Does surgical approach influence margin status in partial nephrectomy for large tumors?

Surgical approach was not significantly linked to heightened risk of positive surgical margin (PSM) with respect to large, non-invasive renal masses, according to a US cohort study published in the Journal of Endourology. Increased tumor size from T1b to T2a was also not significantly linked to a higher risk of PSM.

“For renal masses < 4 cm, recent guidelines advocate that PN [partial nephrectomy] should be offered to all patients in whom an intervention is indicated and possess a tumor amenable to this approach,” wrote the authors, led by Abimbola Ayangbesan, MD, Weill Cornell Medicine, NY,NY. “Moreover, several studies have demonstrated the oncological and functional efficacy of PN in the surgical management of larger renal masses.”

Although the impact of PSMs on cancer outcomes is controversial, the surgeon’s goal in PN is to achieve cancer-free margins. Moreover, margin status is a quality-control indicator for PN. At the population-level, most research on the relationship between PSM and PN has focused on small kidney masses.

Dr. Ayangbesan and colleagues mined the National Cancer Database (NCDB)—which captures about 70% of newly diagnosed cancers—to find 7,495 adult patients who received PN for pathological T1b and T2a renal cell carcinoma (RCC) diagnosed between 2010 and 2013. They included conversions to open surgery in their analysis.

The researchers selected 2010 as a starting date because that is the first year that surgical approach was recorded in the NCDB. The team excluded patients with incomplete data on staging, surgical margin status, or surgical treatment modality.

The primary outcome of the study was surgical margin status. The investigators categorized PSM status as residual tumor NOS (not otherwise specified), microscopic residual tumor, or macroscopic residual tumor. The team defined the surgical approach as open, laparoscopic, robot-assisted, or conversion-to-open. As a secondary outcome, the investigators evaluated the influence of PSM on overall survival (OS).

In total, 504 of 7,495 (6.7%) PN patients had PSM. The team found that on multivariable analysis, neither laparoscopic/robot-assisted surgery (P=0.12) nor open surgery (P=0.44) were significantly associated with surgical margin.

Subsequent multivariable analysis took into account excluded pT3a patients staged at cT1b/cT2a based on a sensitivity analysis. In this cohort of 6,555 patients, laparoscopic/robot-assisted surgery, open surgery, tumor stage, and conversion-to-open surgery were not associated with PSM.

Finally, the investigators used a propensity score matched analysis to find that PSM did not predict OS (HR=0.95; 95% CI=0.47-1.92; P=0.88).

The investigators made note of important limitations of the current study. Specifically, due to its retrospective nature, no standardization of surgical modalities was possible. In addition, the researchers were unable to account for variables including individual surgeon volume, cancer-specific survival, recurrence-free survival, tumor complexity, and margin length.

“In a contemporary national cohort, surgical approach was not associated with increased risk of PSM for large, non-invasive renal masses,” the authors concluded. “Furthermore, increased size from T1b to T2a was also not associated with increased risk. These data suggest that surgical approach should be dictated by surgeon comfort level with an individual tumor, and not by size criteria alone.”

To read more about this study, click here.