#SUO14 - Session Highlights: Accelerated growth rate of multifocal tumors after initial radiofrequency ablation

BETHESDA, MD USA (UroToday.com) - Radiofrequency ablation (RFA) is a minimally-invasive, nephron-sparing treatment for patients with localized small renal cell carcinoma. Dr. Mario Taylor and colleagues from National Institutes of Health (NIH) report on a subset of patients with multifocal renal cell carcinoma treated with RFA who subsequently demonstrated accelerated growth rates in non-treated renal tumors after RFA.

suoA database of patients with multifocal RCC enrolled in a prospective phase II trial of RFA between 1999 to 2004 was retrospectively reviewed. Patients who underwent ipsilateral secondary intervention following RFA were recorded, and patients with accelerated growth rate of subsequent renal tumors were identified. Accelerated growth rate is defined as growth > 0.5 cm/year. Patients with incomplete ablation were excluded from the study. Other clinical parameters measured were proximity of the new lesion to initial RFA site, timing of onset of accelerated growth, and contrast enhancement. Growth rates prior to initial RFA were recorded when available.

Sixty-three patients were enrolled and 113 lesions were treated with RFA. Eighteen tumors in 15 patients (24%) demonstrated accelerated growth rate following RFA. Average growth rate after RFA was 1.10 cm/year. Ten of 18 tumors with growth were visible on pre-RFA radiographic imaging. For these lesions, the average pre-RFA growth rate was 0.26 cm/year and the average post-RFA growth rate increased to 1.31 cm/year. The mean size of the tumors was 3.24 cm.

They conclude that 24% of the patients with multifocal RCC demonstrated accelerated growth rate after RFA. The majority of the tumors were not in proximity to initial RFA lesion. The mechanism of this is unclear and subsequent research is needed to validate these observations. The data show that RFA, while benefiting patients with small multi-focal tumors, can also potentially promote growth of other tumors and needs to be performed with caution.

Presented by:
Mario Taylor,1 Jason Rothwax,1 W. Marston Linehan,1 Brad Wood,2 and Adam Metwalli1
1Urologic Oncology Branch, National Cancer Institute National Institutes of Health, Bethesda, MD, USA; 2Center for Interventional Oncology, National Cancer Institute National Institutes of Health, Bethesda, MD, USA

Reported by:
Mohammed Haseebuddin, MD*
from the 2014 Winter Meeting of the Society of Urologic Oncology (SUO) "Defining Excellence in Urologic Oncology" - December 3 - 5, 2014 - Bethesda, MD USA

*Fox Chase Cancer Center, Philadelphia, PA USA