Is Radiation Necessary After Breast Cancer Surgery?
Ductal carcinoma in situ (DCIS) is a cancer that forms in the cells that line the milk ducts, and it accounts for 20% of new breast cancer diagnoses. The most common treatment is breast-conserving surgery to remove the cancerous tissue. While only a small percentage of women experience an invasive cancer event following surgery, radiation therapy is often recommended to reduce the chance of this outcome.
Radiation therapy for DCIS remains controversial. Previous studies suggest radiation reduces the local recurrence of cancer but does not necessarily increase the survival rate. In addition, clinicians have been unable to identify a high-risk group of patients who would benefit from this treatment based on physical and pathological factors, like tumor size and patient age. At the same time, radiation can have adverse effects on the surrounding tissue, as well as be detrimental to the psychological and financial well-being of the patient.
DCISionRT, a test developed by the pharmaceutical company Prelude Dx, was designed to determine the risk of DCIS breast cancer recurrence. The test examines tumor tissue for seven biomarkers (COX-2, FOXA1, HER2, Ki-67, p16/INK4A, PgR, and SIAH2). It has been validated in more than 1,400 women who have had breast-conserving surgery with or without radiation therapy.
The PREDICT Study
Local Principle Investigator Lonika Majithia, MD, along with Shawna C. Willey, MD, both with the Inova Schar Cancer Institute, contributed to the multi-institutional PREDICT study. They found that the DCISionRT test results provide an additional diagnostic tool to help clinicians identify the best treatment for DCIS patients following surgery.
PREDICT was a prospective, observational study conducted at 44 centers between February 2019 and July 2020. The study had two objectives 1) to identify the number of patients whose radiation recommendation changed after considering the DCISionRT test results and 2) to understand the key clinicopathological indicators that clinicians use to recommend radiation therapy without the DCISionRT test.
The Results
The study enrolled 539 women who ranged in age from 30 to 87. Before considering the DCISionRT test results, 374 women in the study received a recommendation for post-surgery radiation therapy. The DCISionRT test results led to net decrease in radiation recommendations for all clinicopathological factors, including tumor size, cell abnormality (grade), margin status and patient age, except patients older than 70.
The study also identified patients at elevated risk for invasive breast cancer and total recurrences, which was especially pronounced for patients in the high-risk subgroups defined by the Radiation Therapy Oncology Group 9804 and Eastern Cooperative Oncology Group E5194 criteria.
Because the study was designed to evaluate the role of DCISionRT test results in treatment decision-making, the impact on long-term clinical outcomes remains unknown. In addition, the work is only based on two points in time: post-surgery and post-testing evaluation. The quality and satisfaction information of patients and physicians in the study is pending.
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Drs. Majithia and Willey were joined by colleagues from 18 healthcare institutions and Prelude Dx on the paper, titled “The Clinical Utility of DCISionRT on Radiation Therapy Decision Making in Patients with Ductal Carcinoma In Situ Following Breast-Conserving Surgery,” published in the April issue of the journal Annals of Surgical Oncology. The study was funded by PreludeDx. The study was approved by the Western Institutional Review Board and by Institutional Review Boards from the participating centers. Patients in the study provided informed consent. The study was registered with ClinicalTrials.gov.