The expert panel set up to investigate cancer cluster concerns at Helensburgh has released details of its investigation as reports surfaced of a seventh case of blood cancer in the community.
The panel, formed to look into childhood leukaemia and lymphoma, found that a higher rate of leukaemia between 2005 and 2008 most likely arose "by chance". Rates of lymphoma were within the normal range.
Yesterday Illawarra Public Health Unit acting director Curtis Gregory said "while an additional case is never easy for those it affects, it would not be unexpected, simply because these types of cancers do occur".
"The investigation looked at the period before 2005 and after 2008 and is aware of some additional cases in these periods but not at elevated incidence levels," Mr Gregory said. "It also examined non-childhood cancers and found no unusual activity in these ages."
Diane Young, mother of Matthew, 9, who became the sixth Helensburgh child in five years to be diagnosed with blood cancer, has written to NSW Health Minister Jillian Skinner with her concerns of the unconfirmed seventh case.
She said she had recently discovered there was "another Burkitts Lymphoma child".
Mr Gregory said the "rate of disease occurrence in the community was the issue".
"Individual cases are difficult for those involved, however, they may form part of the natural rate of disease in a community," he said.
"The findings of the panel acknowledged this through identifying that the increased incidence of childhood leukaemia did not persist beyond 2008. While there have been additional cases, the higher incidence rate did not continue and fell back down to much lower levels," he said. "The expectation that this would mean there would never be another case of either leukaemia or non-Hodgkin's lymphoma is unrealistic, as these diseases occur naturally within populations."
In her letter to the minister, Mrs Young again called for water, air and soil testing.
But the panel, in its report published on the Illawarra Shoalhaven Local Health District website yesterday, said neither leukaemia nor non-Hodgkin's lymphoma had a level of soil or water pollution associated with the cause.
Mr Gregory, a panel advisor, said the two cancers "occur naturally within populations and there is no way to eliminate them from occurring".
The two blood cancers were considered as separate illnesses because of the way they occurred and developed.
"What is common to both diseases is that neither have had a level of soil or water pollution that is associated with their cause," Mr Gregory said. "There are no proven causes of either childhood leukaemia or non-Hodgkin's lymphoma outside of those agents used to treat the disease such as ionising radiation or some cytotoxic drugs.
"The lack of a proven causal environmental agent means that the incidence of these cancers cannot be used as an indicator for environmental risks simply because there is no link.
"This has been examined internationally and aside from occupational benzene exposure for adults, no risk has been found," he said.
"The distribution of diseases is not even and can clump in multiple cases at locations and, where the disease is uncommon, any increase can stand out, which is why we investigate."
Mr Gregory said the main points to be taken from the findings were that the "increased rate fell after 2008, showing a drop off in case numbers and that there was no associated increased risk in Helensburgh."