Cancer registration in victoria, Australia, 1982–1987

Comparing incidence of and mortality from cancer within a given population yields several benefits. One of these is the opportunity, when trends in incidence differ from those in mortality, to derive inferences about the potential role of improved diagnosis in the rise of incidence rates, and about therapeutic advancements in reducing mortality.

Trends in incidence of and mortality from various cancers or groups of cancers (comprising 55,682 new malignant tumours and 26,528 certified cancer deaths) over the period 1974–1993 were compared using, respectively, data from the Cancer Registry of the Swiss Canton of Vaud (with about 600,000 inhabitants) and those provided by the Swiss Federal Statistical Office.

The overall cancer incidence increased by 10% to 30% in both sexes and various age groups, whereas mortality remained approximately the same. The sites primarily responsible for these divergent trends were breast, prostate and colorectal, three sites where cancers have been less frequently diagnosed since the advent of certain technical advancements and the introduction of screening. Other contributors to the divergent trends were testicular cancer, Hodgkin's disease and leukaemias, i.e., the sites for which the most substantial therapeutic advancements have been achieved.

These data are fairly reassuring, since they are inconsistent with an ongoing cancer epidemic in this European population. However, they are also incompatible with the presence of major advancements in the prevention and treatment of cancer.

The incidence of cancers of the colon, breast and prostate in Australian and Italian born residents of Victoria, Australia were compared with the incidence of these cancers in Italy. Italian migrants' rates were between those of the Australian born and those from Italian cancer registries. Italian migrants' rates for colon cancer (males 23.1 and females 15.8 per 100 000) differed from rates in Ragusa (males 12.1 and females 10.4 per 100 000) but not from rates in Parma or Varese. The migrants' breast cancer rate was similar to the rate in Ragusans (48.7 vs 46.7) and their prostate cancer rate of 27.3 was higher than all Italian registries. Modelling identified that Italian migrants' rates by age were intermediate to Australian and Italian rates, but indistinguishable from cancer rates in Ragusa, except for colon cancer which demonstrated an interaction with age.