Pathological complete response in locally advanced breast cancer: determinants and predictive significance

Neoadjuvant chemotherapy is now the standard approach for most large breast cancers including locally advanced cancers of the breast. The majority of patients respond satisfactorily to chemotherapy with effective downsizing of tumours to consider breast conservation surgery. Pathological complete response (pathCR) is known to be a strong predictor of good outcome; however, many factors are known to influence the extent of response to chemotherapy. It has been observed that smaller the tumour, better is the response achieved in contrast to larger and locally advanced tumours where only one-third may respond well enough to merit breast conservation. Various other clinical, biological and molecular factors are also being evaluated as effective predictors of chemosensitivity. Most of these are either not easily available for all patients in developing countries or are overtly expensive and not applicable for all patients.

We evaluated the clinical and pathological predictors of response to chemotherapy in 1402 women with locally advanced breast cancer.

There was a higher rate of pathCR in smaller tumours, younger women and ER-negative as well as triple negative tumours. The presence of ductal carcinoma in situ (DCIS) and lymphatic and vascular invasion (LVI) were associated with lower pathCR.

In the absence of ready availability of expensive molecular and genomic assays, clinical parameters and standard histopathological variables can also be useful indicators of response to neoadjuvant chemotherapy. Additionally, they can help identify those who could be eventually conserved or have a better outcome.