Radiologists Cite Studies to Support Regular Mammography Screening of Women Under 50

CHICAGO--A pair of large-scale clinical investigations reportedat the annual meeting of the Radiological Society of North Americais renewing the controversy over the need to perform mammographyin young women.

Data from the Screening Mammography Program of British Columbia(SMPBC) indicated that 15% of the cancers detected in 150,147asymptomatic women who had a mammographic examination in a 5-yearperiod were in women under age 50. Mammography detected cancerin an early, curable stage in approximately 87% of these women,and even found cancer in dense breast tissue.

"It usually is more difficult to detect cancer in dense tissuethan fatty tissue. However, we had increased cancer detectionrates in young women with dense tissue because many of the cancersshowed up as calcium deposits," said Linda Warren Burhenne,MD, executive director of the SMPBC, the largest mammographicscreening program in North America.

28% of Cases Under Age 50

A 3-year study of 3,159 women who had breast biopsies at ThomasJefferson University Hospital, Philadelphia, found that 28% of851 women with breast cancer were under age 50, and 46% of thetumors detected in the younger women were nonpalpable.

"Breast cancer tumors that are smaller, nonpalpable, andless aggressive histologically have better prognosis," saidEmily Conant, MD, assistant professor of radiology, Thomas JeffersonUniversity Hospital.

Based on the data from their studies, Drs. Warren Burhenne andConant both advocate regular mass mammographic screening of youngwomen. Although the incidence of breast cancer in British Columbiais higher than that in any of the other Canadian provinces, mortalityfrom breast cancer is the lowest. "We believe this is occurringbecause nearly 40% of all the eligible women in British Columbiaare having annual mammograms," Dr. Warren Burhenne said.

"If women [in the Pennsylvania study] had not had mammogramswhen they did, early cancers that are too small to be felt onphysical examination would not have been detected," Dr. Conantpointed out. She and her colleagues at Thomas Jefferson Universityconsequently advocate annual mammograms in the 40- to 49-year-oldage group.

Stephen A. Feig, MD, director of breast imaging and professorof radiology, Thomas Jefferson University Hospital, noted thatcombined data from other recent clinical trials involving youngwomen in the United States and Europe show that routine mammographycan reduce mortality from breast cancer by 18%.

For that reason, Dr. Feig chastised the National Cancer Institutefor failing to recommend mammographic screening of young women.

In 1993, the NCI chose not to urge mammography for women in the40- to 49-year age group because no randomized, controlled investigationsprovided clear evidence that regular mammography reduced mortality.

A statement released by Daniel B. Kopans, MD, director of breastimaging, Massachusetts General Hospital, and associate professorof radiology, Harvard Medical School, emphasized that none ofthe clinical trials of breast cancer have been designed for orconducted on women in the 40- to 49-year-old age group.

"In order to be able to 'prove' the expected mortality reductionof 25% to 30% among women ages 40 to 49, with 'statistical significance,'a randomized, controlled trial would have to include almost 500,000women in this age group. All of the world's trials put togetherhave involved fewer than 170,000 women in this age group,"Dr. Kopans wrote.

"The 'perfect' trial therefore," Dr. Feig said, "wouldtake 15 years, and in the meantime, thousands of women will die."Statistics show that one of every four deaths from breast canceroccurs in women younger than age 49. In addition, 40% of all theyears of life lost because of breast cancer involve women youngerthan age 50, Dr. Feig said.

Mammographic screening of older women every 2 years has increasedthe rate at which breast cancer is detected in its early stages,and it has reduced the number of deaths from breast cancer. "Screeningyounger women every year should have an equal effect," Dr.Feig commented.

Added Dr. Warren Burhenne, "There is no authority in theworld that would disagree that early detection of breast cancerleads to better outcomes."