RESEARCH - Sudden decline in breast cancer could be linked to HRT

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Sudden Decline in Breast Cancer Could Be Linked to HRT

Medscape

Gandey

December 14, 2006 (San ) -- Breast cancer rates appear to be

dropping - especially in women over the age of 50 years - and new research

presented today suggests this surprising decline may be due to recent

changes in hormone replacement therapy (HRT) use. Reporting here at the 29th

Annual San Breast Cancer Symposium (SABC), researchers showed a 7%

drop in disease rates in 2003 - a dramatic fall that never before has been

observed in a single year. " Something went right in 2003, " lead investigator

Ravdin, MD, from the MD Cancer Center in Houston, Texas, told

reporters. " It seems that it was the decrease in the use of hormone therapy,

but from the data we used we can only indirectly infer that is the case. "

If this proves to be true, Dr. Ravdin noted, " the tumor growth effect of

stopping hormone replacement therapy is very dramatic over a short period of

time, making the difference between whether a tumor is detected on a

mammogram or not. " During the question period following the session,

attendees called the findings " fascinating " and " provocative. "

Another research team reporting in a recent issue of the Journal of Clinical

Oncology came to similar conclusions (e CA et al. J Clin Oncol.

2006;24:e49-50). " Hormone therapy use dropped 68% between 2001 and 2003, and

shortly thereafter we saw breast cancer rates drop by 10% to 11%, " lead

author A. e, MD, from the Northern California Cancer Center,

in Fremont, said in a news release. " This drop was sustained in 2004, which

tells us that the decline wasn't just a fluke. "

In the new study presented here, Dr. Ravdin and his team from the National

Cancer Institute and Harbor-University of California, Los Angeles Medical

Center looked at 9 regions in the United States. Analyzing data from the

Surveillance Epidemiology and End Results (SEER) database, they found that

the incidence of breast cancer increased 1.7% per year from 1990 to 1998.

But then rates began to decline, and between 1998 and 2003, the incidence

decreased by 1% each year.

Decrease Greater in ER-Positive Invasive Tumors

The sharpest drop of 7% was observed in 2003. This decline was seen both for

in situ cancers (5.5%) and malignant cancers (7.3%). The researchers report

that the decrease in incidence was greater in ER-positive invasive tumors

than ER-negative tumors (8% vs 4%). When the analysis was restricted to

patients 50 to 69 years of age, this difference in decline in the incidence

by ER was more striking (12% vs 4%).

" The researchers present a very positive message about incidence, " session

comoderator e Piccart-Gebhart, MD, from the Jules Bordet Institute, in

Brussels, Belgium, said during the meeting. This positive message surprised

even the team itself. In an MD news release, senior author

Berry, PhD, admitted that he did not expect to observe the magnitude and the

rapidity of the decline in incidence. But, he added, it makes perfect sense

if it is considered that use of hormone therapy may be an important

contributing factor to breast cancer development.

Research suggests that ER-positive tumors will stop growing if they are

deprived of hormones. Dr. Ravdin estimates that about 30% of women over the

age of 50 years had been taking hormone replacement therapy in the early

years of the new millennium and that about half of these stopped treatment

in late 2002 after the results of the Women's Health Initiative study were

announced.

That trial looked at more than 16,000 women over the age of 50 years using

hormone replacement therapy and was prematurely stopped when the combination

of estrogen and progestin was found to significantly increase the risk of

developing invasive breast cancer. " It is possible that a significant

decrease in breast cancer can be seen if so many women stopped using

therapy, " Dr. Ravdin said. " But whatever the cause, " he said at the meeting,

" we know that this decline is a real effect, not just a statistical

anomaly. "

29th Annual SABC: Abstract 5. Presented December 14, 2006

http://www.medscape.com/viewarticle/549425

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