Image-Guided Radiotherapy Technique May Save More Healthy Breast Tissue

A new study has been undertaken to validate whether a new sophisticated radiotherapy technique that uses imaging of titanium clips implanted during surgery can reduce side effects from breast cancer treatment.

The study, led by the Institute of Cancer Research (ICR; London, UK) and funded by the Efficacy and Mechanism Evaluation (EME) program, will compare image-guided radiotherapy (IGRT) with the conventional imaging technique. The study is a collaboration between the ICR, the Royal Marsden NHS [National Health Service] Foundation Trust (London, UK), Addenbrooke's Hospital NHS Trust (Cambridge, UKl), Clatterbridge Center for Oncology (Bebington, Wirral, UK), Ipswich Hospital NHS Trust (Suffolk, UK), Torbay Oncology Unit (Torquay, UK), and Royal Preston Hospital (Preston, Lancashire, UK).

A course of radiotherapy is frequently administered after surgery to kill any remaining breast cancer cells and reduce the risk of recurrence. Breast cancers typically recur close to the site of the original cancer (the tumor bed) so scientists are investigating options for delivering radiotherapy more precisely to this area, thereby reducing damage to surrounding tissue.

Currently, X-rays are used to direct radiotherapy treatment to the key area; however, they reveal only the position of surrounding organs and bones and not the exact location of the tumor bed. A safety margin must therefore be added to ensure the tumor bed always falls in the treatment area, with the result that a high dose of radiotherapy has to be given to twice as much healthy breast tissue as would otherwise be necessary.

In the latest study, known as IMPORT-IGRT, patients will have the walls of their surgical excision cavity marked with small titanium clips that can be seen in X-ray images. This will allow the tumor bed to be more precisely located and radiotherapy can be given to a smaller amount of breast tissue.

The study, led by Prof. Philip Evans, from the ICR, will measure the accuracy of radiotherapy that makes use of IGRT compared with conventional imaging. The scientists will assess how effective the IGRT technique is in reducing the volume of tissue treated at a high dose, and determine the consequent reductions in risk to normal tissue compared with the conventional technique.

"Our pilot studies suggest that safety margins around the tumor bed can be greatly reduced, leading us to expect a lower rate of long-term complications such as breast shrinkage, hardness, pain, and rib fracture,” said Prof. Evans. "In this study, we will be able to calculate exactly how much breast tissue we were able to spare and the implications this will have on side-effects.”

The study builds on an ongoing trial called IMPORT-HIGH, which is led by Prof. John Yarnold of the ICR and Dr. Charlotte Coles of Addenbrookes Hospital. IMPORT-HIGH is recruiting 840 women across the United Kingdom at average risk or above of breast cancer recurrence, to compare the effectiveness of conventional radiotherapy to the whole breast with radiotherapy more precisely targeted to the tumor bed using IGRT. IMPORT-IGRT's goal is to recruit 250 women from the original IMPORT-HIGH study.

The Efficacy and Mechanism Evaluation program supports later-phase, science-driven clinical trials and evaluative studies, which seek to determine whether a health intervention (e.g., a drug, diagnostic technique, or device) works, and in some instances, how or why it works.

Related Links:
Institute of Cancer Research
Royal Marsden NHS Foundation Trust
Addenbrooke's Hospital NHS Trust
Clatterbridge Center for Oncology