Sometimes it seems like deja vu all over again...
In the cancer screening world, there isn't a more controversial topic in my opinion than the early detection of breast cancer, especially among women between the ages of 40 and 49.
We have been through repeated and intense discussions over the past 11 months as to whether women in this age group should be screened or have discussions with their health professionals on the benefits and risks of screening. And last week the fires heated up again with a study in the New England Journal of Medicine looking at women over age 50, and coming to the conclusion that the benefits of screening mammograms were "modest."
Today, we have another report in the journal Cancer (which in the interest of disclosure is published by the American Cancer Society, and whose editors are independent of the Society) that--especially given the media interest that has occurred already--suggests that screening women in their 40's significantly reduces the risk of death from breast cancer. And the question that most women and those that love them are asking is, "What the heck does all this mean for me?"
The study once again is an interesting one, well done by competent investigators.
In brief, the researchers looked at deaths from breast cancer in the entire country of Sweden with follow-up that averaged about 16 years.
They had the opportunity to look at counties in Sweden that offered screening mammograms to women in this age group, compared to counties that did not offer mammograms to this group of women over specific periods of time. They then compared death rates between the women in the two groups of counties, and determined whether or not screening mammography reduced deaths from breast cancer, or had little or no effect.
There is a bit of a twist in this study which is important to understand.
In Sweden, the counties could determine whether or not they were going to offer screening to this age group. If they decided to make that offer, they would invite the women to come in and get screened. Those women who took advantage of the invitation were in the "screened" group, and those women who did not take advantage of getting screened were in the "offered" group. Then, there were also the counties where women did not receive those invitations as a matter of public policy, for whatever reason--including whether or not the counties had the financial resources to offer screening through their health systems. Those women were in the "control" group.
The reason this is important is because the researchers were able to look at the effects of mammography on the entire population of women in the county who were offered screening and find out whether there was any difference in that group compared to women who decided not to get screened. This is an important distinction for many of us. There are some researchers who think it is the "invited group" that we should be looking at to determine whether or not mammography saves lives, while others say the real difference is most important in women who actually get screened.
This is actually a matter of significant interest to many of us here in the United States, since women in this country are aware of the benefits of mammography, yet many don't get the test or can't afford the test and the medical care if something abnormal is discovered.
So when we talk about the impact of mammography in the United States, we generally "roll up" the entire population of women. Many experts believe that the benefits of mammography would be much greater if more women got screened, while others argue that we have to deal in the real world where women frequently make the decision not to be screened, despite various organizations' recommendations.
So what did the researchers report?
After doing some very sophisticated analyses, the researchers concluded that women in the 40-49 years old age group who were invited to screening decreased their rates of death from breast cancer by 26%. When they looked only at women who actually got screened, that rate increased to 29 %. Both of these are very substantial numbers, and in their opinion showed a significant benefit for screening mammograms in women 40-49.
Does this end all the arguments about the value of screening in this age group? Probably not.
Recall that the United States Preventive Task Force last November made a recommendation that women between 40-49 not get routine screening mammograms. Instead, the Task Force recommended that women should have conversations with their health professionals to make a determination as to whether or not they want to get a mammogram based on their individual considerations, including the benefits/risks of the test. The American Cancer Society among others stood by their recommendations that women age 40 and older at average risk of breast cancer get a mammogram every year.
There are a couple of things that you need to consider in interpreting the impact of this current research report.
First, this report clearly shows a benefit to screening mammograms in this age group. However, as is always the case with all of the mammography studies and recommendations, there is going to be considerable discussion among the experts about what is right with this study, and what may be questionable, what questions it answers and what questions remain open. It is unlikely to be the definitive paper that brings an end to the discussion. And, disagreement is bound to continue.
Another point is that this is not the same type of study that was reported last week (and summarized at that time in this blog). It is a different method, a different group of women (40-49 vs. 50 and over) in different countries with different approaches to health care (although the article does point out that over time in Sweden there was standardization of approaches to breast cancer).
This research does not isolate out the impact of new treatments and increased self-awareness of breast lumps that was the cornerstone of the last week's report, although one could make the argument that there is an element of that built into this research as well (the researchers did look at breast cancer death rates in both groups of counties prior to the availability of widespread screening mammography and found little difference in that statistic, suggesting that the differences seen in screened vs. non-screened women was due in large part to mammography).
The authors also did an analysis of how many women needed to be invited to screening to save one life from breast cancer. That number was one of the reasons the USPSTF elected not to recommend routine screening mammograms in women ages 40-49. In the current study, 1252 women would have to be invited to screening over 10 years to save one life. The statistical analysis also suggested that number may be as low as 958 or as high as 1915. To some, that number may be sufficient to justify screening, to others it is too many women would have to be screened. In other words, it becomes a value judgment whether enough lives are saved from breast cancer in the 40-49 YO age group to justify screening.
So once again we are confronted with the "bottom line" question: what does this mean to me?
This study lends support to the current American Cancer Society recommendations that women at average risk should get a screening mammogram every year, beginning at age 40. However, that does NOT negate the fact that women--at all ages--understand the benefits and risks of screening mammograms. Mammograms are not perfect, and women need to know that. Mammograms may result in call backs for further studies, and women need to know that. Those studies can be painful, especially if a biopsy is involved. But that--again--applies to women of all ages.
We also need to understand--as I have written previously--that not all of the improvement in survival is due to screening mammograms alone. Increased self-awareness of breast lumps or other changes may well improve the odds that a woman will have a good outcome from treatment for breast cancer. The treatment itself has improved and accounts for part of the reason that survival from breast cancer has improved. But frequently, it is the mammogram that gets the woman to the treatment.
Sorting out the contributions of these factors in women in the 40-49 year old age group--and all age groups--is a difficult task, and the studies we have don't do a great job of helping us sort that out. So for now, the benefits of breast cancer early detection and treatment are due to--you guessed it--"all of the above."
We are probably never going to do the definitive study that would incorporate all of these questions and give us the "final answer." What many of us acknowledge is that we need better detection tests, especially tests that will help us understand which breast cancers are aggressive, and which are more indolent.
Until then, let's not forget that deaths from breast cancer have declined considerably in this country over the past 20 years. No matter the reason, that is something all of us can agree on and should celebrate.
Please note: I am travelling and unable to provide links for this post at this time because of time constraints, and in the interest of getting this posted as soon as possible.