In the landscape of breast cancer, Ductal Carcinoma In Situ (DCIS) represents a non-invasive condition where abnormal cells are confined to the milk ducts. While DCIS is not life-threatening, it indicates an increased risk for developing invasive breast cancer in the future. Treatment for this stage 0 diagnosis typically involves breast-conserving surgery, known as a lumpectomy, to remove the affected tissue. Following the surgery, radiation therapy is often recommended to reduce the risk of the cancer returning in the same breast, making the number of radiation treatments a central question for many patients.
The Purpose of Radiation After DCIS Surgery
Radiation delivered after a lumpectomy is a form of adjuvant therapy used to increase the chances of long-term success. The goal is to eliminate any microscopic DCIS cells that might have been left behind after surgical removal, even when the surgeon aims for clear margins. By destroying these residual cells, radiation therapy significantly reduces the risk of a local recurrence in the treated breast. Clinical trials show that adding radiation therapy can cut the risk of the DCIS or an invasive cancer returning by about half. This reduction in local recurrence is the primary benefit, helping patients avoid the need for a second surgery or a mastectomy in the future.
Whole Breast Irradiation Schedules
Whole Breast Irradiation (WBI) is the most common form of radiation therapy used after a lumpectomy, treating the entire breast to minimize recurrence. The historical standard was conventional fractionation, which involved 25 to 35 fractions delivered over five to seven weeks. The current preferred approach is hypofractionation, which uses a higher daily dose for a shorter overall treatment course of 15 to 20 fractions, completed over three to four weeks. Studies show this condensed schedule is equally effective at preventing local recurrence, often with better cosmetic outcomes and patient convenience. Patients with certain characteristics, such as high-grade disease, may also receive a “boost” of 5 to 8 extra treatments to the immediate area where the tumor was removed.
Accelerated Partial Breast Irradiation
Accelerated Partial Breast Irradiation (APBI) is a distinct and significantly shorter alternative to WBI. APBI focuses the radiation dose only on the tissue immediately surrounding the surgical cavity, where most recurrences tend to originate. This localized approach allows for a substantially accelerated treatment schedule. The number of treatments in APBI ranges from 5 to 10 fractions delivered over a short period, sometimes as quickly as one to five days. APBI can be delivered using various techniques, including external beam radiation or brachytherapy, which involves temporarily placing radioactive sources directly into the surgical cavity.
Patient and Tumor Factors Guiding Treatment Choice
The final number of radiation treatments is determined by a personalized assessment of both tumor characteristics and the patient’s health profile. Tumor factors include the size and grade of the DCIS, necrosis presence, and the status of the surgical margins; high-grade DCIS or very close surgical margins may make a patient a better candidate for WBI with a boost, or sometimes exclude them from an APBI option. Patient-specific factors, such as age and overall health, also influence the decision. Older patients with smaller, low-grade DCIS may sometimes skip radiation entirely if genomic tests suggest a very low risk of recurrence. Practical considerations, like the ability to adhere to a daily, multi-week schedule, may favor the shorter APBI or hypofractionated WBI options, and the final treatment plan is a shared decision based on national guidelines.