Sharper Focus On The Breast

She was already worried, but as Betsy Lambert watched her surgeon consult the other women in the recovery room, she knew it was going to get worse. Two months earlier, the 48-year-old lawyer had noticed a hardness in one breast. A standard breast X-ray, or mammogram, showed no sign of trouble, but when the hardness persisted, she demanded a surgical biopsy. The surgeon was now telling Lambert's fellow patients their suspicious masses were benign. But when she got to Lambert, the last of six, she looked her in the eye and lowered her voice. "Can I see you in my office for a minute?" she asked. The biopsy, it turned out, had revealed something the X-ray had missed: a tumor nearly an inch in diameter.

Mammography can detect most tumors before they're even discernable by touch, enabling doctors to root them out quickly. Yet as Lambert's experience attests, the breast X-ray is still a maddeningly crude instrument. Eight out of 10 masses detected by mammography turn out to be false alarms, and the technique may miss as many as 9 percent of actual tumors. Radiologists are now racing to improve on that record. Their innovations are still years from general use, but two pioneering techniques-digital mammography and computer-enhanced MRI-could soon save many lives.

To produce a standard mammogram, a radiologist passes an X-ray beam through a woman's breast and records a black-and-white image on film. By taking annual pictures of each breast, and checking each picture against an earlier one, the radiologist can spot suspicious changes in the density and distribution of tissue. Unfortunately, even high-quality film captures only gross variations. If a woman's breasts are young and firm, or cluttered with natural fibrous masses, everything looks dense, and tumors become hard to spot.

Martin Yaffe, a physicist at the University of Toronto, has spent a decade trying to make breast X-rays more revealing-and he believes his new approach could do for mammograms what the compact disc has done for scratchy old LPs. The secret of X-ray imaging is that tissues of different densities absorb different amounts of radiation. To capture the subtle variations that don't show up on film, Yaffe electronically translates the X-ray image into digital computer code. Once the image is in that form, a computer can highlight tissue of any density, turning a tumor's subtle signature into a garish neon sign.

Digital X-ray is too new to have a clinical track record, but the technique has outperformed standard mammography in small lab tests. Yaffe plans to start a large clinical trial this year, and he predicts that the technique will be widely available by 1995. The new approach may never fully supplant conventional mammography; a digital X-ray machine costs roughly $200,000, a film-screen model just $80,000. That could conceivably double the price of a single test, yet Yaffe believes the technique would pay for itself by detecting tumors that are now being missed.

Even a digital X-ray machine. has its limits. Because X-rays don't penetrate silicone, they can't spot tumors growing near breast implants. Nor can they tell a benign cyst from a cancerous tumor. For those jobs, a handful of innovators are now using MRI (magnetic resonance imaging) and achieving good results. Unlike an X-ray machine, an MRI scanner uses magnetic fields and radio waves to determine the distinct chemical signatures of different tissue types. By programming the device to ignore fat, cysts and silicone, radiologist Steven Harms of Baylor University in Dallas can determine whether a breast mass is cancerous. No one proposes using such a costly tool for routine screening-except in women with silicone implants-but the procedure could replace many of the 500,000 biopsies now performed annually.

More important, it could help doctors analyze and treat known malignancies. When a woman develops a breast tumor, a physician's first task is to figure out how far it has spread. One of the greatest hazards is that a surgeon will remove the primary mass but pass over small colonies of cancer cells growing in other parts of the breast. In small trials, Harms's customized MRI has shown a sharp eye for these so-called multifocal cancers, far surpassing X-ray mammography. As for treatment, Harms believes his innovation could revolutionize the art of lumpectomy. When a surgeon carves a tumor from the breast, getting the whole thing often requires more than one operation. Harms reasons that if a lowpowered laser were aimed at the tumor while the MRI produced live images, a doctor could kill it in 10 minutes and send the patient on her way. For most women, these new techniques are still several years in the future. But for people like Betsy Lambert (who feels fine two years after having her missed tumor removed), the future can't come soon enough.

Standard mammography may detect harmless masses while missing malignant ones. But other techniques are in the works.

X-ray mammography is still the standard technique for breastcancer screening. It can detect most tumors before they're discernible by touch, but as many as 9 percent may go unrecognized.

Digital mammograms record X-ray images in computer code instead of placing them on film. With the right software, a radiologist can enhance subtle variations in an image, making tumors easier to spot.

Magnetic resonance imaging uses radio waves and magnetic fields to distinguish tumors from harmless masses in the breast. The big drawback--high-tech MRI pictures cost 10 times more than X-rays.