Nonbreast cancer incidence, treatment received and outcomes: Are there differences in breast screening attendees versus nonattendees?

While reductions in breast cancer mortality have been evident since the introduction of population-based breast screening in women aged 50-74 years, participation in cancer screening programs can be influenced by several factors, including health system and those related to the individual. In our study, we compared cancer incidence and mortality for several cancer types other than breast cancer, noncancer mortality and patterns of treatment amongst women who did and did not participate in mammography screening. All women aged 50-65 years enrolled on the Queensland Electoral Roll in 2000 were included. The study population was then linked to records from the population-based breast screening program and private fee-for-service screening options to establish screened and unscreened cohorts. Diagnostic details for selected cancers and cause of death were obtained from the Queensland Oncology Repository. We calculated incidence rate ratios and hazard ratios comparing screened and unscreened cohorts. Among screened compared to unscreened women, we found a lower incidence of cancers of the lung, cervix, head and neck and esophagus and an increase in colorectal cancers. Cancer mortality (excluding breast cancer) was 35% lower among screened compared to unscreened women and they were also about 23% less likely to be diagnosed with distant disease. Screened compared to unscreened women were more likely to receive surgery and less likely to receive no treatment. Our study adds further to the population data examining outcomes among women participating in mammography screening.