Lesson 5 Estrogen and Cancer: A Call for Caution

Estrogen and Cancer: A Wake-Up Call

In a report published in USA Today on January 6, 2003, it was revealed that the federal government has officially recognized the use of steroidal estrogen in postmenopausal hormone therapy and oral contraceptives as known human carcinogens. An advisory panel of the National Institute of Environmental Health Sciences made this ruling due to the association between steroidal estrogen and endometrial cancer, as well as a lesser extent of breast cancer. This addition brings the total number of substances recognized as posing a cancer risk to 228. However, the report does not address the potential benefits these products may have. It does mention that birth control pills containing estrogen might offer protection against ovarian cancer.

The Warning on Estrogen – February 23, 1994

Another warning regarding estrogen was given on February 23, 1994. Researchers highlighted the growing link between environmental estrogen and breast cancer, emphasizing the need for prevention. Hormone replacement therapy (HRT) was found to interfere with the metabolism of natural estrogen. Dr. Elihu Richter, from Hebrew University, presented findings at the American Association for the Advancement of Science, revealing an 87% increased risk of breast cancer for women aged 60 to 66 on estrogen replacement therapy. While estrogen replacement therapy can reduce the risk of heart disease and osteoporosis, it carries the highest risk for cancer. Dr. Graham Colditz from Harvard Medical School raised the question, “Should breast cancer be the price we pay for a reduced risk of heart disease and fractures?” His answer was a resounding no.

These reports highlight the need for caution when considering the use of estrogen and its potential risks for developing cancer. It is essential to weigh the benefits against the possible harms and make informed decisions regarding hormone replacement therapy and oral contraceptives.

Rethinking HRT: New Findings Shed Light – September 2002

In a groundbreaking study called the Women’s Health Initiative (WHI), the long-standing beliefs surrounding hormone replacement therapy (HRT) were challenged, leading to a reevaluation of its risks and benefits. The outcomes of this study, which involved a large number of women, have left many HRT users contemplating their choices.

Traditionally, it was believed that HRT, specifically the combination of estrogen and progesterone, could lower the risk of heart disease and contribute to overall well-being. However, the WHI study revealed surprising results. Contrary to expectations, long-term HRT use not only failed to reduce the risk of heart disease but actually increased the likelihood of developing cardiovascular problems and breast cancer.

The study monitored over 16,000 women between the ages of 50 and 79 who were either taking a combination of estrogen and progesterone or a placebo. Initially intended to continue until 2005, the study was cut short when it became apparent that the risks associated with HRT outweighed any potential benefits. Women on HRT were found to have a higher risk of invasive breast cancer, strokes, heart attacks, and blood clots compared to those who did not take the hormones.

Interestingly, the study did highlight a reduced risk of colon rectal cancer and hip fractures among women using HRT. However, these findings were overshadowed by the significant increase in breast cancer and cardiovascular risks.

The unexpected revelations from the WHI study cast doubt on previous research conducted on HRT, leading to its premature termination by the National Institute of Health due to ethical concerns. Medical professionals were promptly advised to discontinue long-term HRT prescriptions based on the study’s findings.

Dr. Susan Fletcher and Dr. Graham Colditz of Harvard Medical School, in an accompanying editorial to the study, emphasized that the aim of prolonged estrogen and progestin therapy was to promote health and prevent diseases. However, the study provided compelling evidence that the opposite was occurring, even if the associated risks were relatively low. In light of these findings, they strongly recommended that clinicians refrain from prescribing HRT for long-term use, as the risks clearly outweighed the benefits.

Furthermore, the study challenged the notion that HRT effectively prevents fractures caused by osteoporosis. Surprisingly, women on hormones showed a slightly higher rate of hip fractures compared to those who received the placebo, contradicting previous assumptions.

It is important to note that the WHI study employed a widely used but synthetic hormone medication known as Prempro, which combines Premarin (estrogen derived from pregnant horses’ urine) with synthetic progestin. Although more research is necessary, there are indications that lower doses of bioidentical hormones, which closely mimic those naturally produced by the human body, may offer a safer alternative. However, there haven’t been sufficient follow-up studies on bioidentical hormones to draw definitive conclusions regarding their risks and benefits.

The groundbreaking findings from the WHI study have prompted a significant shift in our understanding of HRT. It is crucial for both medical professionals and women to reconsider the risks and benefits associated with hormone replacement therapy and explore alternative approaches to managing menopausal symptoms.