Although the first studies highlighting the importance of the tumour inflammatory cell infiltrate were reported more than 80 years ago, the prognostic value of this response in breast cancer is still controversial. With the realisation of the importance of the inflammatory response in determining tumour progression there has been renewed interest in establishing the relationship between the type, density and location of inflammatory cell infiltrate and survival in patients with primary operable breast cancer. The aim was to undertake a systematic review of the literature examining the evidence for the role of the tumour inflammatory cell infiltrate in predicting recurrence and survival in patients with primary operable breast cancer. A systematic review of published papers up to September 2011 was undertaken according to a pre-defined protocol (Fig. 1). A total of 66 independent studies (34,086 patients) were identified. It can be concluded from the review that despite the large number of studies and considerable effort over an extended period, the relationship between different aspects of tumour inflammatory cell infiltrate and outcome in primary operable breast cancer remains unclear. This is in large part due to the absence of methodological validation, underpowered studies (small sample size and sample subtype heterogeneity, insufficient follow-up) and the absence of validation datasets. Therefore, although there are tantalising examples of the potential of the tumour inflammatory cell infiltrate to improve risk stratification patients with operable breast cancer (personalised care), this has not yet been realised. Future studies with standardised methodology, large and homogenous groups, sufficient follow-up and validation datasets should be undertaken to unlock the potential of the tumour inflammatory infiltrate to predict outcome in patients with primary operable breast cancer.
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