Science & Technology: MEDICINE
X-RAYS UNDER FIRE
From the library in his striking home in San Francisco's Haight-Ashbury district, Dr. John W. Gofman picks up Nuclear Milestones, a book that speaks to the great irony of his life's work. In it, Gofman, professor emeritus of molecular and cell biology at the University of California at Berkeley, is pictured with former Atomic Energy Commission chief Glenn T. Seaborg. In Seaborg's lab, Gofman did pivotal research on plutonium in the 1940s, speeding A-bomb development.
Today, Gofman, 77, is better known as a controversial physician and scientist who has spent much of his career agitating about the dangers of radioactive fallout. Now he is dropping a bomb of his own: Based on a review of 50 years of medical literature beginning in the 1920s, Gofman claims that up to 75% of all breast cancers seen today may have been caused by the ionizing radiation from medical X-rays.
VAST OVERSTATEMENT? If Gofman is right, the message is heartbreaking: Some 182,000 American women will be diagnosed with invasive breast cancer in 1995, predicts the American Cancer Society, and about 46,000 will die of it. At least some of those cases might have been prevented. Gofman's argument, however, is that since medicine has subsequently taken steps to limit patient exposure to this radiation, those rates should be peaking over the next decade or two.
Gofman's critics say he has vastly overstated the incidence of X-ray-induced breast cancer. He made the determination from calculating average population exposures in prior decades, with risk factors determined by studies of women with known high-dose radiation exposure. Indeed, the levels of X-ray exposure for women decades ago often were many times greater than current levels. Patients undergoing certain therapeutic X-ray treatments 50 years ago, for example, routinely got 400 "radiation absorbed dose" units, or RADs, vs. 15 millirads (one-thousandth of a RAD) common for diagnostic chest X-rays today.
Because of the limits of historical analysis, medical record-keeping, and the complexity of cancer, it could take years to determine exactly what the impact of radiation has been. For now, the biggest concern among Gofman's critics is that his pronouncements could spread new fears about breast X-rays.
CONSTANT GLARE. Gofman says his findings have nothing to do with today's mammograms. He notes that typical exposure is now less than one-third of a RAD, or just one-hundredth as much radiation as in the 1960s. Most doctors believe that for middle-aged and older women in particular, the benefits vastly outweigh the risks. "The worst possible outcome of Gofman's study," says Dr. Fred A. Mettler, chairman of radiology at the University of New Mexico School of Medicine, "would be for women to stop having mammograms."
No one, however, disputes that ionizing radiation can be hazardous, and the breast seems to be especially vulnerable. Of 41,000 people who survived extreme exposure during the Hiroshima and Nagasaki atom bomb blasts, 295 developed breast cancer--about 50% more than normal for Japan. Higher-than-normal incidence is also found in women who have undergone X-ray fluoroscopy--once part of tuberculosis therapy. Instead of taking a split-second film, doctors observe the patient under a continuous X-ray glare. Doses have come down today. But Gofman still worries that doctors, especially overseas, are not taking enough care to minimize fluoroscopy exposure.
Critics complain that Gofman hasn't published his findings in a respected journal that is subject to peer review. Instead, he wrote a book: Preventing Breast Cancer: The Story of a Major, Proven, Preventable Cause of This Disease, just published by the San Francisco-based Committee for Nuclear Responsibility Inc.
Even before viewing the data, some experts cringe at the apparent hyperbole. "That 75% figure is ludicrous," says Mettler, who is also the U.S. delegate to the U.N. Scientific Committee on the Effects of Radiation. He points out that Hawaii has the highest incidence of breast cancer in the U.S., though X-rays were rare.
Other researchers believe dietary fat, hormone levels, and genetic disposition for cancer rates play a much bigger role than past X-ray exposures. Gofman's antiradiation bias, says Mortimer M. Elkind, a Colorado State University radiologist, means he "tends to see a skeleton behind every curtain."
Yet Gofman surely has found some frightening skeletons. The list of uses and abuses for "the ray," as scientists called it, is long and bizarre. Discovered 100 years ago, this invisible, short wavelength radiation was first used for imaging. Then doctors found that some patients they exposed actually improved, leading to treatments for pneumonia and bronchitis. X-rays were also used to treat post-partum mastitis, an inflammation of a nursing woman's breast. Doctors "didn't realize cancer was a disease that comes 10 or even 60 years after the radiation insult," says Gofman.
In the 1920s, beauty parlor operators sometimes wielded X-ray machines to zap clients' unwanted facial hair. In the 1930s and 1940s, "shoe fitters" arrived at department stores. Customers shoved their feet into these fluoroscopic contraptions, which showed the bones of the feet in motion. Until the 1960s, dermatologists routinely used X-rays to zap 80 different skin maladies--from acne to warts.
By the 1950s, some scientists were sounding the alarm. One of their first targets was the faddish use of fluoroscopy during "well baby" visits, in which pediatricians would hold the button down while mothers watched their healthy babies' organs in real time. Some babies underwent the procedure once a month for two years, subjecting them to at least half a dozen RADs over this period. Gofman says that may explain relatively low breast cancer rates in poor, rural communities, where X-rays were rarely used.
Gofman expects his hypercritical colleagues to take a fine-tooth comb to his data. Radiologists in particular are "afraid to admit the mistake anybody could have made," he says wearily. In his book, he repeatedly points out that doctors' use of X-rays was based on the best knowledge available at the time.
WREAKING HAVOC. Even so, the steady reduction of RAD levels in recent years reflects general awareness of the dangers. And continued vigilance is essential, say Gofman's supporters. Without endorsing Gofman's numbers, William E. Morton, professor of environmental medicine at Oregon Health Sciences University School of Medicine says that Gofman has "done a service by pointing out the reality of the risk" of X-rays.
Gofman may have overstated those risks. But there is a lesson in his cautions. With public attention increasingly focused on the role of genetics in cancer, and with the recent discovery of the BRCA-1 breast cancer gene, environmental factors are getting less attention. However, "environmental and genetic impacts go hand in hand," says Mark Skolnick, vice-president of research at Myriad Genetics in Utah. The very notion of a gene predisposing a woman to cancer means some other event such as diet--or radiation--must trigger it. Even if Gofman's numbers are off, he has highlighted the havoc well-meaning technology can wreak when pushed too far.
...BECAUSE OF PAST ABUSES OF X-RAYS?
-- Medical X-rays, though overused prior to 1970, caused little harm
-- Spread over a long lifetime, low-dose radiation is safe
-- The causes of breast cancer are not known
-- Atom bomb studies show high-dose radiation can cause breast cancer
-- Continuous "fluoroscopy" was particularly risky
-- Breast cancer may be largely preventable By Joan O'C. Hamilton in San Francisco, with Neil Gross in New York