Cancer trends tell tale of insufficient prevention
Australians are now developing cancer at slightly higher rates but dying of the disease less often, according to University of Sydney research published in the Medical Journal of Australia (MJA).
Professor Bruce Armstrong wrote the most notable trends in the latest Australian Institute of Health and Welfare (AIHW) statistics were annual five to six percent rises in the incidence of hepatic and prostatic cancers and four to five percent falls in mortality from Hodgkin lymphoma and cervical and testicular cancers.
"These examples reflect the annual trends in the rates of all cancers: increasing incidence of 0.7 percent and falling mortality of 1.4 percent," Professor Armstrong wrote.
Three factors drive trends in cancer incidence and mortality, he wrote.
"Changes in population exposure to cancer risk factors can increase or decrease cancer incidence and, after a delay, produce a parallel change in mortality. Liver cancer, which has shown an increasing annual incidence of 4.8 percent and increasing mortality of 3.0 percent, was an example of this."
Population screening that detects precancerous lesions can cause drops in both incidence and mortality.
"Cervical cancer shows this pattern, however, population screening that detects invasive cancer tends to increase incidence and decrease mortality," he said.
"The national prostate cancer screening program with PSA was an example of this pattern.
"Finally, in the absence of both incidence downtrend and any material effort at early diagnosis, treatment advances were the most likely contributor to mortality downtrend."
Professor Armstrong wrote that while Australia had done very well in preventing cancer deaths, the story was not so good in terms of primary prevention.
"Given that the data show 19 favourable and two adverse mortality trends, six favourable and 17 adverse incidence trends, this was an inescapable conclusion," Professor Armstrong wrote.
"This should come as no surprise: the AIHW estimated that in the 2004-05 financial year, Australia spent $3.19 billion on medical and hospital care and pharmaceuticals for cancer and $0.22 billion on community and public health programs—mostly for screening programs, not primary prevention. The imbalance is unlikely to be less now."