis and prognosis. They serve to monitor therapy response and follow-up, as drug targets, and therapy predictors in personalized treatments. Proteomics is a suitable method for biomarker discovery. Here we investigate differential protein expression in RCC, and we evaluate Reticulocalbin 1 (RCN1) use as a new potential marker. Neoplastic and healthy tissue samples were collected from 24 RCC patients during radical nephrectomy. Seven specimens were firstly processed by proteomic analysis (2-DE and MALDI-TOF) and 18 differentially expressed proteins from neoplastic and healthy renal tissues were identified. Among them, RCN1 was over-expressed in all cancer specimens analyzed by proteomics. Consequently RCN1 use as a potential marker was further evaluated in all 24 donors. RCN1 expression was verified by Western blotting (WB) and immunohistochemistry (IHC). WB analysis confirmed RCN1 over-expression in 21 out of 24 tumor specimens, whereas IHC displayed focal or diffuse expression of RCN1 in all 24 RCC tissues. Thus RCN1 appears as a potential marker for clinical approaches. A larger histopathological trial will clarify the prognostic value of RCN1 in RCC.

BIOLOGICAL SIGNIFICANCE

The present work aimed at finding new biomarkers for RCC - a life-threatening disease characterized by high incidence in Western countries - by performing differential proteomic analysis of neoplastic and normal renal tissues obtained from a small cohort of RCC patients. Some of the identified proteins have been previously associated to renal cancer however data confirming the possible use of these proteins in clinical practice are not available to date. By IHC we demonstrated that RCN1 could be easily employed in clinical practice, confirming RCN1 over-expression in RCC tissues of all examined patients, and weak protein expression in healthy renal tissues only in correspondence to the renal tubule section. These data indicate a promising role of RCN1 as a possible marker in RCC and indicate the proximal convoluted renal tubule as a putative origin point for RCC. Since IHC staining displayed different grades of intensity in tested tissues, we hypothesized that RCN1 could also be employed as a prognostic marker or as a response predictor for RCC-targeted therapy. To test such a hypothesis, a larger retrospective trial on paraffin-embedded tissues obtained from radical or partial nephrectomy of RCC patients is planned to be performed by our group.

Racial disparity in renal cell carcinoma patient survival according to demographic and clinical characteristics

BACKGROUND

Patients with renal cell carcinoma (RCC) who are black tend to have poorer prognosis than similar patients who are white. This study examined whether the racial disparity in RCC patient survival varies by demographic and clinical characteristics.

METHODS

Nearly 40,000 patients (4359 black and 34,991 white) diagnosed with invasive RCC from 1992 to 2007 were identified from 12 registries in the National Cancer Institute Surveillance, Epidemiology, and End Results program, covering approximately 14% of the US population. Relative survival rates through 2008 were computed using the actuarial method.

RESULTS

Proportionally more blacks than whites were diagnosed with RCC under age 50 and with localized cancer. Overall, the 5-year relative survival rates were 72.6% (95% confidence interval 72.0%-73.2%) for white and 68.0% (66.2%-69.8%) for black patients. Survival was higher among women than men and among younger than older patients. Survival decreased with advancing tumor stage and, within each stage, decreased with increasing tumor size. Patients with clear cell RCC, a more common form among whites, had poorer prognosis than patients with papillary or chromophobe subtypes, which are more common among blacks. Survival for patients who received no surgical treatment (10.5% of white patients and 14.5% of black patients) was substantially lower than for patients treated with nephrectomy, with similar survival among whites and blacks. In all other demographic and clinical subgroups of patients, whites consistently had a survival advantage over blacks.

CONCLUSIONS

Patients with RCC who are white consistently have a survival advantage over those RCC patients who are black, regardless of age, sex, tumor stage or size, histological subtype, or surgical treatment.

Kidney size and cancer-specific survival for patients undergoing nephrectomy for pT1 clear cell renal cell carcinoma

OBJECTIVE

To examine the association between kidney size and renal cell carcinoma (RCC) death among patients with Stage pT1 clear cell RCC undergoing surgery.

