New Study Suggests Breast Cancer/Oral Contraception Link

A new study released this week suggests that there is a link, (a fairly significant-sounding link actually), between breast cancer and oral contraceptives. What the study has going for it is that it was published in the very legitimate, peer-reviewed journal Mayo Proceedings, from the Mayo Clinic. But while we are not inclined to question the integrity of the Mayo Clinic, we do think there are some serious questions to be considered about the report.

First, the report's lead author, Dr. Chris Kahlenborn, is associated with the "The Polycarp Research Institute," (TPRI) whose website includes this statement of itself:

"TPRI will support research efforts that improve the spiritual condition of men and women, and will not promote methods or intentions that are inconsistent with the ethical and moral guidelines of the Catholic Church…"

For the purposes of the Mayo article, Dr. Kahlenborn lists his email as, and his mailing address as "Department of Internal Medicine, PO Box 263, Hollidaysburg, PA." Seem strange to you that a doctor associated with a "Department of Internal Medicine" would prefer his email at his nonprofit instead of at his hospital or medical school? Well, one reason here might be that there is no hospital in Hollidaysburg, PA. Another might be that that mailing address is actually the EXACT SAME address that TPRI lists on its website. From the looks of it, Dr. Kahlenborn just felt like being associated with a "Dept. of Internal Medicine," so he made one up.

Another co-author, Dr. Francesmary Modugno, was a computer science specialist (that's actually her PHD), who got a Master's in Public Health in 1998 and has since fervently devoted her research to trying to establish a link between contraceptives and breast cancer.

The other two co-authors, however, do not show as clear signs of activism: Dr. Potter is an established biostatistician, and Dr. Severs, a professor emertius of Penn State University, is even cited by the ACLU as a co-author of a study denying the link between abortion and breast cancer.

So what to make of this new study? First, it seems quite reasonable to hold it suspect on the grounds of Dr. Kahlenborn's and Dr. Modugno's apparent ideological commitment to establishing such a link. And regardless of any ideological commitment to establishing this link, it seems reasonable to hold any medical research institution suspect which explicitly states that their research will not deviate from religious dogma.

Consider this article from PATH which suggests the opposite, or try a Google search of "contraception" and "breast cancer" to see what else you come up with — most research suggests that the link between hormonal contraception and breast cancer is inconclusive, or that it is a minor link in some specific circumstances. The National Cancer Institute for example has a sober-minded fact sheet published on the issue. Or from the WHO's website:

Concerning breast cancer (and hormonal contraception)…even if the association is causal, the excess risk for breast cancer associated with patterns of use that are typical today is very small…

This new paper's author makes some alarmist sounding statements, particularly in the press release regarding the paper in which he says, "The risk association was 44% over baseline parous women (having been pregnant) who took OCs prior to their first pregnancy." It sounds scary, and it has far-right groups not only reiterating the claims (like Dr. Janet Smith's "One More Soul"), but twisting them further. turns that 44% into "over-all risk increase for breast cancer of 44 percent." Bad reporting certainly. But bad science too?

The verdict on whether this is bad science is still out, and I'll leave that to more expert voices who will hopefully revisit this issue soon on our website. In the meantime, it is safe to say that doctors with clear ideological persuasions making bold claims like this tend to undermine their own work, regardless of its quality. If there really was such a risk for breast cancer (remember, major medical organizations don't seem to think so), the public would deserve to know, but they need the news from a source they can trust.

And the fact that right-wing media outlets pick up questionable research and blatantly misreport it, making much more far-reaching claims than the actual research, is…? Well, I guess by now it's just expected, and that's why we're asking questions.

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  • nrfc

    This is not the only recent study that links contraception and breast cancer.

    Other studies recently published in the January 2006 edition of the New England Journal of Medicine and the October 2006 edition of Cancer Epidemiology Biomarkers & Prevention support the connection.

    More information on this issue can be found at:

    Breast Cancer and Oral Contraception

    Additionally, in 2005 the International Agency for Research on Cancer (part of the World Health Organization – WHO) declared combined estrogen-progestogen contraceptives (used for birth control) as being “carcinogenic to humans.”

    Depending on Google search results to settle this issue is not very wise either. Google is just going to return results from organizations which have outdated information about this topic

    Many organizations, such as the Susan G. Komen Breast Cancer Foundation, have old data on their websites. Though the Komen foundation recognizes that OCs increase the risk of breast cancer to some degree, their data is from 2003 or earlier. Depending on Google results for up to date and accurate information is not advisable to say the least. Quite often old and outdated information is returned, even from recognizable organizations and institutions.

