Impact of Perioperative Infection on Cancer Specific Survival after Nephrectomy for Renal Cell Carcinoma

Purpose: Several case reports have documented rare spontaneous cancer regression following systemic infections. Immune related targeted therapies are now available for many cancers, including renal cell carcinoma. We hypothesized that perioperative infection after nephrectomy for renal cell carcinoma may impact long-term cancer specific survival. Materials and Methods: We performed a retrospective cohort study using SEER (Surveillance, Epidemiology and End Results)-Medicare claims data from 2004 to 2011. ICD-9 and CPT codes were used to identify patients older than 65 years who underwent radical or partial nephrectomy for renal cell carcinoma. Patients hospitalized for infection within 30 days of surgery were identified. Study exclusion criteria included death within 90 days of surgery, immunodeficiency and metastatic disease at diagnosis. Kaplan-Meier curves were used to evaluate cancer specific survival between infection vs no infection groups. A Cox proportional hazards model was created to assess survival while controlling for age, gender, race, Elixhauser index, tumor grade, tumor size, histological subtype, AJCC (American Joint Committee on Cancer) stage, systemic therapy and geographic region. Results: Of 8,967 patients 493 (5.5%) were hospitalized for infection after nephrectomy. Median age was 74 years (IQR 69-79), the mean +/- SD Elixhauser index was 4.9 +/- 7.4 and median followup was 42 months (IQR 22-67). Following nephrectomy univariable Cox regression showed a nonsignificant improvement in cancer specific survival in patients with a serious infection requiring hospitalization (HR 0.84, 95% CI 0.69-1.00, p = 0.054). Cox multivariable regression revealed significant improvement in cancer specific survival for the same population (HR 0.75, 95% CI 0.57-0.99, p = 0.04). This effect was primarily due to patients with larger (7 cm or greater) tumors (HR 0.67, 95% CI 0.44-0.99, p = 0.049). No impact was observed among patients with smaller (less than 7 cm) tumors (HR 0.82, 95% CI 0.57-1.19, p = 0.3). Conclusions: In patients with T2 (7 cm or greater) renal cell carcinoma who undergo nephrectomy perioperative infection may improve cancer specific survival.