Cambridge Radiotherapy Index helps select patients who will benefit from radiotherapy following mastectomy for early breast cancer.

Radiotherapy is used in certain patients following mastectomy for early breast cancer and can reduce the chance of local recurrence and improve survival. At present post-mastectomy radiotherapy is routinely recommended for patients who have a high chance of local recurrence based on the size of the tumour, the number of positive lymph nodes and the proximity of the tumour to the underlying muscle or the overlying skin. The use of post-mastectomy radiotherapy in patients at intermediate risk of local recurrence is less clear and is currently being assessed in the randomised Supremo trial and may take several years to reach a conclusion.

 The Cambridge post-mastectomy radiotherapy index was constructed and introduced in 1999 by Professor Gordon Wishart and Dr Charles Wilson from the Cambridge Breast Unit, UK to help select appropriate patients for radiotherapy based on tumour size, tumour grade and lymph node status. The 10-year experience using this index was published in the journal Radiotherapy & Oncology in January 20141. Of 898 patients treated by mastectomy for early invasive breast cancer between 1999 and 2009, only 14 (1.6%) developed an isolated local recurrence within 5 years of surgery. 5-year local recurrence rates were exactly the same (2%) for patients in both low risk and intermediate risk groups, suggesting that the use of radiotherapy in some patients at intermediate risk has reduced the risk to the same as low risk patients. The Cambridge post-mastectomy radiotherapy index therefore appears to be a useful tool for selecting which patients should be treated by radiotherapy following mastectomy.

 1. Mukesh MB, Duke S, Parashar D, Hughes-Davis L, Wishart G, Coles C, Wilson C. The Cambridge post-mastectomy radiotherapy (C-PMRT) index: a practical tool for patient selection. Radiother Oncol. 2014; 110: 461-66.