Background
A policy of centralisation of symptomatic breast services was implemented in Ireland in 2009. This included centralising surgical services in eight Symptomatic Breast Disease (SBD) units and introduction of evidence-based GP referral guidelines for suspected cancer.
Aim
To investigate the factors influencing GP referrals to SBD units in Ireland.
Methods
Four individual studies were conducted in a mixed-methods design. Study 1 analysed breast cancer referral and detection rates. Studies 2 and 3 comprised in-depth interviews with 9 cancer centres (hospitals) and 28 randomly-selected GPs to explore factors influencing GP referral. The impact of centralisation on referral patterns was analysed in Study 4, using the national cancer database.
Results 
Referrals to breast units in Ireland increased by almost 60% in five years, without a corresponding increase in breast cancers detected. Reasons for referral included mastalgia (15%) and family history (9%). Clinical and non-clinical factors were identified as influencing referrals, such as;   GP factors, including fear of missing a cancer and risk aversion Resources, including ease of access to breast clinics and high quality of the service Social influences, such as patient anxiety, media and patient expectations. 
A significant increase was identified in analysis of national data of the proportion of patients having their diagnosis and surgery at designated cancer centres rather than non-cancer centres, indicating a high level of policy implementation. Cox proportional-hazards regression showed prompt access for GP referrals.
Conclusions 
This is the first study to examine the effects of centralisation of breast cancer services in Ireland. The results provide useful evidence on the impact and effectiveness of this policy initiative and show early indicators of success.
GP referrals are influenced by GP, health service, social and clinical factors, which can be both social and contextual in nature. GP beliefs about consequences coupled with social influences are challenging barriers to address and will require multifaceted interventions to overcome