2007.11.07 – 131 cases of PV unsubstantiated
131 cases of PV unsubstantiated
To the Editor: In an Oct. 30 letter to the editor, Dante Picciano expressed concerns about the number of cases of the bone marrow cancer known as polycythemia vera (PV) in Schuylkill, Luzerne and Carbon counties. The Agency for Toxic Substances and Disease Registry would like to address Dr. Picciano’s concerns in the letter.
Published: Wednesday, November 7, 2007 3:00 AM EST
To the Editor:
In an Oct. 30 letter to the editor, Dante Picciano expressed concerns about the number of cases of the bone marrow cancer known as polycythemia vera (PV) in Schuylkill, Luzerne and Carbon counties. The Agency for Toxic Substances and Disease Registry would like to address Dr. Picciano’s concerns in the letter.
The Pennsylvania Cancer Registry contained 97 cases of PV from 2001-2005. The number of cases in the registry, and the calculated rates based on the tri-county population, suggested an excess of this cancer in the tri-county area. This finding is not new information. It was the basis for the request by the Pennsylvania Department of Health that ATSDR conduct an investigation to better describe these cases and whether they had any factors in common.
ATSDR did this in two ways. One was to determine in how many of the 97 registry cases the diagnosis of PV could be confirmed. The second was to find out if there were additional PV cases not reported to the registry. Specimens were collected from as many potential cases as possible to test for a recently identified genetic marker associated with PV called JAK-2. Information on these possible cases was also presented to a panel of experts on this disease to validate the diagnosis.
Among the 2001-2005 registry cases, only 38 of the 97 persons participated in the investigation. The remaining individuals either could not be found, were deceased or chose not to take part. Of the persons who did take part, the diagnosis of PV was confirmed in only 18; four additional cases were considered probable. An additional 34 persons were identified outside of the registry, but the diagnosis dates for these cases ranged from 1990 to 2007 (an 18-year time period) rather than the five-year period available in the cancer registry. Additionally, some of these cases did not reside in the tri-county area at the time of diagnosis. Of these additional 34 persons, only 20 could be confirmed as having PV. These numbers are the basis for the 38 confirmed cases of PV reported by ATSDR.
As was said repeatedly during the public meeting held on Oct. 24, the information presented pertained only to those individuals who participated in the investigation. That is because we are unable to determine how many of the individuals from the registry who were lost to follow-up actually have PV. It is likely that some proportion of these persons have this disease. But we also know from the results among those who did take part in the investigation that some of those lost to follow-up very likely do not have PV.
For these reasons, the number of 131 cases mentioned by Dr. Picciano in his letter cannot be substantiated. Regardless of what the actual number is, the conclusions conveyed to the public on Oct. 24 are unchanged. There is more PV in Luzerne and Schuylkill counties than would be predicted based on estimated national rates.
We believe this deserves further study and are committed to continuing our work on this problem in the tri-county area.
Dr. Steve Dearwent
Health Investigations Branch
Division of Health Studies Agency for Toxic Substances and Disease Registry