Health Briefs

July 19, 2002

More Bad News About Hormone replacement Therapy

Last week’s report from the Women’s Health Initiative study confirmed that chronic hormone replacement therapy (HRT) with estrogen and progesterone increases the risk of both breast cancer and heart disease.  In this week’s Journal of the American Medical Association, the impact of HRT on the risk of ovarian cancer was also evaluated.  The study observed more than 44,000 women who were taking HRT between 1979 and 1998.  A total of 329 of the women developed ovarian cancer during the course of this study.  Among women using estrogen alone as HRT, the study found an increased risk of developing ovarian cancer.  (Most women taking estrogen-only HRT have previously undergone hysterectomy, as “unopposed” estrogen also increases the risk of uterine cancer.)  Increasing duration of estrogen use was associated with a progressively greater risk of ovarian cancer.  Among the women who used estrogen for 10 to 19 years, the risk of developing ovarian cancer was 80% higher than the incidence observed in the women who did not take HRT.  Moreover, taking estrogen-only HRT for more than 20 years was associated with a 220% increase in ovarian cancer risk.  However, the relatively recent practice of combining continuous estrogen and progestin in one pill made it difficult for this study to identify any clear trends about the risk of ovarian cancer associated with this so-called combination HRT.

Just over 23,000 cases of ovarian cancer will be diagnosed in 2002 in the United States, making this the 7^th most common cancer among women.  Ovarian cancer is the 5^th leading cause of cancer death in women, and 14,000 women will die of the disease this year.  One must remember that the total number of ovarian cancer cases, compared to other cancers, is rather small, and that the increase in risk identified in this study is relative to the already low incidence of this disease.  However, cumulative exposure to estrogen HRT nonetheless appears to raise the risk that a woman will develop both ovarian and breast cancer.  Taken together, the most recent evidence for the potentially life-threatening effects of long term HRT should give both physicians and patients an impetus to further study non-hormonal approaches to the treatment of menopausal symptoms.

It has long been observed that carrying a baby to full-term, particularly before mom reaches age 30, reduces the risk of breast cancer.  The breasts are also thought to undergo further favorable changes during lactation, and these changes appear to render the cells inside the milk ducts less susceptible to precancerous and cancerous changes.  The current issue of the journal Lancet reports on a huge study involving more than 147,000 women from 30 different countries.  The data was compiled from 47 different research studies, and determined that the risk of developing breast cancer was reduced by 7% per year following each full-term birth, and by an additional 4% for every 12 month period of breastfeeding.  These findings were consistent among women from both industrialized societies and from developing countries.   This is the first study that has specifically looked at the effects of full-term pregnancy and breastfeeding, both together and separately, in terms of overall breast cancer risk. The greater tendency for mothers in developing nations to breastfeed their babies than mothers in industrial countries may, at least in part, account for the greater incidence of breast cancer seen in the developed world.

Little baby boys result from the union of mom’s egg, which contributes an X-chromosome, and dad’s sperm, which must contribute the necessary Y-chromosome.  If the sperm contains an X-chromosome, then a little girl is the result.  In 1979, a large spill of polychlorinated biphenyls (PCBs) occurred in Taiwan.  These petroleum derivatives are frequently used in electrical transformers and in other industrial applications.  They are chemically very stable, and persist for a very long time if inadvertently released into the environment.  PCBs have previously been linked to cancer, and to diseases of the immune, reproductive, nervous and endocrine systems of animals.  Children born to women who have been exposed to PCBs in the workplace are often born prematurely, and have decreased birth weights.  Although the manufacture of PCBs was outlawed by Congress in 1976, more than 1.5 billion pounds of PCBs were manufactured in the United States before the ban took effect in 1977.

In the journal Lancet, a new study reports that men exposed to PCBs during a major PCB spill in Taiwan, in 1979, had a 45% lower chance of fathering baby boys than men who were not exposed.  This effect was especially pronounced in men who were exposed to PCBs before the age of 20.  This study, once again, points to the pervasive health effects of PCBs, and the need to eliminate even small amounts of PCB contaminants in the environment.

Dr. Robert A. Wascher