title: Factors affecting survival in 37 consecutive patients undergoing de novo stereotactic radiosurgery for contiguous sites of vertebral body metastasis from renal cell carcinoma.
abstract: OBJECTIVE
  Palliative resection of renal cell carcinoma (RCC) spinal metastasis is indicated in cases of neurological compromise or mechanical instability, whereas conventional external beam radiotherapy (EBRT) is commonly used for pain control. Recently, spinal stereotactic radiosurgery (SRS) has emerged as a safe alternative, delivering higher therapeutic doses of radiation to spinal metastases. To better understand factors affecting survival in patients undergoing spinal SRS for metastatic RCC, the authors performed a retrospective analysis of a consecutive series of cases at a tertiary cancer center.
  
  
  METHODS
  Patients harboring contiguous sites of vertebral body involvement from metastatic RCC who received upfront spinal SRS treatment at The University of Texas MD Anderson Cancer Center between 2005 and 2012 were identified. Demographic data, pain scores, radiographic data, overall survival, complications, status of systemic disease, neurological and functional status, and time between primary diagnosis and diagnosis of metastasis (systemic and spinal) were analyzed to determine their influence on survival.
  
  
  RESULTS
  Thirty-seven patients receiving treatment for 40 distinct, contiguous sites of disease were included. The median overall survival after spinal SRS was 16.3 months (range 7.4-25.3 months). Univariate analysis revealed several factors significantly associated with improved overall survival. Local progression after spinal SRS was associated with worse overall survival compared with sustained local control (HR 3.4, 95% CI 1.6-7.4, p = 0.002). Median survival in patients with a Karnofsky Performance Scale (KPS) score ≥ 70 was longer than in patients with a KPS score < 70 (HR 4.7, 95% CI 2.1-10.7, p < 0.001). Patients with neurological deficits at the time of spinal SRS had a shorter median survival than those without (HR 4.2, 95% CI 1.4-12.0, p = 0.008). Individuals with nonprogressive systemic disease at the time of spinal SRS had a longer median survival than those with systemic progression at the time of treatment (HR 8.3, 95% CI 3.3-20.7, p < 0.001). Median survival in patients experiencing any metastasis < 12 months after primary RCC diagnosis was shorter than in patients experiencing any metastasis > 12 months after primary diagnosis, a difference that approached but did not attain significance (HR 1.9, 95% CI 0.90-4.1, p = 0.09). On multivariate analysis, local progression of disease after spinal SRS, metastasis < 12 months after primary, KPS score ≤ 70, and progression of systemic disease at time of spinal SRS all remained significant factors influencing survival (respectively, HR 3.7, p = 0.002; HR 2.6, p = 0.026; HR 4.0, p = 0.002; and HR 13.2, p < 0.001).
  
  
  CONCLUSIONS
  We identified several factors associated with survival after spinal SRS for RCC metastases, including local progression, time between first metastasis and primary RCC diagnosis, KPS score, presence of neurological deficits, and progressive metastatic disease. These factors should be taken into consideration when considering a patient for spinal SRS for RCC metastases.
authors.affiliation: Departments of Neurosurgery and Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Sellin
authors.forename: William
authors.initials: W
authors.lastname: Reichardt
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Bishop
authors.forename: Dima
authors.initials: D
authors.lastname: Suki
authors.forename: Laurence D
authors.initials: LD
authors.lastname: Rhines
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Settle
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Ganesh
authors.initials: G
authors.lastname: Rao
authors.forename: Eric L
authors.initials: EL
authors.lastname: Chang
authors.forename: Claudio E
authors.initials: CE
authors.lastname: Tatsui
mesh_terms: D000328:Adult; D000368:Aged; D002173:Cancer Care Facilities; D002292:Carcinoma, Renal Cell / Q000401:mortality* / Q000556:secondary; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017567:Karnofsky Performance Status; D007680:Kidney Neoplasms / Q000401:mortality* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010149:Postoperative Pain / Q000401:mortality; D010166:Palliative Care / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models; D011829:Radiation Dosage; D016634:Radiosurgery / Q000009:adverse effects / Q000401:mortality*; D012307:Risk Factors; D013125:Spinal Neoplasms / Q000401:mortality* / Q000556:secondary
keywords: CTV = clinical target volume; EBRT = external beam radiotherapy; ESCC = epidural spinal cord compression; GTV = gross tumor volume; IMRT = intensity-modulated radiation therapy; KPS = Karnofsky Performance Scale; RCC = renal cell carcinoma; SINS = spinal instability neoplastic score; SRS = stereotactic radiosurgery; VAS = visual analog scale; oncology; renal cell carcinoma; spinal metastasis; stereotactic radiosurgery