Do Hormones Cause Cancer?

Oct 24, 2022 | Hormones

One of the most dangerous misconceptions in healthcare remains the thought that hormone therapy is a direct cause of cancer. This topic becomes especially intense when discussing breast cancer and postmenopausal hormone replacement therapies (HRT).

The biggest question we get about hormone replacement therapy here at the Boulder Longevity Institute revolves around largely false assumptions that hormone therapies will increase the risk of cancer. Often, the patient is given this misinformation by another healthcare provider.

How is it possible that there are such strong feelings and determination behind what we now know is indeed a myth? Simply put – bad interpretation of results.

The trouble started with a study called the Women’s Health Initiative (WHI), which was aimed at discovering why postmenopausal women were so impacted by diseases like cardiovascular disease, breast cancer, colorectal cancer, and osteoporosis. The study, started in 1991, followed over 160,000 women aged 50 – 79 for years looking for potential risk factors.

Results posted in 2002 found that women taking a combination of estrogen and progestin (specifically Premarin) hormone therapy were at an increased risk of breast cancer, heart disease, stroke, blood clots, and urinary incontinence. While the study also found that there was a reduction in the risk of colorectal cancer and bone fracture, it determined these benefits did not outweigh the list of risks.

The result of the 2002 release from the WHI study was an immediate recommendation to stop hormone therapies in women. Thus, what we now know is an incredibly beneficial tool for longevity (hormone replacement therapy) became bad words in the healthcare world.

Unfortunately, as the authors of the WHI study would acknowledge, the study was flawed from the beginning. The selection of patients included a high number of symptomatic, postmenopausal women with known risk factors for disease like smokers, obese, and non-exercisers. The comorbidities of these study subjects alone flawed the future results.

In addition to a lack of diversity in participants, the authors acknowledged that the results of the WHI study were interpreted incorrectly. In fact, the results showed that women who were only on estrogen therapy (removing progestin from the equation) experienced reduced risks of breast cancer, heart disease, stroke, colorectal cancer, and osteoporosis. 

The contradictory data exposed following the WHI release was not published, meaning the last many people heard – hormone therapy was bad and not recommended. Newer data, in addition to the authors of the WHI study stating there were issues with their research, has disproved the WHI study but many in healthcare continue to ignore the new, advanced information.

A cumulative 20-year follow-up report on the WHI found that there was a lower breast cancer incidence and mortality rate in women who took estrogen alone. Thus, the recommendation should have been that we stop using progestins rather than eliminating hormone therapy altogether. 

We have narrowed in on why progestin is so problematic, which provides further evidence that hormone therapy in general is not the issue here. Progestin is not a progesterone. It does not fit the progesterone receptors properly. It does not impact the body the way progesterone does.

When progestin is eliminated and estrogen alone is considered, the benefits of estrogen hormone therapy greatly outweigh the risks. While oral estrogen does increase risks of coronary heart disease, stroke, and venothrombosis embolism, the benefits continue to surpass risks. Additionally, we do not recommend oral estrogen for these reasons – there are other ways to administer estrogen and other hormones.

We continue to receive confirmation that the cause of the extremely negative results and spread of misinformation in the aftermath of the WHI study was the inclusion of progestins in hormone therapy. 

In 2013, a 10-year follow-up from the randomized Stockholm trial determined that new incidences of breast cancer did not vary as the Stockholm trial originally indicated. The follow-up determined that any increased occurrence was due to higher progestin exposure – not to estrogen or progesterone therapies.

A more recent (May 2022) confirmation of the errors of the WHI study was recently published in The Cancer Journal. The review looked at decades of hormone replacement therapy after breast cancer studies (25 different studies). The studies spanned from 1980 – 2013 and the May 2022 review also looked at the previous 20 reviews of the studies. 

The May 2022 review found that one of the 25 studies, the HABITS trial, showed an increased risk of breast cancer recurrence. All the recurrence was local or contralateral with no metastasis. The HABITS trial is known to have included progestin therapy. The review found that only 22 of nearly a million people in the 25 studies (all 22 from the HABITS trial) showed an increased recurrence of breast cancer and those 22 people were also on progestin therapy.

More recently, a study published July 2022 in JNCI: Journal of the National Cancer Institute demonstrated that in postmenopausal women treated for early-stage estrogen receptor-positive breast cancer, neither vaginal estrogen therapy nor menopausal hormone therapy was associated with an increased risk of recurrence or mortality.

These recent studies, along with what we already knew, need to be paid attention to! When medicine makes a decision like, “No more hormone replacement therapies,” it has a hard time changing its mind. We must learn to look at the data and admit there is a better way.

The problem is not limited to postmenopausal women. Millions of men are being denied testosterone therapies because they have or have had prostate cancer. Meanwhile, the journal Nature Reviews Urology published an article reviewing a cohort and showing a 33% reduction in prostate cancer incidence in men with increased testosterone use.

Further, it appears testosterone replacement therapy may have a therapeutic role in active or previously treated prostate cancer. This belies the well-established theory since the 1940s that elevated serum testosterone levels are a causal factor in prostate cancer. We must challenge the long-standing (yet, incorrect) paradigm.

With all this new, modern information, we recommend that hormone therapy is safe, lifesaving, and vital to longevity. It is indeed the way to maintain muscle mass, libido, and quality of life as we age. Hormone replacement therapy has a beneficial impact on the brain and reduces the risk of fractures (which increase mortality risk within 10 years of the fracture.)

It is impossible to age in a healthy way without backing up the body with what it needs to survive. As data continues to mount showing the benefits of hormone therapies and disproving previous beliefs, we must have an open mind to change.

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