METHODS

We used a case-cohort design and evaluated 191 patients from our Nephrectomy Registry who had undergone open radical nephrectomy for unilateral, sporadic, Stage pT1N0/NxM0, noncystic clear cell RCC from 1989 to 2004. Of these, 47 patients died of RCC ("cases") and 144 patients were alive at the last follow-up visit or had died of other causes ("cohort"). Univariate and multivariate associations with RCC death were evaluated using weighted Cox regression analysis and summarized with hazard ratios and 95% confidence intervals.

RESULTS

The median kidney size was 12 cm. We observed a positive association between increasing kidney size and the risk of RCC death. A 1-cm increase in kidney size was associated with an 18% increased risk of RCC death, even after adjusting for tumor size, nuclear grade, and the presence of necrosis. After multivariate adjustment, those patients with a kidney size greater than the median were 95% more likely to die of RCC than those with a kidney size less than the median (hazard ratio 1.95, 95% confidence interval 1.00-3.81; P = .05). The limitations of our study included a lack of data on the 3-dimensional kidney volume and an inability to generalize to patients with larger tumors (ie, Stage pT2) or other RCC subtypes.

CONCLUSION

Our data suggest that kidney size is an independent predictor of survival for patients with Stage pT1 clear cell RCC. Future investigations are needed to confirm this finding and investigate this issue in larger, organ-confined tumors and other RCC subtypes.

Three-dimensional tumour volume and cancer-specific survival for patients undergoing nephrectomy to treat pT1 clear-cell renal cell carcinoma

Study Type - Prognosis (case series) Level of Evidence 4. What's known on the subject? and What does the study add? The positive association of tumour size (largest tumour dimension on pathology review) and risk of RCC progression and survival following nephrectomy is well documented. Moreover, several clinicopathological scoring systems (i.e. nomograms and algorithms) have been developed to predict outcomes for surgically treated RCC patients and each of these includes tumour size as an independent predictor of RCC outcome. There is still the question of whether information on three-dimensional tumour volume (cm(3) ) can provide additional prognostic information, particularly among patients with small pT1 tumours where the range of tumour size is more limited. Our study demonstrates that increasing tumour volume is associated with a greater risk of RCC-specific death in patients with pT1 ccRCC, with a more pronounced association in pT1a tumours specifically. In addition, we observed evidence that tumour volume may provide more accurate prognostic information than tumour size alone in pT1a patients. Tumour volume may add prognostic information specifically in pT1a RCC.

OBJECTIVE

To address whether information on three-dimensional tumour volume can provide additional prognostic information for patients with small, localized renal cell carcinoma (RCC) superior to tumour size alone.

PATIENTS AND METHODS

We identified 955 patients treated with radical nephrectomy or nephron-sparing surgery for unilateral, sporadic, pT1, pN0/NX, M0, non-cystic clear-cell RCC (ccRCC) between 1980 and 2004, including 515 pT1a patients and 440 pT1b patients. • We estimated tumour volume using three tumour dimensions recorded on pathological analysis and the equation for the volume of an ellipsoid [π/6 (length × width × height)]. For tumour size alone, we used the maximum tumour diameter recorded on pathological analysis. • Univariate and multivariable associations with RCC-specific death were evaluated using Cox proportional hazards regression models summarized with hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Among pT1a patients, the risk of RCC death associated with having a tumour volume above the median (HR = 4.55; 95% CI, 1.30-15.83; P= 0.018) was markedly higher than having a tumour size above the median (HR = 2.55; 95% CI 0.83-7.85; P= 0.10). Comparison of concordance (c) index values further supported the idea that additional prognostic information was provided by tumour volume (c= 0.659) compared with tumour size (c= 0.600) for pT1a patients. • Among pT1b patients, we noted that associations of tumour volume and tumour size with RCC-specific death were similar. • Multivariable adjustment did not alter our findings.

CONCLUSIONS

Tumour volume could provide valuable prognostic information for patients with pT1a ccRCC but not pT1b ccRCC. • Future investigations are needed to confirm this finding, explore other RCC subtypes and evaluate accuracy of tumour volume determination on radiographic imaging for potential patient management before surgery.