Good Science, Bad Conclusions

Sometimes you are taken a bit by surprise. When that happens to me, I have learned the real "surprise" may not be what it appears to be.

Yesterday's report from the San Antonio Breast Cancer Symposium that the incidence of breast cancer fell dramatically between 2002 and 2003 was one of those surprises.

Not that we weren't aware that the incidence of breast cancer was either leveling off -- or actually decreasing -- but we were surprised at the magnitude of the change.

But what has me concerned is the rush to judgment by some experts and much of the media as to the explanation for this apparent welcome news.

They are saying that this is due to a single factor: the decrease in the use of hormone replacement therapy.

I do not agree. There is something going on here that just doesn't add up.

The researchers who presented this abstract are "top drawer," and highly regarded in the research and medical communities. I do not dispute their methods or their findings.

I am concerned about how those findings have been reported by the media, and the implications of the various expert sound bites that may not be putting the whole story into its proper perspective.

Let's take a moment to examine what the researchers reported. The researchers looked at data collected from 1990 through the end of 2003 on breast cancer incidence. We know that from 1990 through 1998 there has been an increase of 1.7 percent per year in the number of breast cancer cases diagnosed. From 1998 until 2003, there was actually a decrease averaging 1 percent per year.

What was striking in the research was that in 2003 alone, there was a decrease of 7 percent in the incidence of breast cancer in that single year.

The authors note in their abstract that this decrease appeared to begin in early 2003 and accelerated later in the year.

The decrease was most notable, according to the authors, in women in their 50s, 60s and 70s (11 percent, 11 percent and 7 percent declines, respectively) and in women with hormone-positive tumors. The authors conclude that the decline could be due to the 2002 publication of a study demonstrating the risks of hormone replacement therapy (HRT) that led many women to stop HRT involving estrogen and progesterone.

Over the next several years, numerous experts dissected the results of the study and made several criticisms, which were widely shared in the medical community.

Today, when it comes to combined HRT, the recommendation is "as low a dose as possible, for the shortest time possible consistent with effective control of menopausal symptoms."

But there is another wrinkle in the picture that hasn't been considered in this discussion.

When my colleagues here at the American Cancer Society reviewed similar data this past summer, they were concerned that the news was not altogether good, and that the drop might have something to so with mammography use having stabilized and perhaps decreased.

In a report in the medical journal Cancer Epidemiology Biomarkers and Prevention, researchers point out that we may actually be diagnosing fewer cancers, explaining at least some of the drop (about one-third of it).

So what does all of this mean? I, for one, have a real concern that what we may be seeing is not necessarily a rosy scenario.

Please do not misunderstand or misinterpret my motives when I make these comments. If we are actually seeing a dramatic decrease in the number of breast cancers, and it is real, then that is terrific news.

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