Medicine: Mammogram Muddle

More than 250,000 women 35 years old and older have taken part over the past three years in a breast-cancer detection program conducted by the American Cancer Society and the National Cancer Institute. Because any cancerous tumors they may have are detected early, say the sponsors, these women presumably will have a lower-than-average rate of mortality from breast cancer, which will kill some 32,000 in the U.S. this year. Last week the screening program became the center of a major medical storm stirred by a group of doctors who warned that X rays used in the screening might actually increase the risk of breast cancer.

Low Dose. Besides having her breasts examined manually and photographed by a heat-sensitive technique called thermography,* every participant in the screening program is annually subjected to mammography, or breast X rays. Although only an extremely low dose of radiation is required, a team of scientists under the leadership of Dr. Lester Breslow, a U.C.L.A. epidemiologist, nonetheless argues that it may well be enough to cause cancer. Mammography, Breslow insists, is "a striking example of a situation where the very disease may be caused by the technology."

As evidence, Breslow cited a seven-year breast-cancer detection program, involving 62,000 women, undertaken in the 1960s by New York's Health Insurance Plan (H.I.P.). Analysis of the H.I.P. statistics showed that while mammography was of significant value in women over 50, the screening program did not reduce the mortality rate in those under that age. Breslow also noted studies showing increased breast-cancer rates among women exposed to higher radiation levels—those subjected to X rays in treatment of tuberculosis, patients receiving radiotherapy for acute breast infection, and survivors of A-blasts in Japan. Extrapolating from these data, he concluded that "there is no absolutely safe dose" for X rays and urged prompt discontinuation of mammography in routine screening of women under 50.

To allay fears of women alerted by press accounts of Breslow's criticism, the National Cancer Institute (NCI) hastily called a meeting in Bethesda, Md., last week. The directors of the screening program noted that mammography techniques have improved considerably since the H.I.P. study began 12½ years ago and that the radiation doses now used have been reduced to about a third of their old level. More important, they said that about two-thirds of the cases detected were in an early, curable stage—and only about half these cancers could have been detected without X rays. Said Dr. Philip Strax, director of the New York detection center: "The real risk is in not doing mammography." Added Dr. Barbara Ward of Boise, Idaho: "These reports are doing more damage than good by scaring women away."