Source: DGNews  |  Posted 2 years ago

By Deborah Brauser

ORLANDO, Fla -- March 2, 2009 -- Partial nephrectomy (PN) offers a safe and viable alternative to radical nephrectomy (RN) in the majority of patients with clinical T1b renal tumors, while elective PN is associated with a significantly better overall survival, according to a large cohort study.

The research findings were presented here at the American Society of Clinical Oncology 2009 Genitourinary Cancers Symposium (ASCO-GU). The event was cosponsored by the American Society for Therapeutic Radiology and Oncology and the Society of Urologic Oncology.

Lead investigator Christopher Weight, MD, Urology Resident, Cleveland Clinic, Cleveland, OH, discussed the results of this study in a poster session on February 28.

Dr. Weight and colleagues evaluated 1,004 patients with renal masses between 4 and 7 cm who underwent extirpative surgery at the Cleveland Clinic from 1998 to 2006.

The investigators calculated the propensity to undergo PN versus RN using a multivariate logistic regression model and preoperative patient characteristics. This propensity score was then used in multivariate models to identify significant predictors of overall survival and cancer-specific survival.

Patient characteristics included in the analysis were age, tumor size, epidermal growth factor receptor concentration, presence of contralateral disease, solitary kidney status, extra-renal extension, and Charlson comorbidity index.

The 524 patients in the PN group had a mean age of 63 years and 69% were male, while the 480 patients in the RN group had a mean age of 65 years and 61% were male.

As part of a predetermined subset analysis, 212 PN patients and 298 RN patients who had no imperative indication for PN (ie, sporadic, unilateral renal masses, a growth factor receptor >60, and a normal contralateral kidney) were included in an elective cohort.

At the end of the study, median follow-up for the entire cohort was 48 months. Selection of RN versus PN was not random, with those undergoing RN more likely to be older, have larger tumors, higher pathologic stage, and higher burden of comorbid diseases; whereas those getting a PN were more likely to have a solitary kidney, presence of contralateral disease, and decreased epidermal growth factor receptor concentrations.

When they controlled for known predictors of survival, the researchers found that there was no difference in overall survival between study groups. However, patients undergoing PN experienced as good or better cancer-specific survival at every stage and grade than those treated with RN.

In the elective cohort, the PN-treated group continued to have better overall survival (hazard ratio = 0.37; 95% confidence interval, 0.15-0.96) when the researchers controlled for both propensity to undergo PN and pathologic stage.

Said Dr. Weight, "In this study, the results showed that partial nephrectomy was associated with a better overall survival even on multivariate analysis controlling for age, comorbidities, pathologic stage, and other known predictors of overall survival. This improvement seems to be due in part to better preservation of renal function during partial nephrectomy."

"This was a big cohort," continued Dr. Weight. "Previous cohorts have only had about 300 partials whereas in this one we had 520 partials versus 480 radicals. It suggests that when it's technically feasible, you're probably going to have better overall survival if you can treat a patient with a partial nephrectomy."

[Presentation title: A Nonrandomized Comparison of Overall Survival in Patients With Clinical T1b Renal Tumors Treated With Radical Nephrectomy (RN) or Partial Nephrectomy (PN). Abstract 336]