Breast cancer recurrence low following intraoperative radiotherapy
MedWire News: Intraoperative radiotherapy (IORT) using low-kilovoltage (kV) X-rays during breast-conserving surgery (BCS) for breast cancer yields low recurrence and toxicity rates, German research shows.
"Recently, the concept of IORT during BCS has been introduced using linear accelerators, brachytherapy, or dedicated, mobile IORT devices generating fast electrons or low-energy X-rays," explain Frederik Wenz and colleagues from the University of Heidelberg, in Mannheim.
The team began using IORT at the University Medical Center Mannheim in 2002, and treated 155 stage T1 or T2 breast cancers in 154 women (median age 63 years) between then and 2007. IORT involved a tumor bed boost using 50-kV X-rays (20 Gy), followed by 46-50 Gy whole-breast external beam radiotherapy (EBRT).
Wenz and team report that during a median follow-up period of 34 months, 10 patients died, two had in-breast relapse, and eight developed distant metastases, resulting in a 5-year overall survival rate of 87.0% and a 5-year local relapse-free survival rate of 98.5%.
Three years after IORT, 79 patients were evaluated for late toxicity according to the Late Effects in Normal Tissues-Subjective, Objective, Management, and Analytic system.
The researchers found that only 5% of patients had grade 3 (on a scale of 0-3) fibroses of the tumor bed. In addition, skin toxicity was mild, with 6% of patients having telangiectases and 6% having hyperpigmentation.
"It is obvious from this and the other published trials of IORT as a tumor bed boost during BCS that the risk for local recurrence is relatively low and that the toxicity rates seem to be acceptable," write Wenz and co-authors in the International Journal of Radiation, Oncology, Biology, Physics.
They add: "Whether this higher-than-expected efficiency of IORT is due to lack of geographic miss, lack of tumor cell proliferation before and during radiotherapy, or effects of high single doses on the microenvironment including the microvasculature or cytokine pattern, remains unclear at present."
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By Laura Dean