By Karuna Jaggar, Executive Director
Throughout the day on Wednesday, the first full day of the annual San Antonio Breast Cancer Symposium (SABCS), the emerging theme was less can be more for patients. In this session we learned that skipping radiation for some low-risk breast cancer patients may be a viable option, resulting in comparable overall survival and leaving the patient without radiation-related harms.
In the opening plenary lecture on Wednesday morning, Dr. Jay R. Harris (Dana Farber Cancer Center) argued that there are some patients who can safely omit radiation after lumpectomy. Data has shown that lumpectomy plus radiation is comparable to mastectomy. While there are many advantages to breast-conserving surgery (lumpectomy) for women, the short and long term harms from radiation are not insignificant. Now there is data suggesting that some patients can safely avoid radiation therapy after surgery.
Previous data already established that for older patients with ER+ breast cancer, treated with tamoxifen, it is reasonable to omit radiation. Even though there is a somewhat higher risk of recurrence without radiation, the absolute risk is very low to begin with and treating with radiation offers no benefit in terms of overall survival. Furthermore, for those women who have a recurrence, they are still eligible for a second lumpectomy because they were not treated with radiation the first time.
Radiation can reduce the risk of local recurrence and of death, although (counter-intuitive for many) the data shows that local recurrence did not influence survival outcomes. A recent meta-analysis of breast-conserving therapy with or without radiation shows that radiation reduces the relative risk of recurrence by about half. Furthermore, radiation reduces the risk of death by 1/6th. But for women with a low overall risk, the absolute benefit of adding radiation can be very small.
Over more than four decades, the 5-year risk of local recurrence has declined from around 10% in the 1970s to about 2% today. (Dr. Harris notes that it’s ironic that as breast-conserving therapy gets better, more patients are choosing mastectomy.)
The main factor in predicting local recurrence is the biologic subtype of the tumor. Age (or lack thereof) is also a risk factor; the youngest patients had the highest rates of local recurrence but it is less of a determining factor than tumor type. The highest rates of recurrence are HER2+ breast cancers that have not been treated with Herceptin, followed by triple negative breast cancers, which have a four-fold risk of recurrence compared to lowest risk luminal A breast cancers.
Dr. Harris, who recently retired from Dana-Farber, noted the institution will start offering hormone therapy alone to women age 50-75 with small (low grade), node negative luminal A breast cancers ; these women will have the option of avoiding radiation. This is good news for women who have concerns about the immediate and longer term harms of radiation.