Prognostic factors and prognostic models for renal cell carcinoma: a literature review

There are no robust data on prognostic factors for overall survival (OS) in patients with metastatic renal cell carcinoma (RCC) treated with vascular endothelial growth factor (VEGF) -targeted therapy. Baseline characteristics and outcomes on 645 patients with anti-VEGF therapy-naïve metastatic RCC were collected from three US and four Canadian cancer centers. Cox proportional hazards regression, followed by bootstrap validation, was used to identify independent prognostic factors for OS. The median OS for the whole cohort was 22 months (95% CI, 20.2 to 26.5 months), and the median follow-up was 24.5 months. Overall, 396, 200, and 49 patients were treated with sunitinib, sorafenib, and bevacizumab, respectively. Four of the five adverse prognostic factors according to the Memorial Sloan-Kettering Cancer Center (MSKCC) were independent predictors of short survival: hemoglobin less than the lower limit of normal (P < .0001), corrected calcium greater than the upper limit of normal (ULN; P = .0006), Karnofsky performance status less than 80% (P < .0001), and time from diagnosis to treatment of less than 1 year (P = .01). In addition, neutrophils greater than the ULN (P < .0001) and platelets greater than the ULN (P = .01) were independent adverse prognostic factors. Patients were segregated into three risk categories: the favorable-risk group (no prognostic factors; n = 133), in which median OS (mOS) was not reached and 2-year OS (2y OS) was 75%; the intermediate-risk group (one or two prognostic factors; n = 301), in which mOS was 27 months and 2y OS was 53%; and the poor-risk group (three to six prognostic factors; n = 152), in which mOS was 8.8 months and 2y OS was 7% (log-rank P < .0001). The C-index was 0.73. This model validates components of the MSKCC model with the addition of platelet and neutrophil counts and can be incorporated into patient care and into clinical trials that use VEGF-targeted agents.

Despite years of research and hundreds of reports on tumour markers in oncology, the number of markers that have emerged as clinically useful is pitifully small. Often initially reported studies of a marker show great promise, but subsequent studies on the same or related markers yield inconsistent conclusions or stand in direct contradiction to the promising results. It is imperative that we attempt to understand the reasons that multiple studies of the same marker lead to differing conclusions. A variety of methodological problems have been cited to explain these discrepancies. Unfortunately, many tumour marker studies have not been reported in a rigorous fashion, and published articles often lack sufficient information to allow adequate assessment of the quality of the study or the generalisability of the study results. The development of guidelines for the reporting of tumour marker studies was a major recommendation of the US National Cancer Institute and the European Organisation for Research and Treatment of Cancer (NCI-EORTC) First International Meeting on Cancer Diagnostics in 2000. Similar to the successful CONSORT initiative for randomised trials and the STARD statement for diagnostic studies, we suggest guidelines to provide relevant information about the study design, preplanned hypotheses, patient and specimen characteristics, assay methods, and statistical analysis methods. In addition, the guidelines suggest helpful presentations of data and important elements to include in discussions. The goal of these guidelines is to encourage transparent and complete reporting so that the relevant information will be available to others to help them to judge the usefulness of the data and understand the context in which the conclusions apply.

The prognostic significance of morphologic parameters was evaluated in 103 patients with renal cell carcinoma diagnosed during 1961--1974. Pathologic material was classified as to pathologic stage, tumor size, cell arrangement, cell type and nuclear grade. Four nuclear grades (1--4) were defined in order of increasing nuclear size, irregularity and nucleolar prominence. Nuclear grade was more effective than each of the other parameters in predicting development of distant metastasis following nephrectomy. Among 45 patients who presented in Stage I, tumors classified as nuclear grade 1 did not metastasize for at least 5 years, whereas 50% of the higher grade tumors did so. Moreover, among Stage I tumors there was a significant difference in subsequent metastatic rate between nuclear grades 1 and 2. There was an apparent positive relationship between cell type and metastatic rate; clear cell tumors were less aggressive than predominantly granular cell tumors (metastatic rate 38% versus 71%). This relationship in part a function of the nuclear grade: only 5% of grade 3 and 4 tumors consisted of clear cells, whereas such high grades were seen in 57% of granular cell tumors. The size of the primary correlated well with the stage at the time of surgery. However, with the exception of extremely large and small tumors, the size was not useful in predicting the subsequent course of patients treated for Stage I tumors. Nuclear grade was the most significant prognostic criterion for the outcome of Stage I renal cell carcinoma.