Surgeons in the Washington area and at major medical centers across the country have all but abandoned the radical mastectomy in the treatment of breast cancer.

The operation, involving the removal not only of the breast but the lymph nodes and underlying muscles down to the ribs was performed on millions of American women in the last 70 years by doctors who thought it would improve their patients' chances of survival. But large-scale scientific tests conducted in recent years have shown the radical procedure to be unnecessary in most cases.

There are preliminary findings that, if borne out by time and further testing, could make removal of a woman's cancerous breast obsolete.

A procedure known as total mastectomy, taking just the breast without the chest muscles, has become standard treatment for most patients. And there is mounting evidence that less mutilating surgery -- even radiation therapy with preservation of almost the entire breast -- may be just as effective.

"Conceptions from the past blind us to facts which almost slap us in the face," said Dr. W. A. Halsted, who invented the radical mastectomy at the turn of the century. It is ironic that his concept of how cancer spread was used for three quarters of a century to justify the radical surgery and until recently stood in the way of adoption of new surgical methods.

Harvard Medical School radiation therapists who simply remove the cancerous lump from the breast and treat the rest of the breast with radiation are achieving results that so far -- at least five and in some cases 10 years after treatment -- are as good as those for breast removal. Other researchers are beginning nationwide tests on women with cancer to compare partial breast removal with or without radiation therapy to the now-standard removal of the whole breast.

The new approaches are being tried because surgeons and cancer specialists have rejected Halsted's theory that breast tumors always spread first to the muscles and lymph nodes nearest the breast.

They now accept the view that early cancer spread can occur when single malignant cells travel through the bloodstream to other parts of the body. That leads to the conclusion now commonly held by researchers that controlling breast cancer depends on killing these wandering cells with drugs or changing the body's hormone balance to enable it to fight the disease itself.

As favorable reports of less drastic treatments mount, doctors are becoming more open to offering patients who have lost a breast to cancer the opportunity for reconstruction of the breast using plastic surgery. One specialist estimates that 10,000 women a year undergo surgical reconstruction after masectomy.

In June, a panel of experts summoned by the National Institutes of Health to try to reach a consensus on how to treat breast cancer recommended that the total mastectomy be adopted as the standard operation for the majority of patients, those with early signs of disease. The terms "total" and "modified radical" are used interchangeably to mean removal of the breast and lymph nodes only.

The panel cited the studies showing that removal of the underlying muscles offered no better chance of survival than taking the breast alone. The experts took note of early but encouraging results obtained in Italy with partial mastectomy -- the removal of only the tumor and a section of the breast around it. However, they didn't recommend that the procedure be adopted at this time.

Surgeons contacted at hospitals throughout the Washington area appear to have adopted the NIH recommendation. Radical mastectomies, they said, have become a rarity, done only on the occasional patient whose cancer has visibly spread to the muscles underlying the breast. A few surgeons here are even doing partial mastectomies on patients with very small tumors.

At the National Cancer Institute in Bethesda, specialists are seeking patients willing to participate in experiments comparing the effectiveness of radiation therapy to removal of the breast.

A series of radiation treatments already has been used in lieu of mastectomy to treat 176 patients with early breast cancer in Boston, and so far the same number of patients has remained cancer-free, as would be expected following total breast removal. The breast does look different after exposure to high doses of radiation, but Dr. Samuel Hellman, chief of Harvard's radiation therapy department, called the cosmetic results "quite good" in at least three-quarters of the patients. Hellman pioneered the radiation treatment 11 years ago, initially as an alternative for patients too ill to undergo surgery.

Only 6 percent of the patients Hellman treated five or more years ago have had a recurrence of their cancer. That is the same recurrence rate one would expect after surgery. Hellman said this argues that radiation is as good as surgery for preventing the spread of breast cancer to surrounding tissue.

The long-term survival of patients depends on how many develop cancer in the liver, lungs, brain and elsewhere. Since breast cancer can recur up to 30 years after treatment, it will be years before the final success of radiation therapy is known.

In Hellman's procedure, each patient has a "lumpectomy" -- taking the tumor and a minimum of surrounding breast tissue -- and removal of some lymph nodes from the armpit to determine whether the cancer has spread there. She then has daily X-rays or cobalt treatments of the entire breast at a clinic for five weeks. Finally, she is hospitalized, and a small radioactive implant is put into the breast at the tumor site for two or three days.

The treatments cause temporary sunburn-like blistering, but the final appearance of the breast in most patients is not unattractive, Hellman said. About one-quarter have more extensive scarring. There have been a few complications, including radiation-induced rib fractures, short-term lung inflammation and, in one patient, scarring of the sac around the heart after radiation treatment of both breasts.

Some experts have expressed concern that the radiation may increase the risk of developing another tumor years after treatment. But Hellman contends this fear has not been borne out in Hodgkins' disease patients treated with similar radiation doses. However, it takes years for radiation-induced cancer to show up, and no one knows what the long-term risk of radiation therapy for breast cancer patients will be.

The reluctance of cancer surgeons to remove less than the whole breast stems from a factor called multicentricity -- that is, when a breast is removed for one tumor, pathologists often find microscopic cancers elsewhere in the breast. Since it is also known that women who have had one breast cancer are at a higher risk of developing a second one, many surgeons argue that the entire breast should be taken.

The importance of multicentricity is a matter of intense debate.

Dr. Bernard Fisher, the University o Pittsburgh surgeon who directed the studies that discredited radical mastectomy, plans a similar experiment comparing total and partial breast removal, with and without subsequent radiation treatments. He said a trial of partial mastectomy is justified because of the number of women who actually become ill with two separate breast cancers is far lower than would be predicted from the number of multicentric tumors seen by pathologists. It has been suggested that many of these microscopic second cancers are slow-growing and would never cause disease.

