Is radiation therapy an effective treatment for DCIS?
Usually not. Evidence suggests that it is not of benefit in low-grade DCIS and has little impact on high-grade lesions. Radiation therapy does have a modest benefit for intermediate grade lesions where the margins are absolutely clear. The benefit in that group is small- about 14% at 7 years of follow-up. However, the benefit of radiation therapy only lasts a relatively short period of time. There’s a great deal of benefit for the first 5 years. But, between 5 and 10 years, the benefit wears off. During the next 5 years it rises rapidly and at 10 years, the results starts to approach those of lumpectomy alone. Radiation works better on highly active metabolic tissue such as invasive cancer.
