Breast screening participation and degree of spread of invasive breast cancer at diagnosis in mental health service users: A population linkage study.

BACKGROUND: Women living with mental health conditions may not have shared in improvements in breast cancer screening and care. No studies have directly examined the link between reduced screening participation and breast cancer spread in women using mental health (MH) services. METHODS: Population-wide linkage of a population cancer register, BreastScreen register, and mental health service data set in women aged 50 to 74 years in New South Wales, Australia, from 2008 to 2017. Incident invasive breast cancers were identified. Predictors of degree of spread (local, regional, metastatic) at diagnosis were examined using partial proportional odds regression, adjusting for age, socioeconomic status, rurality, and patterns of screening participation. RESULTS: A total of 29 966 incident cancers were identified and included 686 (2.4%) in women with MH service before cancer diagnoses. More than half of MH service users had regional or metastatic spread at diagnosis (adjusted odds ratio, 1.63; 95% CI, 1.41-1.89). MH service users had lower screening participation; however, advanced cancer was more common even when adjusting for screening status (adjusted odds ratio, 1.53; 95% CI, 1.32-1.77). Advanced cancer was more common in women with severe or persistent MH conditions. CONCLUSIONS: Low screening participation rates explain only small part of the risk of more advanced breast cancer in women who use MH services. More study is needed to understand possible mechanisms contributing to more advanced breast cancer in women living with MH conditions. Health systems need strategies to ensure that women living with MH conditions enjoy population gains in breast cancer outcomes.

Breast cancer screening participation in women using mental health services in NSW, Australia: a population study.

PURPOSE: Population screening programs have contributed to reduced breast cancer mortality, but disadvantaged or vulnerable groups may not have shared these improvements. In North American and European studies, women living with mental health conditions have reduced breast screening rates. There are no current Australasian data to support health system planning and improvement strategies. METHODS: The New South Wales (NSW) BreastScreen program offers free screening to NSW women aged 50-74. We compared 2-year breast screening rates for mental health service users (n = 33,951) and other NSW women (n = 1,051,495) in this target age range, after standardisation for age, socioeconomic status and region of residence. Mental health service contacts were identified through linkage to hospital and community mental health data. RESULTS: Only 30.3% of mental health service users participated in breast screening, compared with 52.7% of other NSW women (crude incidence rate ratio 0.57, 95% CI 0.56-0.59). Standardisation for age, socioeconomic disadvantage or rural residence did not alter this screening gap. Around 7000 fewer women received screening than would be expected from comparable population rates. Screening gaps were largest in women over 60 and in socioeconomically advantaged areas. Women with severe or persistent mental illness had slightly higher screening rates than other mental health service users. CONCLUSIONS: Low breast cancer screening participation rates for NSW mental health service users suggest significant risk of later detection, possibly leading to more extensive treatment and premature mortality. Focussed strategies are needed to support greater breast screening participation for NSW women who use mental health services.