Radiation Therapy for Inoperable Breast Cancer

(DEFINE Trial)

This trial explores whether adding radiation therapy to standard breast cancer medications can slow or stop the progression of the disease. It targets individuals with advanced breast cancer that is inoperable or for those who opt out of surgery. Participants will receive whole breast radiation with simultaneous integrated boost (WB-SIB), focusing on the main tumor and, in some cases, nearby lymph nodes. Those with inoperable cancer or who have declined surgery may find this trial suitable.

As an unphased trial, this study provides a unique opportunity to contribute to innovative research that could lead to new treatment options for advanced breast cancer.

The trial allows you to continue taking certain medications like endocrine therapy, HER2-targeted therapy, or immunotherapy. However, other systemic therapies are not allowed during the trial.

Research shows that whole breast radiation with a simultaneous integrated boost (WB-SIB) is generally manageable for patients. Studies have found that this method can cause less skin irritation compared to other techniques, resulting in fewer side effects like redness or soreness.

For those receiving WB-SIB to both the main breast tumor and nearby lymph nodes, the safety remains consistent. This method also shortens the overall treatment time, which many patients find beneficial.

Researchers are excited about using whole breast radiation with a simultaneous integrated boost (WB-SIB) because it targets the primary breast tumor more precisely. Unlike standard radiation therapy options, which often treat the entire breast uniformly, WB-SIB delivers a higher dose of radiation directly to the tumor and, in some cases, the nearby lymph nodes, potentially sparing healthy tissue and reducing side effects. This targeted approach could improve outcomes for patients with both node-negative and node-positive inoperable breast cancer by offering a more focused and aggressive treatment option.

This trial will compare two approaches using whole breast radiation with a simultaneous integrated boost (SIB) for treating inoperable breast cancer. Studies have shown that SIB effectively treats breast cancer, resulting in high rates of local control and improved survival. For instance, one study reported a 93% survival rate and a 92% local control rate over three years. In this trial, one group will receive SIB targeting only the primary breast tumor, while another group will receive SIB targeting both the primary breast tumor and the ipsilateral axillary lymph nodes. For patients whose cancer has spread to the lymph nodes, adding SIB to treat these areas appears promising, although researchers continue to gather more data on its effectiveness. Overall, these treatments show strong potential for effectively managing breast cancer.¹²³⁶⁷