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New Screening Catches More Breast Cancers

WEDNESDAY Sept. 3, 2008 -- While tremendous progress in screening and treatment for breast cancer has been made in recent years, some 184,000 new cases of breast cancer will be diagnosed in the United States in 2008, and about 41,000 women will die of the disease.

Researchers are now focusing their efforts on reducing these numbers even further.

Four studies being presented this week at the American Society of Clinical Oncology's 2008 Breast Cancer Symposium in Washington, D.C., highlight both areas of progress and areas that need extra emphasis.

A screening technique known as molecular breast imaging (MBI) detected three times as many breast cancers in women who have dense breasts and who are at a higher risk of developing the disease. These findings suggest that MBI could one day be added to conventional mammography.

Using an injected radiotracer (provided, for this study, by Bristol-Myers Squibb), MBI is able to detect differences in the behavior of cancer tissue as compared to normal tissue.

In this study, MBI detected 10 of 13 cancers among 375 patients completing a 15-month follow-up period. Mammography, by contrast, detected three of 13 cancers.

"If we had had a combination of both techniques, we would have detected 11 of 13 cancers," said study author Carrie B. Hruska, a research fellow in the department of radiology at the Mayo Clinic in Rochester, Minn. "MBI detected more cancers than screening mammography but didn't produce more false positive results."

Hruska spoke at a Wednesday teleconference with authors of the three other studies.

Also, the number of biopsies that actually resulted in cancer was much higher with MBI (28 percent) than with mammography (18 percent).

"Based on the results, MBI has shown great promise as a valuable adjunct to screening mammography in women with dense breasts and who are at an increased risk of developing cancer," Hruska said.

But while relatively inexpensive and easy to use, MBI is not yet widely available.

"This is an area that is very important, and where we really need to do further work," said Dr. Eric Winer, moderator of the teleconference and director of the breast oncology center at Dana-Farber Cancer Institute in Boston.

A second study, conducted by researchers at Johns Hopkins University, debunks the long-held notion that women in rural areas are more likely to chose mastectomy over lumpectomy because of difficulty traveling to radiation facilities.

Radiation is considered standard-of-care for women after they have received a breast-conserving lumpectomy, although not for women who undergo a mastectomy.

There were no notable differences between radiation rates following lumpectomy for women in rural areas as compared with women in urban areas, although the study did confirm that more women in rural areas (59.9 percent) opted for mastectomy, versus 44.9 percent of women in urban areas.

"The disparity . . . is not necessarily due to the availability of radiation therapy but to other factors," said study author Dr. Lisa K. Jacobs, an assistant professor of surgery at Johns Hopkins University in Baltimore.

"This would seem to suggest that if a woman in a rural area chooses to have a lumpectomy, she will most likely not fall through the cracks in terms of getting radiation, which is somewhat reassuring," Winer said. "But it would be interesting to look at this further."

In a third study, researchers at M.D. Anderson Cancer Center in Houston found that older black women undergoing lumpectomy for early-stage invasive breast cancer were less likely to receive recommended post-surgery radiation therapy than their white counterparts.

Only 65 percent of black women received radiation, compared with 74 percent of white women. "The difference is concerning, given that radiation after lumpectomy is generally considered standard therapy," said study author Dr. Grace Smith, a postdoctoral fellow in the department of radiation oncology at Anderson.

Disparities also existed in the younger range (women aged 65 to 70) of this older group, who were less likely to have medical conditions precluding radiation therapy. Here, 71 percent of black women received potentially lifesaving radiation versus 81 percent of white women.

The largest disparities were evident in the East South Central region of the United States, the Pacific West and New England.

"What seems to be happening is that the use of conservative surgery and radiation opens the door for disparities to play a greater role in limiting access to care," Winer said. In this two-step process (surgery plus radiation), Winer added, "it is possible for women to fall through the cracks."

The final study addressed women with HER2-positive breast cancer, which traditionally has a worse prognosis than other forms of breast cancer.

Chemotherapy and treatment with Herceptin (trastuzumab) before surgery results in a "pathologic complete response," meaning no evidence of invasive disease in the breast or lymph nodes existed in many patients.

Patients who did not have this complete response were three times more likely to have a recurrence, the researchers from M.D. Anderson reported.

In about one-third of those not achieving a complete response, the cancer had converted from HER2-positive disease to HER2-negative disease, meaning it was no longer responsive and had possibly become resistant to HER2-specific therapies such as Herceptin.

The authors stressed the importance of reassessing tissue for HER2 status after preoperative treatment.

More information

Visit the National Cancer Institute for more on breast cancer.

Posted: September 2008


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