• Posted December 8, 2023

Women With Very Early Breast Cancer May Safely Skip Radiation Rx: Study

Some women with a very early form of breast cancer known as ductal carcinoma in situ (DCIS) can safely skip follow-up radiation therapy after surgery, new research suggests.

Results from a sophisticated genetic test are key to the decision to either undergo or skip radiotherapy, say researchers at Northwestern University in Chicago.

“Using [these] personalized diagnostic tools to predict the risk of recurrence or progression may prevent excessive treatment for some patients," said study lead author Dr. Seema Khan. She's a professor of surgery and cancer research at the university's Feinberg School of Medicine and Lurie Comprehensive Cancer Center.

The study results were presented Friday at the annual San Antonio Breast Cancer Symposium.

DCIS is a common breast malignancy. According to the American Cancer Society (ACS), with DCIS "cells that line the milk ducts of the breast have become cancer, but they have not spread into surrounding breast tissue."

Even though it's a "pre-invasive" cancer, DCIS is typically treated with surgery (either mastectomy or breast-conserving lumpectomy) because these cells can trigger more invasive disease elsewhere in the breast, the ACS explained.

Follow-up radiation treatments are often ordered after surgery, but as Khan noted in a meeting news release, "there is an increasing realization that DCIS carries an unnecessary treatment burden for many women."

Her team wanted to see if some patients might safely avoid radiation therapy.

The study included 171 women who underwent lumpectomy for their DCIS.

DCIS breast tissue from each patient was then subjected to the Oncotype DX Breast DCIS Score test in a lab. The test examines the expression of cancer-linked genes and generates a score ranging from 0 to 100. A higher score suggests higher odds that the cancer will return, the team explained.

Khan's team considered patients whose Oncotype test score was below 39 to be at relatively low risk for cancer recurrence, and these patients were eligible to skip follow-up radiotherapy.

Women who scored 39 and higher were recommended to get radiation treatments, per usual.

Almost all of patients (93%) followed the test-guided recommendations.

Tracking outcomes five years after each patient's surgery, the Northwestern team found rates of cancer were similar -- about 5% -- in the low-risk group who opted out of radiotherapy and the higher-risk group who did get radiation treatments.

In other words, skipping radiation didn't seem to raise risks for cancer recurrence among women whose tests allowed them to opt out of the treatment.

"Women who skipped radiation based on this score did not experience an excess risk of recurrence in the same breast during the five-year follow-up period,” Khan concluded. “These findings reveal a new approach to guide treatment decisions by determining which patients may benefit from radiotherapy and which patients may safely forego it.”

Because these findings were reported at a medical meeting, they should be considered preliminary until published in a peer-reviewed journal.

More information

Find out more about DCIS and its treatment at the American Cancer Society.

SOURCE: San Antonio Breast Cancer Symposium, new release, Dec. 8, 2023