Positive surgical margins (PSM) are associated with worse overall survival following partial nephrectomy (PN), a new study suggests.

Using the National Cancer Data Base (NCDB), investigators led by Robert Abouassaly, MD, MS, of University Hospitals Case Medical Center in Cleveland, studied 6,038 cases of pathologic T1–T3a of non-metastatic renal cell carcinoma (RCC) who underwent PN during 2003–2006. Of these patients, 302 (5.3%) had PSM. The median follow-up was 71 months. At last contact, 699 patients (11.6%) died—51 (17.2%) PSM patients and 647 (11.3%) of the 5,736 patients with negative surgical margins (NSM), the investigators reported online ahead of print in the Journal of Endourology.

Higher pathologic T stage and higher comorbidity score were the only factors significantly associated with PSM, according to the researchers.

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The unadjusted 5-year overall survival (OS) for the cohort was 92%. PSM was significantly associated with decreased 5-year OS compared with NSM (89% vs. 92%). On multivariable analysis, PSM was associated with a significant 34% increased risk of all-cause mortality, Dr. Abouassaly and colleagues concluded.

The authors cautioned that the association between PSM and worse OS does not imply causation. “Since the NCDB does not include information on cancer recurrence, cause of death, or secondary treatments, the exact cause of the excess mortality rate in PSM patients is unknown and not necessarily due to RCC,” they wrote.

Still, the authors stated that their study is the first to detect a significant difference in OS patients with PSM, which may be attributed to the inclusion of a large cohort, “ample prevalence of PSM,” a “statistically sufficient event rate,” longer term follow-up data, and other variables.

Limitations of the study include susceptibility to bias because of its retrospective design and the limitations of the NCDB. “Since follow-up information in the NCDB is limited to vital status, we were only able to assess OS as our primary outcome.”