Some things to know about progesterone therapy for cancer
A hormone-driven cancer (or hormone-sensitive cancer) is a type of cancer that uses certain hormones to grow and spread. These cancers have cells with receptors on their surface or inside them that bind to hormones like estrogen, progesterone, or testosterone.
Research shows that in many cases, blocking these hormone signals can slow or even stop the cancer’s growth.
This is why tamoxifen, a selective estrogen receptor modulator (SERM), is widely used in the treatment of estrogen receptor-positive breast cancer. It binds to estrogen receptors in breast tissue, blocking estrogen from activating them and thereby reducing tumor growth.
It’s not just about reproductive tissues and receptors.
Progesterone is usually considered a reproductive hormone, mainly associated with the menstrual cycle, pregnancy, and fertility. But progesterone receptors have been found in many other tissues, including the brain, thyroid, bones, pancreas, and colon. The same goes for estrogen receptors.
And interestingly, progesterone doesn’t always need to act through its receptor. Researchers have shown that it can influence cells through non-genomic pathways, meaning it can affect things like mitochondrial function, ion channels, and cellular membranes directly, even in cells that don’t express classical progesterone receptors.
A 2019 study published in Scientific Reports showed that high-dose progesterone significantly slowed the growth of glioblastoma, a type of brain cancer. Glioblastoma is not commonly considered “hormone-sensitive.” Researchers suggest that high-dose progesterone exerts its anti-tumor effects through mechanisms that may not rely solely on classical progesterone receptors.
The study found that progesterone:
- Reduced tumor size by nearly 50%
- Extended survival in mice with glioblastoma
- Inhibited glycolysis (the energy-making process cancer cells rely on)
- Induced senescence, pushing tumor cells into a non-dividing state
- Showed no toxicity to major organs
Histological sections of brain tissue show the effect of progesterone treatment on glioblastoma tumor size. Mice treated with 8 mg/kg of progesterone (PROG 8) showed a 21% tumor reduction, while those treated with 100 mg/kg (PROG 100) exhibited a 45% reduction compared to the untreated control (Vehicle).
Tumor volume over time in mice treated with progesterone. Both 8 mg/kg (PROG 8) and 100 mg/kg (PROG 100) doses significantly slowed tumor growth compared to the untreated group (Vehicle), especially between days 14 and 28 after treatment began.
Progesterone promotes order, not growth.
Unlike estrogen, which stimulates cell proliferation, progesterone promotes cellular differentiation. This means it encourages cells to mature into their proper form and function, which is the opposite of what cancer cells do.
In fact, some researchers have called progesterone a “differentiation signal.” It helps maintain tissue structure and function by supporting normal gene expression, enhancing mitochondrial performance, and reducing metabolic stress. These effects not only preserve the health of individual cells but also contribute to the broader order and resilience of surrounding tissues.
It’s also important to understand that estrogen, like progesterone, affects all tissues in the body, not just those involved in reproduction or those with classical estrogen receptors.
Progesterone restores mitochondrial function.
Progesterone can reduce reliance on glycolysis, the chaotic process cancer cells use to make energy under stress. Instead it encourages oxidative phosphorylation (the process healthy cells use to make energy).
Progesterone has been shown to activate enzymes that are needed to efficiently and completely produce ATP (energy) and reduce lactate buildup, a hallmark of the Warburg effect. It also stabilizes the mitochondrial membrane, protecting against swelling and permeability that typically precede cell death or dysfunction.
Progesterone supports a healthy immune system.
Progesterone is highly anti-inflammatory and helps regulate the immune system.
It lowers levels of inflammatory molecules like IL-6 and COX-2, which are often elevated around tumors and known to promote blood vessel growth, tissue invasion, and metastasis. It calms this inflammatory environment and supports the activity of natural killer (NK) cells, which helps the body detect and control abnormal cells before they can develop into cancer.
Progesterone affects nearly every tissue in the body, not just the reproductive organs.
Its cell-stabilizing effects support healthy function across many systems, including the brain, thyroid, colon, and bones. In many ways, progesterone is foundational to keeping cells organized, calm, and resistant to disease.
While it’s not widely used in conventional cancer treatment, progesterone helps prevent the kind of cellular chaos that drives cancer. I talk about it often because it’s safe, accessible, and worth considering, even when a cancer isn’t classified as “hormone-driven.” There’s more to its value than the presence or absence of a receptor.