In August 1984, Tobey Schriftman found a lump in her left breast. It wasn't the first time. The 34-year-old Cheltenham, Pa., woman had developed benign breast cysts before, but they had always disappeared by the time of her next menstrual cycle.

But this lump, she told her husband, felt different. She promptly went to her gynecologist, who ordered a mammogram and then referred her to Philadelphia surgeon Venerando Jaurigue.

Jaurigue examined Schriftman on Aug. 17, 1984, and noticed what he described as "an area of thickening" in her left breast. He told Schriftman this was another example of benign fibrocystic disease -- his conclusion after he looked at the mammogram report, which raised the possibility that extensive cysts might be obscuring a growth in her breast.

When Schriftman saw him in November, she recalled later, she complained that the lump was now visible and had altered the shape of her breast. Jaurigue concluded from his exam that there were no changes and that Schriftman continued to suffer from benign cysts. Because of her medical history and because the thickened area appeared stable to him, he did not order a biopsy.

In December 1984, routine blood tests ordered by a family doctor found that she had an abnormal liver function. By March 1985, Schriftman had the bad news: The lump in her breast was cancer, and it was spreading relentlessly into her liver, her ovaries and her bones.

On April 19, 1989, Tobey Schriftman, mother of two, died at age 38.

But before she died, Schriftman sued, joining the growing ranks of women who have made breast-cancer misdiagnosis one of the most active and costly areas of medical malpractice. Schriftman settled her case against the doctor for $675,000.

Physicians, lawyers and insurance groups report the same trend: Women are increasingly blaming doctors for failing to find breast cancer and are seeking redress in the courts.

Most often, plaintiffs' attorneys say, women are suing because they discover a cancerous breast lump themselves, as Schriftman did, only to be told by doctors that it is nothing to worry about.

They also are suing over mammograms or radiologists' interpretations that falsely report a malignant breast is all right and over "needle aspirations" of suspicious lumps that fail to detect deadly cancerous cells lurking inside.

Frequently, the lawsuits are pressed by surviving husbands, children and parents years after the women themselves have died -- as in the case of Willingboro, N.J., resident Terri Barber, whose family was awarded $850,000 by a jury in 1988, three years after her death at age 27.

Unfortunately for the woman plaintiff, says Philadelphia medical malpractice lawyer James Beasley, it is her death from breast cancer that "establishes the case; she wins her argument."

In May, the American College of Obstetricians and Gynecologists reported that a 1987 survey of its membership showed that more than 70 percent of all "failure to diagnose cancer" cases against its members now stemmed from breast cancer misdiagnoses, a finding that is expected to be repeated in a new survey.

Because of what it termed a "sufficiently severe" breast-cancer lawsuit threat, the group offered a special seminar called "Risk Management Strategies in Breast Cancer Diagnosis" to doctors attending the organization's national convention last May in San Francisco. The seminar had a standing-room-only crowd.

In March, a study by the Physician Insurers Association of America (PIAA), a national coalition of doctor-owned insurance companies, found that breast cancer misdiagnosis was the second most-common reason (behind birth-related problems) for which patients sued their doctors for malpractice. It reported that of all medical conditions, breast cancer ended up costing malpractice insurers the most.

Among these are a $3 million award to a Massachusetts mother of six, who was wrongly told that her mammogram was negative; $1.9 million to a New York woman who was told that her breast lump was the result of a muscle strain caused by coughing and $1.1 million to a Maryland woman who was told she was "cancer phobic" when she complained repeatedly about a bloody discharge from one of her breasts.

Because of concern over breast cancer lawsuits, many doctors are now taking steps to protect themselves -- steps that frequently benefit patients as well.

Boston breast-cancer expert Douglas Marchant told the doctors at the special seminar that they should devote more time to breast exams. And "if you find a mass," he said, "it has to be resolved, mammogram or no . . . You've got to do something about it."

Radiologists are being advised to make sure all mammogram results are communicated to patients, said lawyer Thomas Greeson, legal counsel to the American College of Radiology.

Attorneys for plaintiffs say that the increase in such lawsuits may reflect a rise in cancer rates, as well as a growing awareness among women that early detection can save or extend their lives.

Breast-cancer cases with the most merit for the plaintiff frequently involve a doctor who is "trying to be a nice guy . . . trying to placate a patient's concern (by saying) 'Don't worry, it's okay,' instead of doing what a doctor should do," said Philadelphia lawyer Aaron Blumberg, who argued Tobey Schriftman's case.

Many physicians and defense lawyers, though, blame greed among malpractice lawyers for the increase in breast-cancer lawsuits, accusing them of jumping into a large and lucrative field at a time when awards in another high-settlement area, birth-defect malpractice, seem to be falling off.

About 44,000 American women die from breast cancer each year, observed Philadelphia malpractice defense lawyer James Griffith, "and that's 44,000 potential new claims . . . (There is an attitude) that nothing ever happens to you in this country unless it's someone else's fault. It's not a question that God chose to give you a disease -- it's a question that the doctor had to screw up."

Griffith blames the American Cancer Society for creating unrealistic expectations among Americans, and juries, that in the case of breast cancer, "early diagnosis equals a cure."

To counter that, Griffith and other defense lawyers often win cases for their doctor clients by telling juries some depressing truths about breast cancer.

They explain that because breast cancer, which begins microscopically, doubles in size only every 30 to 100 days, a woman could easily have had breast cancer for eight years or longer before it grows to two centimeters, usually the smallest growth that can be detected physically by a woman or her doctor. They point out that even the best mammograms detect breast cancers that have already been there for years -- all that time with the potential for spreading to other sites.

What this means, Griffith and other defense lawyers frequently tell juries, is that even if a doctor errs by ignoring a cancerous lump, he or she cannot be held liable for causing injury to the patient -- because her cancer may already have spread and become deadly by then, no matter what the doctor did or did not do.

That argument figured in the case of Terri Barber, a Western Union worker and young mother who in August 1983 went to doctors at the Health Care Plan of New Jersey with complaints of a draining breast lump, which doctors initially treated with ointments. By the time she was diagnosed with a type of breast cancer called Paget's disease in March 1984, the cancer was found in her lymph nodes. A cancer expert, Harvey Lerner, chief of surgical oncology at Pennsylvania Hospital, testified on behalf of Barber's doctors that the disease already had spread to her liver by August 1983.

But the jury sided with Barber's attorney. who said in his summation: "We all know, ladies and gentlemen, people who live with breast cancer for many many years following fast and accurate diagnosis and treatment. Nancy Reagan, our First Lady, is a prime example . . . That was the opportunity, ladies and gentlemen, that was denied to Terri Barber."

Barber died in 1985, leaving a husband and 4-year-old son, the beneficiaries of her $850,000 award.