Short Course Radiation Treatment for Breast Cancer

Doris R. Brown, MD, PhD

Assistant Professor, Radiation Oncology

Wake Forest Baptist Medical Center

Comprehensive Cancer Center

When it is determined by the patient with breast cancer and physician that the best course of treatment is radiation therapy, there are two options for consideration: treating either the whole breast or treating only part of the breast. With that determination, active research and advancements in the field focuses on lessening the burden of radiation treatment while still maintaining acceptable cosmetic outcomes.

If whole breast radiation is considered, the treatment is administered externally. Traditional (or conventionally fractionated) whole breast radiation treatment for breast cancer involves women receiving 25 to 33 daily treatments (Monday-Friday) over 5 to 6 weeks. Although this is a well-tolerated treatment, the inconvenience of this regimen sometimes limits a woman’s ability to undergo this potentially lifesaving adjuvant therapy.

If partial radiation is chosen, only the area of the breast that is adjacent to the surgical bed is treated. Partial breast radiation can be delivered either externally or internally with a combination of catheters and/or balloon (brachytherapy). This treatment is given twice daily over 1 week with high doses each day, called accelerated partial breast irradiation (aPBI). Patient selection for aPBI is critical to ensure good cosmetic outcomes and limit toxicity, including the need for a mastectomy due to complications from treatment.

Wake Forest’s Comprehensive Cancer Center Breast Cancer Program offers aPBI as one of the treatment options. Tumor size, location, and patient factors are taken into consideration before treatment with brachytherapy. Patients are counseled that the use of aPBI will not decrease the risk of breast cancer in other parts of the same breast and that they will need to continue close follow up in our Breast Survivor’s Clinic.

Hypofractionated Radiation

Studies that have looked at using aPBI in older patients have resulted in its cautionary use, as women treated with aPBI were twice as likely to need to undergo mastectomy because of recurrent cancer in the breast, chronic pain, or poor cosmesis. The results of recent studies suggest that treating only the area around the initial cancer may not decrease the chance of the cancer coming back compared with treating the whole breast.In the past several years, large randomized clinical trials conducted in countries with limited healthcare resources have shown that we may be able to shorten the course of radiation for selected individuals. These data show that there is little difference in the risk of local breast cancer recurrence or survival with 10 years of follow-up.

These shorter or hypofractionated radiation courses involve delivery of a similar amount of radiation to conventionally fractionated courses in fewer treatments, which means that each treatment is approximately 33% larger. This short course of breast radiation has been offered at Wake Forest Baptist Medical Center — Comprehensive Cancer Center routinely for women that meet recommendations from the American Society of Radiation Oncology.

Skin Toxicity

The guidelines support the equivalence of hypofractionated whole breast irradiation in women that meet all of the following criteria: are 50 years or older at diagnosis, T1-2 tumors with no positive nodes, have not undergone systemic chemotherapy, and have breast sizes that allow for safe doses of radiation to the breast. Another important factor to consider is that with higher doses of radiation each day, there may be a greater risk of long-term damage to normal healthy tissues. For breast cancer survivors, the critical organ at risk is the heart, particularly for left-sided survivors. A comprehensive program to protect the heart from radiation treatment is ongoing at Wake Forest.Although some reports have suggested that the shorter courses of treatment are better tolerated with fewer side effects or skin reactions, in our experience women undergoing these shorter treatment courses have the same if not greater skin toxicity. One limitation of the studies was that data about skin toxicity was not collected at the times when patients are at highest risk.

It takes approximately 21 days for the basal layer of skin cells that are affected by radiation treatment to mature and reach the superficial layers of the skin. Because of this, a woman that has completed treatment in 3 weeks may not have any visible skin reaction while under treatment. She will, however, develop skin changes and risk for radiation dermatitis over the next 2 weeks after completion of therapy. We routinely monitor all patients treated with hypofractionated regimens with weekly skin checks until their skin changes have resolved. This has resulted in improved patient satisfaction as well as better longer term cosmetic outcomes.

Shorter courses of radiation may not be safe in young women, women with only pre-invasive disease, women with high-grade disease, large breasts, close or positive margins, those receiving systemic treatment with agents other than hormone therapy, or those women that need treatment of nodal areas at risk of residual disease.

Because of limitations in these studies, Wake Forest is participating in a national trial investigating the use of hypofractionated whole breast radiation in women with higher risk features as well as those who were underrepresented on the previous trials. Data from this study will not be available for several years. In the interim, Wake Forest continues to offer hypofractionated radiation treatment to selected patients.