Breast Cancer Rates (From NEJM 2007. 356 (16): 1670) 
The coincidence in timing between the drop in HRT use and the decline in breast cancer rates is postulated as additional evidence for the link between post-menopausal hormone use and breast cancer.
But a paper being published in the June 15 issue of Cancer suggests another possible explanation for the drop in breast cancer rates – a decline in mammogram screening. According to researchers at the National Cancer Institute, mammogram screening rates declined by 4% between 2000 and 2005.
Mammogram Screening Rates (Breen et al. Cancer. Online 14 May 2007)
If this is the case, then the decline in breast cancer incidence is not good news, but rather a harbinger of not-so-good things to come – namely, an increase in later stage cancers.
I suspect that the drop in breast cancer rates will ultimately be found to be due to a mixture of both effects – a decline in HRT use and a decline in mammography. But it’s going to be sometime before all of this is sorted out.
Rates of Confusion about HRT and Breast Cancer
In the meantime, I would not recommend using this new data as carte-blanche to restart HRT, nor am I changing my Rules for Prescribing HRT.
And ladies, please get your mammograms.
Since the effects of HRT are slowly additive (and breast cancer takes many years to develop – and at least 40% of brca are NOT estrogen receptor positive anyway) I doubt that the cessation of HRT (after the Women’s Health Study data were published) has much to do with the immediate drop in breast cancer rates. The drop in mammogram rates sounds like the more plausible explanation to me, given the time frame for cause/effect. What do others think?
This does sound possible (val jones’ comment) there wouldn’t be enough time, but still some cases might respond faster, right?
Val and MS ellis-
I encourage you to read the article in the NEJM, which gives credence to all sides of the argument, but argues that if the decline were soley due to a decline in mammography then the effect would have been the same on both ER+ and ER- tumors, which it was not. I’m not sure I buy that argument. But I still find the fact that the decline affected mostly hormonally sensitive tumors to be the most pursuasive in terms of the hormonal theory. And apparently, Val, the withdrawal fo hormones can indeed have a rapid negative impact on tumor growth and proliferation.
Oh, I tried: http://magpiemusing.blogspot.com/2007/05/why-women-avoid-mammograms.html
Question for you…a friend with breast cancer told me that her oncologist said that two years of consecutive nursing (i.e. two years with one kid vs. 6 months x 4 kids) was protective for breast cancer. You think that’s true? Any sources?
magpie,
your friend’s oncologist is absolutely right:
from uptodate, http://www.utdol.com/utd/content/topic.do?topicKey=breastcn/9760&type=A&selectedTitle=4~183
Of course, nothing is absolute, but it is fairly established that breastfeeding mothers have a slightly reduced risk of later developing breast cancer.
Overall rates of breast cancer began to decline in 1999, and a decreasing death rate from breast cancer can be traced back to 1990, long before the initial publication of the Women’s Health Initiative findings In July, 2002.
The time required for a malignant cell to develop into a clinically detectable breast cancer ranges from 2 to 26 years, with an average of about 8 years. It is difficult to understand how a decrease in HRT use would be reflected in a decrease in breast cancer rates within a year.
If the reported decreased incidence of breast cancer were due to a decrease in stimulation of subclinical tumors,the decreased incidence should be confined to small, early breast cancers. It was not.
The incidence of breast cancer increases with increasing age through and past menopause. If HRT stimulation of breast cells is responsible for breast cancer development, the incidence of breast cancer among postmenopausal women, most of whom do not take HRT, should decrease with age. It does not.
AVRUM-
Very persuasive arguments, indeed. I for one would LOVE IT if hrt were ultimately found not to cause breast cancers. Becasue there is no treatment for the symptoms of menopause that works as well as that stuff does…
MAGPIE –
That was a great post about how your mammogram got delayed. Very funny…
“I for one would LOVE IT if hrt were ultimately found not to cause breast cancers. “
Word. I have POF, and I’ve always planned to stop HRT when I hit 50.
Remembering the menopausal symptoms throughout my early and, especially, mid-30s before I was (finally) diagnosed at 38, I am dreading the day… Of course, NIH doctors say that symptoms are more severe in younger women, so I hope they are not going to be as bad when I am 50. But… I already have osteopenia. I would’ve just loved it to be able to continue for a bit longer without increasing my breast cancer risk above that of women who go to menopause in more normal age.