Smoking-related Cancers in Maori and non-Maori in New Zealand, 1974-1993: Fewer Bladder Cancers among Maori.

Smoking is, and long has been, more prevalent among Maori than non-Maori in New Zealand. Lung cancer, but not other smoking-related cancers, is known to be markedly more common among Maori than non-Maori. Incidence and mortality data from the New Zealand Cancer Registry for cancers of the mouth/pharynx, oesophagus, pancreas, larynx, kidney and bladder, as well as lung/pleura, during the period 1974 to 1993 were analysed by sex to determine whether the rates of each of these smoking-related cancers were higher in Maori than in non-Maori. Truncated (35-64 yr) age-standardized incidence rates for 1974-93 were significantly higher in Maori than non-Maori for cancers of the pancreas, lung/pleura and kidney (both sexes), mouth/pharynx and oesophagus (males only). There was no difference between the Maori and non-Maori rates for cancer of the larynx, and bladder cancer incidence was significantly lower in Maori than non-Maori. Mortality rates followed a similar pattern as those for incidence for cancers of the pancreas, larynx, lung/pleura and kidney (both sexes) and bladder (males only). The pattern predicted by the higher prevalence of smoking in Maori than non-Maori was borne out for all smoking-related cancers except bladder and laryngeal cancer. Under-enumeration through lower access to health services may have contributed to the lower than expected rates of bladder cancer in Maori, but a role for a genetically or lifestyle related protective effect is suggested.