title: Perineal application of cosmetic talc and risk of invasive epithelial ovarian cancer: a meta-analysis of 11,933 subjects from sixteen observational studies.
abstract: OBJECTIVE
  Prior epidemiological studies suggest an association between perineal cosmetic talc use and increased risk of epithelial ovarian cancer. A meta-analysis was performed to evaluate this suspected association.
  
  
  METHODS
  Using previously described methods, a protocol was developed for a meta-analysis examining the association between perineal talc use versus non-use and the development of invasive epithelial ovarian cancer. Literature search techniques, study inclusion criteria and statistical procedures were prospectively defined. Data from observational studies were pooled using a general variance based meta-analytic method employing confidence intervals previously described by Greenland. The outcome of interest was a summary relative risk (RRs) reflecting the risk of ovarian cancer development associated with perineal talc use versus non-use. Sensitivity analyses were performed when necessary to explain any observed statistical heterogeneity.
  
  
  RESULTS
  Sixteen observational studies meeting protocol specified inclusion criteria were located via a comprehensive literature search. These studies enrolled a total of 11,933 subjects. Analysis for heterogeneity demonstrated that the data were homogenous (p = 0.17) and could be combined in a meta-analysis. Pooling all sixteen studies yielded a RRs of 1.33 (CI = 1.16-1.45), a statistically significant result suggesting a 33% increased risk of ovarian cancer with perineal talc use. Despite this finding, the data showed a lack of a clear dose-response relationship making the RRs of questionable validity. Further sensitivity analyses showed that hospital-based studies showed no relationship between talc use and ovarian cancer risk, i.e. RRs 1.19 (0.99-1.41) versus population-based studies (RRs = 1.38, CI = 1.25-1.52). This suggests that selection bias and/or uncontrolled confouding may result in a spurious positive association between talc use and ovarian cancer risk in population-based studies.
  
  
  CONCLUSIONS
  The available observational data do not support the existence of a causal relationship between perineal talc exposure and an increased risk of epithelial ovarian cancer. Selection bias and uncontrolled confouding may account for the positive associations seen in prior epidemiological studies.
authors.affiliation: Department of Clinical Oncology, Marshfield Clinic Cancer Center, Marshfield, WI, USA. Metaresearch@hotmail.com
authors.forename: Michael
authors.initials: M
authors.lastname: Huncharek
authors.forename: J F
authors.initials: JF
authors.lastname: Geschwind
authors.forename: Bruce
authors.initials: B
authors.lastname: Kupelnick
mesh_terms: D005260:Female; D006801:Humans; D019370:Observation; D010051:Ovarian Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D010502:Perineum; D013627:Talc / Q000009:adverse effects*
chemical_list: D013627:Talc