A government advisory panel has expressed "serious concern" about the cancer-causing potential of a drug called DES in the estimated 2 million women who took it to try to avert miscarriages.

A statiscally significant relationship linking use of the hormone diethyl shilbestrol in pregnancy to the risk of cancer of the breast, uterine cervix, lining of the uterus, or ovaries "is unproved," the DES Task Force said in an intial report.

But the relationship "is suspect," and "prudence dictates" not only "careful follow-up of women exposed to estrogens in the past," but also careful judgement in exposing such women to additional hormone treatment, the task force told the Department of Health, Education and Welfare.

A copy of the report, dated Tuesday, was obtained yesterday. An HEW spokesman had no immdeiate comment, saying that the report had not been received by Assistant Sectetary of Health Julius Richmond, to who it was addressed.

HEW Secretary Joseph A. Califano Jr. set up the task force on Feb. 3,71/2 weeks after the nonprofit Health Research Group disclosed that an analysis of "preliminary evidence showed abnormallproductive organs in women who, while pregnant, took large doses of DES at the Universityof Chicago's Lying-In Hospital during a 20-month study in 1951-1952.

Together with data from animal experiments and from studies of other gives the task force members "serious concern about the carcinogenic potential of DES" in the users, the report said.

The 1951-1952 study was a careful test of manufacturers' claims that DES prevented miscarriages. University scientists found no substantial evidence of effectiveness. But doctors continued to prescribe DES massively for a quarter century afterward.

During a follow-up of children born to DES mothers in the study, a nurse noted and reported that many women who had taken the estrogen appeared to have died of breast cancer. This led to a proposal for a study of 693 women who had taken DES, and 668 comparable women who had not.

The National Institutes of Health agreed to fund the study. The university reported preliminary results last Aug 31 to NIH. The results were analyzed by Dr. Sidney M. Wolfe, director of the Health Research Group, which is financed by Ralph Nader's Public Citizen Inc. This led to the formation of the task force.

As summarized by the task force, the data show that 46 of the DES women developed cancers, compared with 30 of the controls.

While these date "provide serious cause for concern, there is a need for coution in assuming that they show an association between the maternal use of DES and the subsequent occurence of cancer," the task force said. "The differences... are based on a relatively small number of cancers, and could be due to chance alone."

Prescribing of DES began to fall sharply in 1971 when researcinal cancer in the daughters of women who had taken it while pregnant as much as 24 years earlier.

In December 1975, scientists found that thousands of sons of DES mothers had birth defecxts of the reproductive tract, includeing low sperm counts indicating possible sterility.

In specific recommendations, the task force said that HEW should:

Inform women who are exposed in pregnancy to DES of the task force's conclusion.

Notify all physicians of the task force's concerns about mothers who were exposed to the drug and encourage the doctors to inform women they had exposed to the drug during pregnancy.

In addition, the task force advised women who were exposed to DES to notity their doctors and to tollow certain medical-care guidelines.

These include an annual pelvic examination with a so-called Pap smear and a monthly breast self-examination.

As for mammography, the report said it should not be done at all by a woman under 35, should be done annually by a woman 35-39 only if she has a personal history of breast cancer, and should be done annually by a woman 40-49 only if she has a history of breast cancer in immediate relatives, or a personal history of the disease. Over age 50, annual mammography "may be considered," the reporn who have been exposed to DES to minimize use of others drugs consisting of or including estrogens.

The report also discouraged the use-estrogens by menopausal and post-menopausal women.