Intensity-Modulated Radiotherapy Associated With Superior Overall Cosmesis at 5 Years in Patients With Early Breast Cancer
Interim results of the Cambridge Breast Intensity-Modulated Radiotherapy trial indicated that intensity-modulated radiotherapy was associated with significantly reduced skin telangiectasia compared with standard radiotherapy at 2 years in patients with early breast cancer. The trial included a preplanned 5-year analysis to determine whether improved dose homogeneity with simple intensity-modulated radiotherapy translates into clinical benefits from reduced late breast tissue toxicity. As reported in Journal of Clinical Oncology by Mukesh B. Mukesh, MBBS, FRCR, of Cambridge University Hospitals National Health Service Foundation Trust, and colleagues, intensity-modulated radiotherapy was associated with improved overall cosmesis and reduced skin telangiectasia at 5 years.
Study Details
The trial included women with operable unilateral, histologically confirmed invasive breast cancer (T1-3, N0-1, M0) or ductal carcinoma in situ requiring radiotherapy after breast-conservation surgery. Standard tangential plans of 1,145 patients were analyzed and 815 patients with inhomogeneous plans (≥ 2 cm3 receiving > 107% of prescribed dose: 40 Gy in 15 fractions over 3 weeks) were randomly assigned to standard radiotherapy (n = 404) or replanned with simple intensity-modulated radiotherapy (n = 411); 330 patients with satisfactory dose homogeneity were treated with standard radiotherapy and underwent the same follow-up as the randomly assigned patients. Breast tissue toxicities were assessed at 5 years using validated methods, including photographic assessment for overall cosmesis and breast shrinkage compared with baseline preradiotherapy photographs and clinical assessment for telangiectasia, induration, edema, and pigmentation.
Cosmesis Outcomes
Five-year breast tissue toxicity outcomes were available for 654 patients (57%), including 228 in the intensity-modulated radiotherapy group and 237 in the randomized control radiotherapy group. On univariate analysis, intensity-modulated radiotherapy was associated with significantly reduced risk of suboptimal overall cosmesis (odds ratio [OR] = 0.68, P = .027) and skin telangiectasia (OR = 0.58, P = .021). No significant differences were observed in breast shrinkage (OR = 0.79, P = .21), breast edema (OR = 0.74, P = .18), tumor bed induration (OR = 0.76, P = .11), or pigmentation (OR = 0.80, P = .42). On multivariate analysis adjusting for factors significantly associated with late toxicity after radiotherapy on univariate analysis (P < .1), the benefit of intensity-modulated radiotherapy was maintained for both overall cosmesis (OR = 0.65, P = .038) and skin telangiectasia (OR = 0.57, P = .031).
Other Significant Factors
Large breast volume (P = .02), poorer baseline surgical cosmesis (P < .001), and tumor bed boost (P = .003) were also associated with suboptimal overall cosmesis on multivariate analysis. Skin telangiectasia was also associated with older age (P = .005), postoperative breast infection (P < .001), increasing breast volume (P < .001), and tumor bed boost (P = .023). Patients with moderate to poor baseline surgical cosmesis were at significantly increased risk of suboptimal final cosmesis (OR = 8.15, P < .001), tumor bed induration (OR = 1.80, P < .001), and breast shrinkage (OR = 1.54, P < .001).
There were no differences in 5-year locoregional recurrence (1.35% vs 2.56%, P = .36) or 5-year overall survival (91.7% vs 92.5%), P =.88) between the intensity-modulated radiotherapy and control groups.
The investigators concluded: “Improved dose homogeneity with simple [intensity-modulated radiotherapy] translates into superior overall cosmesis and reduces the risk of skin telangiectasia. These results are practice changing and should encourage centers still using two-dimensional [radiotherapy] to implement simple breast [intensity-modulated radiotherapy].”
Charlotte E. Coles, MRCP, FRCR, PhD, of Cambridge University Hospitals National Health Service Foundation Trust, is the corresponding author for the Journal of Clinical Oncology article.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
