Know the Facts - Does Bioidentical Progesterone Pose a Cancer Risk?

Marshall Medical Group • May 19, 2025

Bioidentical progesterone, when used appropriately and under medical supervision, does not appear to pose the same cancer risk as synthetic progestins, particularly in the context of hormone replacement therapy (HRT) for menopausal women. Here's a more detailed breakdown:

1. Breast Cancer Risk

  • Synthetic progestins (e.g., medroxyprogesterone acetate) have been associated with an increased risk of breast cancer when used in combination with estrogen.


  • Bioidentical progesterone (e.g., micronized progesterone) has not been shown to significantly increase breast cancer risk and may even be associated with a lower risk compared to synthetic progestins.


  • Study found that women using estrogen with micronized progesterone had a lower risk of breast cancer than those using estrogen with synthetic progestins. 

2. Endometrial Cancer Risk

  • Unopposed estrogen therapy {i.e., estrogen without progesterone) can increase the risk of endometrial {uterine) cancer.



  • Adding bioidentical progesterone protects the endometrium in much the same way as synthetic progestins, reducing this cancer risk.

3. Other Cancers

There's limited evidence linking bioidentical progesterone to increased risk for other cancers {e.g., ovarian, colorectal), but overall data are still evolving and not conclusive.

Bottom Line:

Bioidentical progesterone is generally considered a safer option than synthetic progestins in terms of cancer risk, particularly for breast and endometrial cancers. However, it should still be: 

  • Prescribed and monitored by a qualified healthcare provider


  • Tailored to individual risk factors and medical history


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