• Posted March 31, 2026

'Watch and Wait' Approach Safe For Women With Precancerous Breast Condition, Trial Finds

A “watch and wait” approach might be best for women with a precancerous breast condition, a new clinical trial has found.

Women with low-risk ductal carcinoma in situ (DCIS) had about the same rates of invasive cancer if they were put on active surveillance compared to those immediately treated with surgery, researchers recently reported at the European Breast Cancer Conference in Barcelona, Spain.

“For women with low-risk DCIS, these interim results are reassuring,” researcher Dr. Jelle Wesseling, a group leader with The Netherlands Cancer Institute in Amsterdam, said in a news release. “There is currently no indication that active surveillance leads to worse early outcomes compared with immediate surgery.” 

He added that it’s important to explain that active surveillance doesn’t mean withholding treatment.

“It does mean that patients are closely monitored and that surgery remains possible at any time,” Wesseling said.

Active surveillance is already considered a treatment option for other low-risk cancers, most notably prostate cancer.

Women with DCIS have abnormal cells inside the milk ducts of their breast, researchers said in background notes.

It’s not cancer, but it’s considered precancerous because the cells might spread to other parts of the breast or body, according to the National Cancer Institute.

DCIS is typically treated with surgery and sometimes, with other treatments like radiation or hormone therapy, researchers said.

However, research suggests that 4 out of 5 DCIS cases will never become invasive or life-threatening, researchers said.

“For decades, DCIS was framed as ‘early-stage breast cancer.’ As a result, it has almost always been treated in the same way as breast cancer,” Wesseling said. “But if most DCIS will never become dangerous, an important question arises: Are some women receiving more treatment than they need?”

For the new trial, researchers recruited more than 1,400 women with low-risk DCIS treated at about 60 hospitals in The Netherlands.

When the trial started in 2017, the first 73 patients were randomly assigned to either surgery or active surveillance.

After that, patients were allowed to choose between the two options. About three-quarters opted for active surveillance.

In all, 9% of the surgery group has since wound up with invasive cancer, the study found, compared with 6% of those in the active surveillance group.

Tumors in patients with active surveillance were slightly larger on average when detected – 6 mm compared to 9 mm – but were not more aggressive, researchers found.

These results indicate that DCIS might be overtreated if patients and doctors immediately opt for surgery, but Wesseling said longer follow-up and more research will be needed before any changes can be made to breast cancer guidelines.

“As a doctor, I am guided by the principle ‘first, do no harm,’ ” Wesseling said. “The goal is to avoid unnecessary treatment without putting women at risk.”

The meeting’s chair, Dr. Isabel Rubio, head of breast surgical oncology at the University of Navarra Clinic in Madrid, agreed with Wesseling.

“DCIS is a common condition that is often picked up through breast screening. Although many women with DCIS will not develop invasive cancer, surgery is currently the standard treatment for most patients,” she said in a news release.

“With longer follow-up, these findings may help support a more de-escalated approach to care for selected patients, suggesting that carefully monitored active surveillance could offer outcomes similar to surgery, while avoiding overtreatment,” Rubio said.

Wesseling presented these findings Friday at the meeting. Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

The National Cancer Institute has more on ductal carcinoma in situ and active surveillance.

SOURCE: European Breast Cancer Conference, news release, March 27, 2026