Using Ultrasound to Battle Cancer

Monday, October 30th 2000, 12:00 am
By: News On 6

WASHINGTON (AP) — Vicki Freeman lay perfectly still inside a tube-like machine as ultrasound waves beamed deep into her cancerous breast. Little bursts of heat signaled the beams were cooking her tumor to death — without a mark or cut to her skin.

Freeman is one of the first women to try a novel medical experiment to see if this ``focused ultrasound therapy'' might one day offer a noninvasive alternative to breast cancer surgery.

It will take years of study to prove whether cooking tumors works. But as women already clamor for less disfiguring breast surgery, pilot experiments at Houston's M.D. Anderson Cancer Center and Boston's Brigham & Women's Hospital signal the latest in a growing trend: research on ways to make cancer removal not just less invasive, but to quit cutting patients altogether.

``If you think about surgery, it's sort of medieval,'' says Dr. Darrell Smith, a Harvard University radiologist conducting Brigham & Women's study. ``We're trying to get more elegant in the way we do this. It's kind of Star Trek in a way.''

Yet it raises a serious safety question: Are doctors trying to make tumor removal too minimal, particularly for diseases like breast cancer where surgery can work very well? After all, scientists already know that some younger women undergoing lumpectomies get too little tissue cut out for cosmetic reasons, leaving them more vulnerable to cancer's return than if they had properly sized lumpectomies. Plus, if nonsurgical methods do prove safe, they'll require more complicated machinery — and thus will be more expensive — than a simple lumpectomy.

But some radiologists insist noninvasive technologies should eliminate just as much tumor as a surgeon's knife. A small Harvard study, to be unveiled at a radiology meeting next month, suggests focused ultrasound can successfully cook away benign breast tumors called fibroadenomas, bolstering hopes for the new cancer experiments.

And while breast cancer offers an easy-to-study target, the ultimate goal is to one day help harder-to-treat brain, liver or soft-tissue cancer, or other disorders like uterine fibroids, where surgery isn't optimal.

``We know from basic science and animal research that it can work. Now we have to show it's feasible,'' says M.D. Anderson's Dr. Marc Fenstermacher, who treated Freeman.

To do that, Fenstermacher and Smith will test 30 women destined for surgical removal of small breast tumors. Patients lie inside a specially outfitted MRI, or magnetic resonance imaging, machine. Guided by the MRI's continual sharp picture of the tumor, doctors position ultrasound focusing equipment called transducers, built into the MRI table, to beam into the tumor. On the MRI, the tumor lights up as 10-second blasts heat it to more than 140 degrees.

About a week later, study participants undergo a regular lumpectomy to see if the tumor really is dead and if enough tissue around it is free of cancer cells — an important safeguard for a first study. If it works safely, doctors eventually will seek Food and Drug Administration permission to test focused ultrasound without a lumpectomy.

``It meant I wasn't really benefitting myself ... but I hope I'm helping other women down the road,'' says Freeman, who praised the pain-free ultrasound.

How does it work? Hold a magnifying glass in sunlight. The lens can focus enough light to burn, say, a leaf directly underneath — but that's the only hot spot, Smith explains. Similarly, the transducers act like a lens to focus heat from high-intensity ultrasound waves just on the tumor, leaving other breast tissue unharmed.

Ultrasound kills not by burning but by altering cancer cells' proteins, much like boiling an egg stops a chick's development. It's not the only nonsurgical method under study, but it's completely noninvasive.

In contrast, the University of California, Los Angeles, is looking for volunteers to try freezing breast cancer using a needle-like probe stuck into the tumor, alternately freezing and thawing it until the cancer cells' membranes burst. Other scientists are experimenting with probes that deliver radiofrequency waves to burn liver or breast tumors, and with injectible drugs that sensitize certain tumors to cancer-killing light beams.

``The fundamental question: Which (method) gives us the best killing, best cosmetic result and most economical result?'' says UCLA's Dr. Helena Chang, who leads the freezing experiment.

If such methods ultimately do work, doctors caution they're only for tumor eradication — they won't replace the chemotherapy and radiation many patients need after a tumor is removed.

For more information on focused ultrasound clinical trials, call 1-800-392-1611, ext. 3. For information on cryotherapy trials, call 1-888-798-0719.