Prevalence and outcomes of peritumor fat involvement following partial nephrectomy for radiologic T1 renal cancer

Context: Partial nephrectomy is becoming the standard of care in management of small renal tumors and excision of the peritumor fat is recommended for accurate staging. During the surgery, the overlying fat may be excised for accurate visualization of margins or maybe inadvertently left behind when performing a partial nephrectomy in an obese patient. We investigated the prevalence of fat involvement in these patients. Aims: The aim was to document the prevalence of peritumor fat involvement discovered after partial nephrectomy performed for radiologic T1 renal cancer. Settings and Design: Between 2005 and 2011, 107 partial nephrectomy procedures were performed for radiologic T1 disease. Statistical Analysis: All analyses were performed using SAS 9.2. Subjects and Methods: Patients were classified as: Group A (n = 88 patients), patients with stage T1a (tumor size ≤4 cm) and Group B (n = 24 patients) patients with stage T1b (tumor size 4-7 cm). Results: The overall prevalence of peritumor fat involvement was 1.86% (n = 2). The two patients had tumor ≤4 cm in size of the papillary subtype and were followed for 61 and 57 months, respectively. Both were living and without recurrence. Patient demographics and tumor characteristics did not differ between the two groups except, Fuhrman Grades 3 and 4 were statistically more prevalent in Group B (<0.01). Tumor grade, clear cell type cancer and stage T1b did not correlate with peritumor fat involvement in the study population. Conclusions: Our study revealed a low prevalence of peritumor fat involvement in radiologic pT1 renal cancer; however, peritumor fat removal is still recommended.