Hormone replacement therapy and breast cancer - debate rumbles on


Menopause News February 5th 2011


Letters about hormone replacement therapy and breast cancer in doctors' top journal show debate is still out there

It is now nearly 9 years since the Women’s Health Initiative (WHI) study found that HRT increases breast cancer. In spite of the huge decrease in hormone prescribing for menopausal symptoms since then, some doctors are still enthusiastic advocates of hormone therapy.

These contradictory opinions are very confusing for women and make it difficult for us to make an informed decision.

Three letters published this week in one of the world’s most prestigious medical journals, condense some of the main points about hormone replacement therapy and breast cancer from both sides of the debate (1,2,3).

Three of the most common arguments in favour of continued prescribing are:

  • that the dose and schedule of hormones used in the WHI study are out of date and that the lower doses and combinations used today are likely to be safer and need further study (1).
  • that younger women who start using HRT closer to the menopause or who use it for a short time are not at increased risk of breast cancer (1).
  • that the progestogen used in the WHI study was a synthetic progestin and that new compounds that contain naturally occurring progesterone are likely to be safer (2).

But the scientists who did the WHI study (3) refute these points with the following arguments against continued use of HRT:

  • While it is true that the WHI study used only one hormone regimen and dose and that lower doses are now more widely prescribed, there is no evidence that these other schedules are any safer.
  • With respect to natural (endogenous) progesterone, the evidence about safety is very shaky. There have been no randomised trials of this compound and the studies that have been done are observational (no controls) or preclinical and have had contradictory results. As a warning, the early combined HRT studies - which were also observational - gave no sign of the breast cancer problem. The only studies that can be trusted are those which use a randomised controlled design correctly.
  • Close analysis of the data from the WHI study showed that rather than being safe if used for a short time “a safe interval for combined hormone therapy use with respect to breast cancer cannot be defined.” (3)
  • HRT had the effect not only of increasing breast cancer risk but also of making diagnosis more difficult and therefore delaying treatment.

Professor Chlewbowski and colleagues do not mince their words:

"Many women with legitimate concerns about breast cancer would consider a drug resulting in a near doubling of breast cancer deaths (HR, 1.96; 95% CI, 1.00-4.04) to represent a substantial rather than a low risk.” (3)


Opinions differ about whether new trials should be done on these other hormone products, regimens and doses. But Chlewbowski and colleagues are clear: investigating non-hormonal treatments for climacteric symptoms should be a higher priority than doing more studies that are likely to show more of the same, about the hormone replacement therapy and breast cancer risk.


Bibliography

  1. Baber R. Breast cancer in postmenopausal women after hormone therapy. JAMA 2011; 305:466.
  2. Hermsmeyer RK et al. Breast cancer in postmenopausal women after hormone therapy. JAMA 2011; 305:466.
  3. Chlewbowski et al. Breast cancer in postmenopausal women after hormone therapy. JAMA 2011; 305:466-7.


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Published February 5th 2011.

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