Treatment for Localized Breast Cancer Varies Widely
Finding underscores need for consensus on therapies
WEDNESDAY, March 17, 2004 (HealthDayNews) -- Treatment of the localized breast cancer called ductal carcinoma in situ (DCIS) varies widely across the United States, a new study finds.
What this means, the study authors say, is that some women may be getting treatment that's too aggressive, while others may be getting treatment that's not aggressive enough.
"This is a disease where there is a lot of [treatment] controversy," says Dr. Nancy Baxter, an assistant professor of surgery at the University of Minnesota School of Medicine. She's also the lead author of the new study, which appears in the March 17 issue of the Journal of the National Cancer Institute.
"So it is not surprising to see the variation," Baxter adds.
What is surprising, she says, is the relatively low rate of radiation therapy that women receive. Even with a somewhat aggressive form of DCIS, "a third of [patients] did not get radiation," she says. "Most people would say they should have."
DCIS is the most common form of noninvasive breast cancer. It is confined to the milk ducts; it has not spread through the walls of the ducts into the fatty tissue of the breast. Nearly all women with cancer at this stage can be cured, and the best way to find DCIS early is with a mammogram, according to the American Cancer Society.
For the new study, Baxter and her co-researchers used a database from the National Cancer Institute to assess the treatment of more than 25,000 women with DCIS who had been diagnosed from Jan. 1, 1992, through Dec. 31, 1999. They evaluated rates of mastectomy, breast reconstruction, radiation therapy after lumpectomy, and dissection of the auxiliary nodes.
While DCIS accounts for a small percent of all breast cancers, the number of cases has been increasing in recent years. This is partly due to improvement in mammography, which, in turn, has detected more cancers at earlier stages, Baxter says.
About 55,700 DCIS cases were diagnosed in 2003, the American Cancer Society says. Treatment options include mastectomy, lumpectomy, lumpectomy with radiation, and dissection of the auxiliary nodes.
Baxter's team found the rate of mastectomy decreased from 43 percent in 1992 to 28 percent in 1999, even after controlling for such factors as age, geographic location and tumor size.
Almost half of those undergoing lumpectomy did not receive radiation therapy. And 33 percent of those with the most aggressive type of DCIS did not have radiation therapy, the study found.
Women were less likely to undergo dissection of the auxiliary nodes over the time period studied. In 1992, 34 percent had it performed, but just 15 percent did in 1999.
The type of treatment recommended varied greatly, the researchers found, and also differed depending on geographic region. For instance, 69 percent of patients in San Francisco had breast-conserving therapy, but only 39 percent were prescribed radiation therapy afterward. But in Hawaii, 67 percent of patients were given breast-conserving therapy and 74 percent got radiation therapy afterward.
The variation is partly due to physician advice and also patient preference, Baxter says. "Some women are getting aggressive treatment, perhaps more than they need, and some are getting treatment that is not aggressive enough. Experts should come to a consensus."
But another breast cancer expert, Dr. Monica Morrow, who wrote an editorial to accompany the study, says part of the variation is inherent "because the term DCIS encompasses a whole lot of things. It might be [a tumor] the size of a pin in a 75-year-old or fill three-quarters of the breast of a 35-year-old."
"Some variation is physician-driven and some patient-driven," adds Morrow, a professor of surgery at Northwestern University.
And, Morrow says, regardless of whether a woman chooses a mastectomy or the minimal treatment of lumpectomy, the risk of dying is similarly low.
Baxter agrees. "Women with DCIS, we know they have an excellent prognosis. Ultimately, over 10 years, only 2 percent will die from breast cancer."
Until more data are gathered on DCIS, Baxter and Morrow agree that women diagnosed with this localized breast cancer should be aware of the wide variation in treatment options and get a second opinion.
Meanwhile, another new study has found some predictors of survival in breast cancer patients. In an 11-year review of patients who had tumors removed but no evidence of cancer in their lymph nodes, Wake Forest University Baptist Medical Center researchers found certain factors predicted cancer recurrence.
Among the factors were larger tumor size and a higher concentration of an enzyme that allows for tumor spread. The study appears in the April issue of Clinical Cytometry.