title: Meta-analysis of regression of advanced solid tumors in patients receiving placebo or no anti-cancer therapy in prospective trials.
abstract: BACKGROUND
  A meta-analysis of prospective trials systematically investigated regression of advanced solid tumors in patients receiving placebo or no anticancer therapy to inform on spontaneous regressions.
  
  
  METHODS
  Arms of randomized controlled trials (RCTs) of metastatic solid tumors receiving placebo or no anti-cancer therapy were used. Statistical analyses were conducted to calculate the overall response rate (ORR) and to detect differentials based on histology, progression at baseline and prior therapies.
  
  
  RESULTS
  A total of 7676 patients were evaluable from 61 RCTs evaluating 18 solid tumors. The ORR was 1.95% (95% CI: 1.52-2.48%). There was no significant effect of histology (p=0.110), baseline progressive disease (p>0.20) or the line of therapy (p>0.20) on ORR.
  
  
  CONCLUSIONS
  Spontaneous regressions are seen across all advanced solid tumors. Some malignancies demonstrated higher rates of spontaneous regressions and may be relatively immunotherapy responsive.
authors.affiliation: Department of Internal Medicine, University of Alabama at Birmingham (UAB), AL, United States.
authors.forename: Pooja
authors.initials: P
authors.lastname: Ghatalia
authors.affiliation: Department of Biostatistics, UAB School of Medicine, United States.
authors.forename: Charity J
authors.initials: CJ
authors.lastname: Morgan
authors.affiliation: Department of Internal Medicine, Section of Medical Oncology, UAB Medical Center, United States. Electronic address: gsonpavde@uabmc.edu.
authors.forename: Guru
authors.initials: G
authors.lastname: Sonpavde
mesh_terms: D002986:Clinical Trials as Topic; D018450:Disease Progression; D006801:Humans; D009369:Neoplasms / Q000473:pathology* / Q000628:therapy*; D010919:Placebos; D012074:Remission Induction; D047368:Tumor Burden
chemical_list: D010919:Placebos
keywords: Immune therapy; Meta-analysis; Placebo; Spontaneous regression