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Endometrial ca. risk - HRT/OCP

Discussion in 'Step I' started by rice_boy, Apr 30, 2007.

  1. rice_boy

    rice_boy Member 2+ Year Member

    Jul 15, 2006
    Hi, can someone answer this question -

    Combined HRT (estrogen + progesterone) does not increase the risk of endometrial ca. due to protection from progesterone.

    But, why is it that the combined oral contraceptive pill (E+P) decreases risk of endometrial ca. by 50% ?

    Whats the difference?

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  3. Idiopathic

    Idiopathic Newly Minted Lifetime Donor Classifieds Approved 10+ Year Member

    Apr 21, 2003
    OCP's allow you to menstruate normally. Thats the only thing I can think of. With combined HRT, you have no menstruation, which seems to be the protective factor (at least in my eyes).
  4. akpete

    akpete Drinks, anyone? 7+ Year Member

    Jun 14, 2004
    Aren't OCP mostly progestins? So your body ends up with less estrogen around leading to decreased endometrial cancer risk.

    Correct me if I'm wrong.
  5. joe6102

    joe6102 by the power of grayskull 5+ Year Member

    Mar 31, 2005
    Combined OCP's have much more estrogen than HT. Around 5 times as much.

    Maybe OCP's ensure that estrogen never goes unopposed for a much longer period. As in period of time. Not period as in......nevermind.
  6. bjackrian

    bjackrian Senior Member Physician Faculty 10+ Year Member

    Apr 16, 2004
    Denver, CO
    I could be wrong, but my understanding is that OCPs decrease endometrial cancer risk by causing inhibition to endogenous estrogens so you don't get estrogen spikes. I believe that it's the spiking estrogens levels that promote endometrial cancer while the low basal levels provided by the OCPs are not particularly harmful.
  7. rice_boy

    rice_boy Member 2+ Year Member

    Jul 15, 2006
    yep, my thoughts are tentatively along the same lines... neway... thx
  8. desire345


    Mar 18, 2009
    Bjackrian is absolutely correct.

    HRT vs. OCPS - In OCP's, the primary component is progesterone, and so that is the reason the estrogen doesn't go unopposed.

    Increased exposure or levels of estrogen is the cause behind breast, endometrial cancer, ovarian cancer etc - and in HRT we see that the estrogen component is greater. It is why in this case that OCPs cause a decreased risk of these 3 while HRT provides increased risk (and the chances of endometrial cancer is decreased given that progesterone is supplied along with the estrogen).

    I should also mention that HRT causes increases risk in thromboembolism, CAD, cholecystitis, stroke, risk of developing asthma, urinary incontinence in elderly, decline in cognitive function, evolution of Alzheimers, and it also lowers the seizure threshold. For this reason, ROUTINE use of HRT is not recommended. Main indication for HRT is hot flashes and osteoporosis. An alternative treatment that may be used is clonidine.

    Hope this helps.
  9. Dirt

    Dirt 7+ Year Member

    Jun 18, 2008
    From the earth.

    Hmm. I think combination pills for contraception tend to have much higher doses of hormones than HRT. From what I garnered, the general consensus on why there are differences as far as adverse effects are concerned between OCs and HRT has to do with the fact that with OCs you are modulating hormones that are already present, whereas with HRT you are essentially introducing hormones that are no longer around.

    I don't think that the dose of the hormones is really the issue, more so the difference between women in their reproductive prime vs. post-menopausal women as far as their general health and their hormonal state are concerned.
  10. SweetTonics

    SweetTonics 7+ Year Member

    Jan 26, 2007
    why clonidine? doesn't that just reduce sympathetic outflow?
  11. sime0n

    sime0n Junior Member 10+ Year Member

    Jun 12, 2006
    I still don't get why HRT causes cancer in post-menopausal women, but OCPs prevent cancer in pre-menopausal. Shouldn't the OCPs cause endometrial hyperplasia in the pre-menopausal if they contain even more estrogen + prosgesterone than HRT?

    Why can't we just give OCPs to the older women to prevent cancer then?
  12. Dirt

    Dirt 7+ Year Member

    Jun 18, 2008
    From the earth.
    The main cancer concern with HRT is breast CA. Obviously if you have an estrogen receptor pos. breast cancer, giving estrogen is a bad idea. OCPs and breast cancer are linked but the evidence is still a bit hazy from my understanding. The age of the typical patient on HRT vs OCP is a big reason for this difference.

    OCPs are protective for Ovarian CA simply because you don't get ovulation and thus repeated cycles of damage and repair to the germinal epithelium which can give rise to dysplasia etc.

    As far as endometrial CA, I think the key is again the age and hormonal state of the patients normally taking these things. OCPs lead to a decrease in the peaks and troughs of estrogen/progesterone and thus an overall decrease in the stimulatory effects of these hormones from what is physiologically normal. HRT is replacing hormones that are not normally present and therefore if unopposed lead to a marked increase in the stimulatory effect on the endometrium from what is physiologically normal at that stage in life. From what I understand the combo HRT does not have this effect and does not lead to an increased risk of endometrial CA.

    Of course this is mostly academic. The real reasons they don't give HRT to women is the risk of CAD, stroke and breast CA, all of which would be exactly the same if they were given OCPs.
  13. aashkab

    aashkab 2+ Year Member

    Dec 16, 2007
    Hey, you are basically right. And my interpreation of FIRST aid is that you don't give estrogen replacement therapy alone to post menopausal women because of all the cancer. so you add progesterone which gets rid of the cancer side effect. but now the problem is the increased CAD. so that's why its still only used for hot flashes/osteoporosis.

    so to summarize, OCP/HRT are basically the same thing. they both cause increased thrombolic events and disfavorable lipid profiles. its just that OCPs actually decrease cancer risk from preventing the estrogen surges, and ovulations, plus no pregnancy which is a HUGE benefit that outweigh the risk for CAD/CV events.

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