    The reason some major medical organizations won’t admit (or grudgingly admit) the link is for the very reasons you bring up — the people who run them have their own agendas! They really have a hard time admitting that yes, there appears to be a link. Instead they minimize it away, or simply state the benefits outweigh the risks, or state that a very small number of users will develop breast cancer.

    But breast cancer is deadly, even localized breast cancer associated with contraception use. How many women have to die before it becomes a significant number? I believe that one death as a result of contraception associated breast cancer is one death too many. Can you agree with this?

    If this were the sole study making such a link between breast cancer and oral contraceptives, then one could certainly point out that the agenda of the author(s) may have had a significant influence on the findings. Yet since other studies support the link, it’s not much of an issue.

    Ruben Obregon


    The No Room for Contraception Campaign

  • ian

    Several points in return for Ruben's comments above… 

    Yes, others studies suggest a link too — I don't believe I said this is the only such study.  But the way you quote those other studies sounds hysterical compared to the studies themselves.  The very same scientists he relies on don't make the same conclusions that he does.

    For example, the study from Cancer Epidemiology Biomarkers & Prevention states:

    We found no evidence overall that use of oral contraceptives for at least 1 year is associated with breast cancer risk for BRCA1 and BRCA2 mutation carriers before age 50. For BRCA2 mutation carriers, use of oral contraceptives may be associated with an increased risk of breast cancer among women who use them for at least 5 years. Further studies reporting results separately for BRCA1 and BRCA2 mutation carriers are needed to resolve this important issue.

    And IARC's statement on this issue includes the following:

    Use of OC's increases risk of breast, cervix and liver cancer…
    There is a small increase in the risk of breast cancer in current and recent users of oral contraceptives. However, ten years after cessation of use, the risk appears to be similar to that in never-users. The risk of cervical cancer increases with duration of use of combined oral contraceptives. The risk of hepatocellular carcinoma is increased in long-term users of combined oral contraceptives in populations with low prevalences of hepatitis B infection and chronic liver disease – two major causes of human liver cancer.

    … but decreases risk of endometrial and ovarian cancer
    In contrast, the risks of endometrial and ovarian cancer are consistently decreased in women who used combined oral contraceptives. The reduction is generally greater with longer duration of use, and some reduction persists at least 15 years after cessation of use.

    More work needed to assess risks and benefits

    The research suggests a minimal link if any conclusive link can be established at all, as well as concluding that links exist in specific cases that don't exist in others — the danger is not applied across all users.  And these studies suggest the need for more studies, apparently to help aid in making conclusions about action.  They do not suggest that oral contraception should be abandoned, as Ruben's group does. 

    There also remains something very strange to me in Ruben's claims and others made by his allies that every major medical organization's recommendations on oral contraceptives should be disregarded because "the people who run them have their own agendas," when he and his colleagues provide citations primarily to religious organizations with explicit dogmatic objections to contraception of any kind.  See his web site's "Links" page for an example — not a mainstream scientific reference among them. 

    On the other hand, if organizations that we cite on this website have ideological biases, I would suggest that a major bias is toward credible evidence, and the credible use of that evidence.  Based in that evidence, further positions tend to be chosen based on bringing the best health care and quality of life to people.

    As to Google: I was not suggesting that Google is a reliable academic research tool.  My suggestion, I thought, was obviously anecdotal.  Since I was wrong about its obviousness, I'll remind readers that Google aggregates its returns for searches based on what it interprets is a site's significance within the web — top search results for something like this tend to represent the most mainstream, or at least most commonly linked-to, websites.  Furthermore, my point at the end of that sentence — "most research suggests that the link between hormonal contraception and breast cancer is inconclusive, or that it is a minor link in some specific circumstances" — is supported by the same research Ruben quotes himself as "cutting-edge" and in support of his own claims.

    And as to whether or not "one death…is one too many," I'll remind other readers that this is the right's favorite stickman argument for this and similar points when trying to win over readers.  I do not take deaths lightly at all and believe that precautions should be taken with dangerous drugs and that consistently harmful drugs should be carefully evaluated.  But this point is used by Ruben rhetorically, not literally — you don't see his group and others like them taking on Viagara (which has killed people) or having led the charge against Vioxx.  The point here for them is not about deaths from legal drugs.  It is about trying to undermine contraception.  Period.