Dose homogeneity with intensity-modulated radiotherapy reduced the risk of skin telangiectasia, resulting in superior overall cosmesis for early breast cancer patients in a 5-year single-center trial.
"This study should act as an evidence-based lever for change for radiotherapy centers that have yet to implement breast IMRT (intensity-modulated radiotherapy)," wrote Dr. Mukesh B. Mukesh of Cambridge (England) University Hospitals National Health Service Foundation Trust, and colleagues.
The Cambridge Breast IMRT Trial randomized 1,145 women with early breast cancer to receive either standard radiotherapy or simple intensity-modulated radiotherapy (IMRT), which uses additional irradiation fields to smooth out the dose to the target area.
In the multivariate analysis, significantly fewer patients in the IMRT arm had suboptimal overall cosmesis (OR, 0.65; 95% CI, 0.44 to 0.98; P = .038) and skin telangiectasia (OR, 0.57; 95% CI, 0.34 to 0.95; P = .031), according to data published online in the Journal of Clinical Oncology (doi:10.1200/JCO.2013.49.7842). However the two groups did not significantly differ based on photographically assessed breast shrinkage, clinically assessed edema, tumor bed induration or pigmentation, according to the researchers.
Also, there was no statistically significant difference in 5-year locoregional recurrence and overall survival rates.
Surgical cosmesis had a significant impact on outcomes, as patients with moderate to poor baseline surgical cosmesis were more likely to have suboptimal final cosmesis (OR, 8.15; 95% CI, 6.09 to 10.92; P < .001), tumor bed induration (OR, 1.80; 95% CI, 1.44 to 2.26; P < .001), and photographically assessed breast shrinkage (OR, 1.54; 95% CI, 1.21 to 1.96; P < .001).
Factors such as large breast volume and tumor bed boost were also associated with an increased risk of suboptimal overall cosmesis. Older patients, and those with postoperative breast infections, large breast volume, and tumor bed boost, were also more likely to develop skin telangiectasia.
The patients enrolled in the study all had operable unilateral, histologically confirmed invasive breast cancer or ductal carcinoma in situ requiring radiotherapy after breast-conservation surgery.
All patients were assigned a standard radiotherapy plan. Those with satisfactory dose homogeneity were not randomly assigned but treated with standard radiotherapy and followed up as if randomly assigned, while those whose plan had significant dose inhomogeneity (defined as > or = 2 cm3 volume receiving greater than 107% of the prescribed dose) were randomized between standard radiotherapy (control arm) and simple IMRT.
There were a significant number of patient withdrawals at the 5-year analysis due to factors such as travel difficulties, social issues, and personal choice, and cancer-related factors.
The researchers declared having no conflicts of interest.