Abstract
We are writing to state that the American Cancer Society does not endorse the published study entitled “Fine Particulate Matter and Total Mortality in Cancer Prevention Study Cohort Reanalysis” 1 for several reasons. First, the Methods section of this article indicates that the Cancer Prevention Study-II (CPS-II) data “were obtained from a source with appropriate access to these data, as explained in the Acknowledgements (Page 2).” 1 The acknowledgments at the end of the article then thank the American Cancer Society “for making it possible for me to obtain unique access to the CPS II cohort data and detailed documentation (Page 10).” 1 It is important to clarify that the American Cancer Society did not provide CPS-II data or documentation to James Enstrom, the author of the study. In fact, we have no knowledge of how nor from what source he obtained the data used in the analysis, and therefore, we cannot confirm the data are from the CPS-II cohort.
Elsewhere in the article, the author notes that the American Cancer Society, “had refused to work with him…regarding collaborative analysis of the CPS II data,” and reasons for the refusal were described in reference 14. 1 Briefly, we post our CPS Data Access Policies and Procedures on our website to facilitate access to qualified external scientists whose proposals for hypothesis-based research meet the Society’s criteria for collaboration and further our public health mission. The consideration of potential collaborators is appropriate and necessary for the Society to determine who should be permitted to utilize our data and for what purpose. If there is a failure on the applicant’s part to provide requested information, then access to the data is denied. As noted in reference 14, the author of the article had twice failed to provide information regarding his employment at that time. He also failed to provide the funding sources for his prior research and the research proposed, as well as the identity of any other collaborating researchers on the proposed CPS-II analysis. Moreover, the author writes that “the Division number and Unit number assigned by ACS to each CPS II participant have been used to define their county of residence (Page 2).” 1 For clarification, these numbers represent the American Cancer Society Division and Unit affiliation of the volunteer who recruited the participant, not the individual CPS-II participant. In fact, volunteers sometimes recruited participants from different states (eg, volunteer lived in California whereas participant lived in Ohio). Thus, when classified using the Division and Unit numbers, the geographically defined exposure measure will be highly inaccurate for some participants. Finally, the Funding section indicates that “the American Cancer Society provided the funding for the establishment of the CPS II cohort in 1982, the mortality follow-up from 1982 through 1988, and the preparation of the computerized files and documentation for this research (Page 10).” 1 As noted above, we have no knowledge of how nor from what source the author obtained the data, and therefore, we cannot substantiate the claim that we provided funding for the preparation of the computerized files and documentation for this research.