Estrogen Replacement Therapy Regains Favor : Health: A decrease in the hormone causes a wide range of effects in menopausal women. Studies show benefits outweigh risks.

Should a woman take estrogen when her body stops making it? The question stirs intense debate among health experts. It also provokes confusion and worry among the millions of American women who must decide whether estrogen replacement therapy is right for them.

When a woman reaches menopause, her levels of both estrogen and progesterone decline, and her ovaries stop releasing eggs. Menopause “officially” starts with a woman’s final menstrual period. The average age of onset is 51, but it can begin as early as 45 or as late as 55.

The drop in estrogen causes a wide range of effects, from relatively minor ones to some that can be life-threatening.

Doctors first used estrogen replacement therapy in the 1940s to ease the hot flashes and other discomforts that often accompany menopause.

In the ‘60s, estrogen therapy was acclaimed in a best-selling book called “Feminine Forever.” Women flocked to their doctors seeking this fountain of youth.

But this led to a ‘70s epidemic of uterine cancer. Estrogen users were found to have increased their risk for uterine cancer sixfold. More bad news came later, as research suggested a possible link between estrogen therapy and breast cancer. Not surprisingly, estrogen’s popularity plummeted.

Now, in the ‘90s, doctors are once again recommending estrogen replacement therapy for their patients, on the basis of recent medical studies as well as established benefits.

* Uterine cancer risk reduced. Researchers found they could counteract the risk of uterine cancer by giving estrogen in combination with a second hormone, progestin (a synthetic form of progesterone).

Progestin causes the uterine lining, the endometrium, to slough off monthly, thereby minimizing the risk of uterine cancer. Most women on estrogen now take progestin as well, and they run the same low risk of uterine cancer as women who take neither. (A woman who has had a hysterectomy can take estrogen without progestin, because she no longer has a uterus.) The use of reduced estrogen doses in recent years has probably also lowered the drug’s risks.

* Stressful symptoms eased. Some 80% of women entering menopause experience physiological disturbances known as hot flashes--abrupt feelings of heat flooding the upper body, often followed by drenching sweats and chills. Lack of estrogen can also leave the vaginal lining thin and dry, making intercourse painful. Similar changes in the urethra, the duct leading from the bladder, can cause urination to be painful as well. Other symptoms of menopause may include incontinence, dry skin, insomnia and mood swings. Estrogen therapy can effectively minimize or eliminate many of these problems.

* Fractures prevented. Estrogen helps prevent osteoporosis. This bone-thinning disorder affects four in 10 older women and is responsible for crippling and sometimes fatal fractures, particularly of the hip and spine. Studies show that postmenopausal women who take estrogen for six years or more reduce by at least 40% their lifetime probability of a fracture.

* Heart attacks prevented. Research over the last 15 years has demonstrated overwhelmingly that estrogen therapy can help ward off heart disease in post-menopausal women. This finding more than any other has swung medical opinion in favor of estrogen replacement.

Often thought of primarily as a man’s problem, heart disease afflicts one-third of American women ages 50 to 75. Because half these women die from the condition, heart disease has become the No. 1 killer of American women 50 and older. So far, 17 of 21 studies of estrogen’s effect on heart disease have found that it lowers a woman’s risk.

Despite its demonstrated benefits, estrogen therapy remains controversial. The main reason: Some studies suggest taking estrogen after menopause heightens a woman’s risk of breast cancer. Breast cancer strikes one in nine American women. Any drug that might add to that danger should obviously be taken with caution.

Since 1974, researchers have carried out more than 30 studies to determine whether estrogen therapy does indeed increase a woman’s risk for breast cancer, but a clear-cut answer remains elusive.

After analyzing 16 earlier studies on breast cancer and estrogen, the Centers for Disease Control reported last year that although it found no increased risk among women who used estrogen for less than five years, women who had taken it for 15 years had 30% higher risk of getting breast cancer than non-users.

Before making a decision about estrogen therapy, a woman must factor her own health profile into the equation.

Some women have little to gain. Dr. Wulf Utian, president of the North American Menopause Society and chairman of reproductive biology at Case Western Reserve University in Cleveland, pointed out that one in three women aren’t troubled by their menopausal symptoms and are at low risk for heart disease and osteoporosis. For them, he said, “estrogen therapy isn’t really justified.”

For other women, a personal or family history of breast cancer may rule out estrogen therapy.

Ultimately, a decision about estrogen therapy should be based on individual circumstances.