Demographic Differences in Stage at Diagnosis and Cervical Cancer Survival in New Zealand, 1994–2005

Abstract

To investigate ethnic, socioeconomic, and urban/rural differences in stage at diagnosis and cervical cancer survival in New Zealand. The study involved 1594 cervical cancer cases registered during 1994-2005. Cox regression was used to estimate adjusted cervical cancer mortality hazard ratios (HRs). Māori and Pacific women had higher death rates than Other (predominantly European) women, with age and year of diagnosis adjusted HRs of 2.15 (95% CI 1.68-2.75) and 1.98 (95% CI 1.25-3.13), respectively, whereas Asian women had a lower (nonstatistically significant) risk (0.81, 95% CI 0.47-1.42). Adjustment for stage reduced the HR in Māori to 1.62 (95% CI 1.25-2.09), but there was little change for Pacific or Asian women. These patterns varied over time: for cases diagnosed during 1994-1997, the HR for Māori women was 2.34 (95% CI 1.68-3.27), which reduced to 1.83 (95% CI 1.29-2.60) when adjusted for stage; for cases diagnosed during 2002-2005, the corresponding estimates were 1.54 (95% CI 0.75-3.13) and 0.90 (95% CI 0.43-1.89). Socioeconomic status and urban/rural residence had only marginal effects. There were major ethnic differences in cervical cancer survival in New Zealand that were only partly explained by stage at diagnosis. These patterns varied over time, with postdiagnostic factors playing an important role in the high Māori mortality rates in the 1990s, but in more recent years, the excess mortality in Māori women appeared to be almost entirely due to stage at diagnosis, indicating that ethnic differences in access to and uptake of screening and treatment of premalignant lesions may have been playing a major role.