Dr. Heward explains why there are increased breast cancer incidences seen when studying women who are taking hormone replacement therapy/HRT.
When we do a study where we compare women on estrogen with women who don’t go on estrogen, we report that the women who got estrogen got more breast cancer and the conclusion or the implication is that somehow estrogen caused that breast cancer. But, there are no data, to my knowledge, and remember I am a molecular endocrinologist so I study how hormones work at the molecular level, and there are no data, anywhere I know of that indicate that estrogen has the ability to take a normal, healthy breast cell and change it to a cancer cell. That does not happen.
So how then can we explain the increased incidents of breast cancer in women on estrogen replacement therapy, and the answer is, what we do know about estrogen is that it’s a trophic hormone which means it stimulates growth in some of the tissues in which it has receptors, like the breasts. So, if I took estrogen, my breasts would grow.
In a woman who has an estrogen-sensitive breast cancer, estrogen may actually stimulate the rate of growth in the cancer itself, so during the time frame of the study, are you more likely to pick up a fast-growing cancer or a slow-growing cancer? What’s probably going on is there’s no more breast cancer in the estrogen group than there is in the control group, but just more diagnosed breast cancer because the tumors are growing faster.
About Dr. Heward, Ph.D:
Dr. Christopher B. Heward is past-President of Kronos Science Laboratory. His primary responsibility was providing scientific and technical leadership for all laboratory activities. He oversaw the development and implementation of the clinical laboratory testing program; assisted in designing and refining both internally and externally sponsored clinical studies; directed and coordinated diagnostic product research and development; administered laboratory and patient databases; was principal investigator for the Kronos Longitudinal Aging Study (KLAS); and communicated Kronos’ discoveries and advances to lay and scientific audiences via presentations and publications. Dr. Heward’s research interests included healthy aging, endocrinology, oxidative stress, Alzheimer’s disease, prion disease (TSE) and menopause. Dr. Heward attended the University of Arizona and received a Bachelor of Arts degrees from both the Department of Psychology and the Department of Chemistry, as well as a Bachelor of Science degree from the Department of Biology. He earned his PhD from the Department of Biology in 1981.
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