Breast cancer outcome good with modified radiotherapy technique
MedWire News: A simultaneous integrated boost-intensity-modulated radiation therapy (SIB-IMRT) technique that reduces treatment duration has a favorable toxicity profile and excellent locoregional control in breast cancer patients, US researchers report.
“Providing a greater dose per fraction to the resection cavity than to the remainder of the breast allows the traditional sequential boost to be eliminated, thereby shortening the treatment course duration,” explain Karen Godette and colleagues, from Emory University School of Medicine in Atlanta, Georgia.
They began using IMRT with a SIB to the resection cavity following conservative surgery for Stage 0 to III breast cancer in 2003.The team treated 356 breasts in 354 patients between 2003 and 2006. Of these, 282 were invasive breast cancer, and 74 were ductal carcinoma in situ (DCIS)
Most women (89%) were treated with a fractionation schedule that delivered 1.8 Gy to the ipsilateral breast tissue and 2.14 Gy to the resection cavity, yielding a breast dose of 45 Gy (25 fractions) and cavity dose 59.92 Gy (28 fractions). This dose was biologically equivalent for tumor control to 45 Gy to the breast with a sequential 16-Gy boost (33 fractions).
For left breast radiation, the median volume of heart receiving 15 Gy or more (V15) was 2.9%, and the left ventricular V15 was 1.7%.
The researchers found that during a median follow-up of 33 months, acute skin toxicity was Grade 1 in 57% of cases, Grade 2 in 43%, and Grade 3 in less than 1%.
For invasive breast cancer, the 3-year overall survival rate was 97.6% and the risk for any locoregional recurrence was 2.8%. For DCIS, 3-year overall survival was 98% and the risk for locoregional recurrence was 1.4%.
An assessment of global breast cosmesis at a minimum of 3 years of follow-up was available in 142 (40%) cases. Among these, 96.5% were judged as good or excellent, while 3.5% were considered fair. No patients were judged to have a poor cosmetic outcome.
Writing in the International Journal of Radiation Oncology Biology Physics, Godette and team conclude that “breast SIB-IMRT reduced treatment duration by five fractions with a favorable acute toxicity profile and low cardiac dose for left breast treatment.
“At 3 years, locoregional control was excellent, and initial assessment suggested good or excellent cosmesis in a high percentage of evaluable patients,” they add.
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By Laura Dean