If this is the case, the patients in Fisher's trial who receive only partial mastectomies without breast radiation should do as well as those who get more extensive treatment. But opponents of this view cite a study more than 20 years ago in which 10 patients given lumpectomies had a high rate of recurring breast cancer.

With the focus of treatment shifting toward prevention of cancer spreading through the bloodstream, doctors are turning to the early use of chemotherapy -- giving anticancer drugs to patients for several months after surgery in hopes of poisoning any remaining cancer cells.

In 1976, Dr. Gianni Bonnadonna of Milan published preliminary results of three-drug therapy given right after surgery to patients with breast cancer that had reached the lymph nodes. Although now, four years after treatment, the number of Bonnadonna's patients who remain free of cancer has decreased, 90% of the younger breast cancer patients who received chemotherapy are still alive, compared to only 71% of those who did not. Patients who contracted breast cancer after menopause did not appear to benefit from the drugs.

On the basis of these findings and Fisher's confirmation of them, the practice of giving chemotherapy to younger patients with cancer that has reached the lymph nodes has been widely adopted, according to physicians interviewed.

As with Hellman's radiation treatments, long-range risk of the drugs -- drugs -- which damage normal cells as well as cancer cells and may themselves cause cancer -- will take years to determine. But researchers are heartened by signs that early chemotherapy may improve a patient's chances of surviving breast cancer, and Dr. Jane E. Henney of the National Cancer Institute said the drugs now should be tested on patients with no apparent spread of their cancer.

"If you're a pessimist you can say, 'Oh with time it (the benefit of chemotherapy) will all go away, '" she said. "But it means we're getting somewhere, finally, with this disease."

Henney also said the hormone responsiveness of each tumor may turn out to be the factor doctors should use to decide whether to treat a patient by giving chemotherapy or by changing her hormone balance. Between 50 and 60 percent of breast cancers contain what are called receptors for the hormone estrogen, and in these cases the estrogen normally secreted by the body appears to encourage tumor growth. Many such tumors can be treated with some success by lowering the patient's natural supply of estrogen, either by removing the ovaries that produce the hormone or by using an antiestrogen drug.

Tumors without estrogen receptors are unaffected by the hormone supply, but some research suggests they, may be more sensitive to chemotherapy. Fisher is now directing a trial that compares and combines the two approaches. f

Thousands of women who have had breasts removed are now looking into surgery that can rebuild their lost breasts. No national figures are available, but Dr. Reuven K. Snyderman, head of plactic surgery at Rutgers Medical School, estimates that 20 percent of the 90,000 women who have mastectomies each year see a plastic surgeon about reconstruction, and about 12 percent -- about 10,000 women a year -- actually go through with it.

After removal of a breast, a woman is left with a flat expanse of skin over-lying the muscles. Patients who have had mastectomies usually wear form-fitted cushions inside their bras to match their other breast. To reconstruct a breast, plastic surgeons may insert a silicone mound under the skin, sometimes reducing and elevating the remaining breast to make the two sides match. They also can create an artificial nipple on the skin over the implant, either taking skin from the remaining nipple or using dark skin from the inner thigh.

Sometimes the cancer surgeon who removes a breast is willing to save the original nipple by grafting it to the upper thigh, where it stays until it can be returned to the skin over the implant.

Snyderman said he informs each patient considering reconstruction that the goal is to make her look normal in a bra or a bikini, not to achieve a "triumph in the nude." He has found that reconstruction is best approached six months or more after mastectomy, when a woman has grown accustomed to loss of her breast and the skin on the chest has softened.

He said he shows patients photographs, introduces them to other patients who have had the plastic surgery and urges them to bring husbands or boyfriends to see him.

Opponents of breast reconstrution have claimed that it is risky for the patient. If a tumor recurs behind a silicone implant, it may be impossible to detect by physical examination, they say. And some surgeons refuse to transplant a nipple from a cancerous breast because the risk that it may harbor malignant cells.

Snyderman insists there are safeguards and that "we in no way jeopardize the survival of a woman by reconstruction."

Although experts argue for hours about which of the available therapies is best, some physicians offer specific advice to women with newly diagnosed breast cancer. Dr. Daniel Hoth, a Georgetown specialist, suggested that a woman get two or three doctors' opinions, if possible, before making a decision.

Fisher favors two-stage surgery in which a sample of the suspicious lump is first taken and examined by a pathologist. The patient then may discuss the findings and alternatives with her doctor before deciding what to do. A once common approach was to test the tumor while the woman is under anesthesia and remove the breast if the tumor proves malignant.

Henney recommended that every patient make sure her tumor is tested for estrogen receptors at the time of surgery because knowing the results of such a test may be vital in treatment decisions years later. If a hospital does not do receptor determinations, a tissue sample can be sent elsewhere.

Once a woman has investigated the alternatives, she must decide with her doctor whether to have the standard total mastectomy, one of the newer treatments or whether to enter a trial designed to compare newer therapies against established ones.

Fisher's National Surgical Adjuvant Breast Project, the National Cancer Institute and other researchers are seeking patients. But to enter most trials a patient must agree to be assigned one of the treatments under study, rather than choosing one herself because the reliability of such tests depends on random selection of each group.

Fisher advocated selection of either a well-established therapy such as total mastectomy or volunteering for a carefully controlled trial designed to test the merits of less-established approaches. Partial mastectomies and radiation therapy are alternatives whose final results are unknown, he said, and they should not yet be used except as part of an organized study in which records and statistics are carefuly collected and monitored.

"In God we trust," he said. "All others have data."