Does Tumor Size or Microvascular Invasion Affect Prognosis in Patients with Renal Cell Carcinoma?

Prognostic value of the Leibovich prognosis score supplemented by vascular invasion for clear cell renal cell carcinoma

PURPOSE

We assessed whether supplementing the Leibovich prognosis score with vascular invasion would improve prognostic value to predict metastatic disease in patients with nonmetastatic clear cell renal cell carcinoma.

MATERIALS AND METHODS

We retrospectively evaluated the pathology records of 1,754 patients with nonmetastatic clear cell renal cell carcinoma treated with surgery between 1984 and 2006 at a single tertiary academic center. The Leibovich prognosis score was supplemented by additional scoring for vascular invasion. Metastasis-free survival was assessed using the Kaplan-Meier method for each score category. A Cox regression model was used for multivariate testing. Predictive accuracy was determined by the Harrell concordance index and decision curve analysis.

RESULTS

Median followup was 84 months. Ten-year metastasis-free survival probability for a score of 0 to 1 and 2 to 8 or greater was 95%, 83%, 78%, 81%, 69%, 51%, 15% and 13%, respectively. The concordance index was 0.792 compared to 0.778 from our external validation of the Leibovich prognosis score using routine pathological findings (p <0.05). Decision curve analysis also favored the predictive ability of the novel model.

CONCLUSIONS

Adding vascular invasion improved the predictive accuracy of our validation data by 1.4% over that of the Leibovich prognosis score. Patients with a score of 7 or greater had a more than 85% probability of metastatic disease at 10 years. Thus, they could be considered candidates for adjuvant treatment trials.

Histological characterisation of small renal masses and incidence of silent renal masses

With the introduction of sonographic and CT examinations, the number of small renal masses detected has increased. Benign neoplastic lesions are usually smaller than 4 cm in size, whilst the most common types of renal cell carcinomas have a mean size greater than that, but we must not forget that a significant number of small masses are renal cell carcinomas; even though the rate of benign cases increases as the diameter of the lesions decreases, therefore, size itself cannot be used to rule out a diagnostic of malignancy and often image characteristics are not enough to predict the nature of the lesion with certainty. In this case, histological confirmation must be recommended. Ideally, the histological study must be conducted on the surgical specimen, even though biopsy can be an option in selected cases.