Age has been the main
Age has been the main demographic factor used for targeting Australian screening programs . The National Breast Screening Program actively invites women aged from 50 to 74 years for biennial screening. The National Cervical Screening Program has been using HPV (human papillomavirus) testing since December 2017 and recommends 5-yearly screening of women aged 25–74 years. The National Bowel Cancer Screening Program invites people to bowel screening between ages 50 and 74 years.
Little account has been taken of other socio-demographic factors, such as ethnicity, when targeting screening programs, although they LY3009120 can affect cancer risk . Aboriginal and Torres Strait Islander peoples (referred to in this paper as Aboriginal people) are generally diagnosed with cancer at a younger age than non-Aboriginal people . It is unclear whether national screening programs should be modified for Aboriginal people to optimize screening coverage and outcomes.
Material and methods Cases were categorised as Aboriginal or non-Aboriginal people. In 2011, about 30% of Australian Aboriginal people lived in NSW . Due to known under-recording of Aboriginal people, we used a ‘weight of evidence’ method to enhance the recording of Aboriginal status using data from the NSW Admitted Patient Data Collection, the NSW Emergency Department Data Collection and the Australian Coordinating Register Cause of Death Unit Record File . Approval for the study was obtained from the NSW Population and Health Services Research Ethics Committee (HREC/15/CIPHS/15) and the Aboriginal Health and Medical Research ethics committee (HREC Ref. No. 1201/16). The study operated under guidance from the Aboriginal Advisory Group of the Cancer Institute NSW.
Results Aboriginal people were on average younger than non-Aboriginal people at diagnosis and age distributions differed significantly by Aboriginal status for all cancers (all p-values<0.01) (Table 1). IRRs indicated that Aboriginal women had lower or similar age-specific breast cancer incidence rates than non-Aboriginal people in women aged <60 years and higher age-specific cancer incidence in older age groups (≥60 years) (Table 2, Fig. 1). There was a significant difference in cancer incidence by Aboriginal status by age (p < 0.001). For cervical cancer, Aboriginal women had higher age-specific incidence in all age groups compared with non-Aboriginal women, although differences were not statistically significant in the youngest and oldest age groups. For bowel cancer, Aboriginal people had higher age-specific incidence compared with non-Aboriginal people, significantly higher in those aged 40–49 and ≥60 years, as indicated by the IRRs. For cervical and bowel cancer, differences in cancer incidence by Aboriginal status across age categories were not significant (all p values >0.05) indicating age gradients were largely parallel.
Discussion Aboriginal people were younger at diagnosis compared with non-Aboriginal people, reflecting the younger age distribution of the Aboriginal population. Higher proportions of breast and bowel cancers were diagnosed before the screening age range in Aboriginal compared with non-Aboriginal people. This raises the question whether increased capture of cancers earlier would be gained by commencing screening at a younger age in Aboriginal people. Other factors to consider include effectiveness and cost-effectiveness of screening by age and potential for increased false positive and false negative results . All things considered equal, the same principles should determine the screening target age for Aboriginal and non-Aboriginal people. Compared with non-Aboriginal people, Aboriginal people had higher age-specific breast and bowel cancer incidence rates in older age groups (60+ years for breast and 40–49 and 60+ years for bowel, respectively), although differences in rates by Aboriginal status by age were statistically significant only for breast cancer. Therefore, age-specific incidence rates do not indicate the need for lowering the screening target age for Aboriginal people. That said, genotype incidence rates are affected by current screening practices, including lower breast and bowel cancer screening rates in Aboriginal people . The need of increasing participation of Aboriginal people in existing screening programs is acknowledged.