Evaluating MRI Response in Breast Tumours Treated with Radiotherapy – Can Apparent Diffusion Co-efficient (ADC) Predict Long Term Response?

Motivation: Research on how primary breast tumours in situ respond to radiotherapy is very limited, though increasingly relevant as neo-adjuvant radiotherapy trials expand, requiring accurate and sensitive monitoring of therapy response. Goal(s): To evaluate MRI response in breast tumours treated with radiotherapy and assess whether ADC values or their changes predict long-term outcomes. Approach: Twenty-five patients underwent radiotherapy to in-situ breast tumours with the aim of long-term control. CE-DW-MRI was performed at baseline and 2W, 6M and 12M post-radiotherapy. Results: Early ADC changes at 2-weeks post-radiotherapy correlated more strongly with long-term response than later ADC changes. Impact: Early assessment of ADC on DW-MRI after radiotherapy treatment could predict long term responses in breast tumours. This could allow future personalisation of radiotherapy doses based on baseline ADC values of tumours.