Study: Lumpectomy cavity volume decreases during whole-breast irradiation

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Patients who undergo lumpectomy will likely have their lumpectomy cavity decrease in volume during whole-breast irradiation, according to a study in this month's International Journal of Radiation Oncology*Biology*Physics.

Majid M. Mohiuddin, MD, and colleagues from the department of radiation oncology at the University of Maryland School of Medicine in Baltimore, sought to determine whether the lumpectomy cavity decreases in volume during whole-breast radiotherapy and what factors influence the decrease.

To answer this question, the researchers prospectively enrolled 43 women with 44 breast lesions in their study. The patients underwent lumpectomy followed by a CT simulation within 60 days of the surgery.

After 21-23 radiation treatments, a second planning CT simulation was done and the lumpectomy cavity was contoured.Lumpectomy cavity volumes were then compared between the first CT simulation and the second.

The authors found that patients undergoing lumpectomy “almost always” had a decrease in their lumpectomy cavity during whole-breast radiation therapy and that there was a correlation between the initial lumpectomy cavity volumes and a decrease in volume on repeat CT simulation.

Mohiuddin and colleagues concluded that evaluating patients for this change can lead to decreased doses of radiation to the remaining breast and surrounding area when delivering a small-field boost and that CT simulation should be considered in patient's with cavities near critical structures.