Tailoring Decisions on Radiation Therapy for DCIS
Decisions about radiotherapy after breast-conserving surgery for ductal carcinoma in situ (DCIS) can be tailored on the basis of patient factors, tumor biology, and the prognostic score, according to research published in the Journal of Clinical Oncology.1 This set of easily measurable factors can predict the magnitude of survival benefit offered by radiation therapy after breast cancer surgery.
DCIS is expected to be diagnosed in about 60 000 patients in the United States this year. It is not an invasive form of cancer and its 10-year survival rate is over 98%. However, its incidence has dramatically increased over the past 30 years. Better determining risk of recurrence and mortality could help clinicians and patients to neither overtreat nor undertreat the disease.
"DCIS has a very low breast cancer mortality, which means that as an oncology community, we must be cognizant of overtreatment," said co-senior author Mehra Golshan, MD, Al-Tuwaijri Family Distinguished Chair of Surgical Oncology at Dana-Farber/Brigham and Women's Cancer Center in Boston, Massachusetts.
"Radiation therapy after breast cancer surgery has become a widely accepted treatment option for patients undergoing breast conserving therapy (or lumpectomy) with DCIS. Our results provide information that can guide individual treatment options, and better predict survival benefit from radiation therapy based on an individual's case."
This retrospective, longitudinal study examined data from more than 32 000 patients treated for DCIS, including more than 20 000 who received radiation therapy and breast cancer surgery and more than 11 000 who received breast cancer surgery alone. Both groups had low rates of breast cancer mortality at 10 years: 1.8% for the group that received radiation therapy and 2.1% for the group that did not.
Each patient was assigned a validated prognostic score between 0 and 6 based on 3 risk factors: nuclear grade (a measure of how abnormal cells look under a microscope); patient's age; and tumor size. Scores were higher for patients with a higher nuclear grade, younger age, and/or larger DCIS and vice versa. Past studies have shown that a patient's prognostic score can predict breast cancer recurrence, but such scores had not previously been used to assess the effectiveness of treatment decisions on long term breast cancer survival.
For the patients with higher prognostic scores, the researchers found that radiation therapy conferred a significant survival benefit. Breast cancer mortality was reduced by nearly 70% for those with scores of 4 or 5. However, for patients with low scores, breast cancer mortality did not have a significant difference with or without radiotherapy.
"Using 3 factors that are routinely measured, we can predict whether there will be a survival benefit or no survival benefit for patients receiving radiation therapy," said lead author Yasuaki Sagara, MD, of the BWH Department of Surgery and Dana Farber/Brigham and Women's Cancer Center and Chief of Breast Oncology at Hakuaikai Medical Cooperation in Japan, "Our finding suggests, for the first time, that patients with more aggressive cancer who are at higher risk may actually live longer if they are treated with radiation therapy."
Though radiation therapy provides negligible survival benefit for low risk patients, the authors noted that other studies have found that radiation therapy can reduce the rate of local recurrence even among patients with low prognostic scores. In the face of such complexities, the authors recommend thorough counseling about the risks and benefits of radiation therapy for informed decision making.
1. 1. Sagara Y1, Freedman RA2, Vaz-Luis I, et al. Patient prognostic score and associations with survival improvement offered by radiotherapy after breast-conserving surgery for ductal carcinoma in situ: a population-based longitudinal cohort study [publishedd online ahead of print February 1, 2016]. J Clin Oncol. doi: 10.1200/JCO.2015.65.1869.