Breast cancer more likely to return if radiation is delayed

woman wearing a wrist watch

Delaying radiation therapy too long after breast cancer surgery significantly increases the risk of recurrent tumors in women treated for very early, or what is referred to as “Stage 0,” breast cancer, a new study warns.

Women were much more likely to experience a recurrence of DCIS or higher-stage cancer in the same breast if they received radiation therapy eight or more weeks after a lumpectomy or did not receive radiation therapy after surgery.

Stage 0 breast cancer—or ductal carcinoma in situ (DCIS)—is diagnosed based on the presence of abnormal cells in the milk ducts of the breast. Every year, more than 60,000 women in the United States are diagnosed with DCIS, and experts often debate how best to treat it because the abnormal cells don’t always develop into full-blown, or invasive, breast cancer. Standard therapies include lumpectomy, lumpectomy plus radiation, or total mastectomy.

“This study indicates not only that radiation therapy is an important component in the treatment of DCIS but also that it must be received in a timely manner,” says lead author Ying Liu, an instructor in surgery at the School of Medicine and a research member at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine.

[For Stage 0 breast cancer, ‘watch and wait’ may be best]

Delays in radiation therapy were more common among women who were black, unmarried, on Medicaid, diagnosed during the later years of the study, diagnosed with larger tumors, or whose cancer wasn’t entirely removed during surgery. “These groups, especially, may benefit from undergoing radiation therapy sooner,” Liu says.

Researchers studied data from 5,916 women in the Missouri Cancer Registry diagnosed with DCIS from 1996 to 2011 and treated with lumpectomy. Of those women, 1,053 (17.8 percent) received radiation therapy more than eight weeks after surgery, and 1,702 (28.8 percent) did not receive any radiation therapy as part of their initial treatment. The other 53.4 percent of the patients all received radiation without delay, within the eight-week time frame.

During the average six years of follow-up, 3.1 percent of women developed a recurrence of DCIS or an invasive tumor in the same breast. For women who received radiation within eight weeks, the rate of recurrence was 2.5 percent. After adjusting for age, race, pathological factors, surgical margin status and hormone therapy, the risk of breast cancer recurrence was 26 percent higher for women who had delayed radiation therapy and 35 percent higher for women who did not initially receive radiation.

“What we’ve found suggests the need for more studies,” Liu says. “Our hope is to provide clear-cut guidelines that will help more women reduce their risk of recurrence.”

Researchers presented their study at the American Association for Cancer Research (AACR) annual meeting in New Orleans. The Foundation for Barnes-Jewish Hospital and the Breast Cancer Research Foundation funded the work.

Source: Washington University in St. Louis

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