title: CT response assessment combining reduction in both size and arterial phase density correlates with time to progression in metastatic renal cancer patients treated with targeted therapies.
abstract: BACKGROUND
  Response assessment is critical in evaluating effectiveness of anticancer treatment. Tyrosine kinase inhibitors (TKIs) in renal cell carcinoma (RCC) are associated with significant clinical benefit but may not result in significant tumor size reduction. Thus standard size-based response assessment with RECIST is insensitive, resulting in low response rates which do not reflect disease control measured by time to progression. We compared the use of combined size and density response criteria with standard size based criteria in metastatic RCC patients treated with TKI's.
  
  
  RESULTS
  Partial response (PR) and stable disease (SD) defined by modified criteria successfully identified patients with a long TTP (448 days) or short TTP (89 days) respectively (p = 0.002). Neither RECIST nor standard Choi criteria successfully discriminated between patients having a short or long clinical benefit.
  
  
  METHODS
  CT scans from 32 patients with metastatic RCC treated with either sunitinib (18) or cediranib (14) were assessed. Twelve patients were excluded from the analysis as ten had non-contrast enhanced scans due to renal impairment and two stopped treatment due to toxicity. Scans from 20 evaluable patients at baseline and 12 w on treatment were assessed using RECIST, Choi and modified criteria in which both a 10% decrease in size and 15% decrease in density were required to define a partial response (PR). Response assessment performed using each of the three methods was compared with time to disease progression (TTP) defined by RECIST using Kaplan-Meier statistics and Log-rank test with significance at 5%.
  
  
  CONCLUSIONS
  A combined reduction in both size and arterial phase density of RCC metastases treated with TKIs correlates with TTP. RECIST and standard Choi criteria appear inferior.
authors.affiliation: Mount Vernon Cancer Centre, Northwood, Middlesex, UK. nathan.pd@gmail.com
authors.forename: Paul D
authors.initials: PD
authors.lastname: Nathan
authors.forename: Anup
authors.initials: A
authors.lastname: Vinayan
authors.forename: David
authors.initials: D
authors.lastname: Stott
authors.forename: Jaspal
authors.initials: J
authors.lastname: Juttla
authors.forename: Vicky
authors.initials: V
authors.lastname: Goh
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D001158:Arteries / Q000473:pathology; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000473:pathology*; D018450:Disease Progression; D006801:Humans; D007211:Indoles / Q000627:therapeutic use; D007668:Kidney / Q000473:pathology; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000473:pathology*; D009362:Neoplasm Metastasis; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D011758:Pyrroles / Q000627:therapeutic use; D012189:Retrospective Studies; D000077210:Sunitinib; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden
chemical_list: D000970:Antineoplastic Agents; D007211:Indoles; D047428:Protein Kinase Inhibitors; D011758:Pyrroles; D000077210:Sunitinib