Prostate-specific antigen (PSA) screening and follow-up investigations in Māori and non-Māori men in New Zealand

Abstract

BackgroundMāori men in New Zealand have higher mortality from prostate cancer, despite having lower incidence rates. The objective of this study was to examine patterns of screening for prostate cancer in primary care and follow-up investigations after an elevated prostate-specific antigen (PSA) result in Māori and non-Māori men in order to help explain the observed differences in incidence and mortality.MethodsMen aged 40+ years were identified from 31 general practices across the Midland Cancer Network region. Computerised practice records were cross-referenced with laboratory data to determine the number and value of PSA tests undertaken between January 2007 and December 2010. Screening rates were calculated for the year 2010 by age, ethnicity, and practice. For men with an elevated PSA result information on specialist referrals and biopsy was extracted from practice records. Practice characteristics were assessed with respect to screening rates for Māori and non-Māori men.ResultsThe final study population included 34,960 men aged 40+ years; 14% were Māori. Māori men were less likely to be screened in 2010 compared with non-Māori men (Mantel Haenszel (M-H) age-adjusted risk ratio (RR), 0.52 [95% CI, 0.48, 0.56]). When screened, Māori men were more than twice as likely to have an elevated PSA result compared with non-Māori men (M-H age-adjusted RR, 2.16 [95% CI, 1.42, 3.31]). There were no significant differences between Māori and non-Māori men in the rate of follow-up investigations and cancer detection. Māori provider practices showed equal screening rates for Māori and non-Māori men, but they were also the practices with the lowest overall screening rates.ConclusionsMāori men were half as likely to be screened compared to non-Māori men. This probably explains the lower reported incidence of prostate cancer for Māori men. Practice characteristics had a major influence on screening rates. Large variation in screening behaviour among practices and differences in follow-up investigations for men with an elevated PSA result seems to reflect the uncertainty among GPs regarding PSA screening and management.

Differences in survival between Māori and New Zealand Europeans with prostate cancer

“…The proportion of Māori men diagnosed with metastatic disease was 19%, which is more in line with the three unscreened Nordic countries and in keeping with our previous findings (Obertová et al . ) that Māori men were half as likely to be offered screening than NZ European men. Overall 5‐year cancer‐specific survival (88.3%) in this cohort was better than the survival in the three Nordic countries (Brasso et al .…”

“…NZ general practitioners are half as likely to screen Māori men compared to non‐Māori men (Obertová et al . ) which may explain the lower proportion of localised cancer cases and a higher proportion of metastatic disease in Māori men: 19.1% of Māori men diagnosed with prostate cancer had metastatic disease at diagnosis compared to 9.8% for NZ Europeans. It is uncertain whether prostate cancer screening can save lives (Ilic et al .…”

“…We have also shown inequities between Māori men and NZ Europeans with prostate cancer in prostate cancer screening and referral (Obertová et al . ), and in the treatment of localised (Obertová et al . ) and metastatic cancer (Lawrenson et al .…”

“…Māori men were almost half as likely to be tested for prostate cancer as non‐Māori men and were twice more likely to be diagnosed with metastatic cancer than non‐Māori men (Obertová et al . ,b, ). The NZ national cancer registry has very incomplete data on staging and no information on treatment (Obertová et al .…”

The patient perspective on a first raised PSA test

“…While Māori make up 14% of men aged over 40 years in our region, Māori are half as likely to be tested. 24,27 Additionally, Māori have had a lower response rate than non-Māori to patient questionnaires. Our sample may have been biased by those who responded versus those who did not.…”