Welcome to episode 2 of my crusade to highlight the dangerous lies, half-truths, and inaccuracies being perpetuated by the students over at 1Flesh. Be forewarned, this post is long, mainly because I threw in some extra information about breast cancer and statistics to make things clearer for everyone, but it’s totally worth the read to the end. Promise.
This post deals with a second claim by 1Flesh, specifically the disproven idea that oral contraceptives (OCs) increase the risk of breast cancer. As before, paragraphs in all italics are taken from 1Flesh’s site, just so there’s no confusion.
Let the games begin!
|Graphic from 1Flesh – Damn, they have nifty graphics|
The Pill increases a woman’s risk of breast cancer.
Huzzah for overarching, inaccurate statements of little value! Or rather….not. How about a more accurate statement? One like:
“Certain formulations of oral contraceptives (OCs) may increase the risk of certain types of breast cancer for certain women, particularly if taken for longer intervals.”
Before we go any further, though, let me share a quick primer on breast cancer in the US, and the different types of breast cancer, particularly since 1Flesh seems keen on highlighting very specific types and the possible increased risk of these very specific types on very specific women.
A few quick facts:
- Approximately 1 in 8 US women will be diagnosed with breast cancer in her lifetime.
- For women in the US, breast cancer death rates are higher than any other cancer death rate except for lung cancer, and breast cancer is the second highest diagnosed cancer, ranking just behind skin cancer.
- Approximately 5-10% of breast cancers can be linked to inherited gene mutations, while approximately 85% can be linked to life events.
- The most significant factors for the risk of breast cancer are sex (being a woman) and aging.
- In 2012, an estimated 226,870 women in the US will be diagnosed with breast cancer and an estimated 39,510 women will die from the disease.
Further, from WebMD:
One of the primary ways breast cancer is classified is as one of the following:
- Endocrine receptor (estrogen or progesterone receptor) positive
- HER2 positive
- Triple negative, not positive to receptors for estrogen, progesterone, or HER2
- Triple positive, positive for estrogen receptors, progesterone receptors, and HER2
These classifications allow doctors to determine what types of treatments will work best.
About ~75% of all breast cancers are ER+, growing in response to the hormone estrogen. About 66% of these are also PR+, growing in response to a different hormone, progesterone. Cancers that are ER+ or PR+ are hormone receptor positive and are likely to respond to endocrine therapies, e.g. ER+/PR+ tumors are 60% likely to respond to endocrine therapy, while tumors that are ER-/PR- are only 5% to 10% likely to respond to endocrine therapy.
In ~20% of breast cancer cases, the cancer cells make too much of a protein called HER2/neu. These cancers tend to be much more aggressive, and fast growing, though the drug Herceptin has been shown to dramatically reduce the risk of recurrence when used with adjuvant (after surgery) chemotherapy.
Finally, a smaller proportion of breast cancers – estimates range between 10% and 19% – are known as “triple negative” because they lack estrogen and progesterone receptors and do not overexpress the HER2 protein. The majority of breast cancers associated with the breast cancer gene known as BRCA1 are triple negative. While triple negative cancers generally respond well to adjuvant chemotherapy, their prognosis is overall still poorer than that of other types of breast cancer, as no targeted therapies have been developed to help prevent recurrence.
I’d also like to take a moment to explain some statistical jargon for those ::cough:: 1Flesh ::cough:: who might not understand it.
AR = absolute risk.Absolute risk is risk stated without any context. These risks aren’t compared to any other risk; they’re just the probability of something occurring. For example, you have a 50% chance of flipping a coin and getting heads. They can be expressed as percentages, or ratios. As mentioned above, the absolute risk of a woman being diagnosed with breast cancer in the US is 1 in 8, or a 12.5% chance.
RR = relative risk.Relative risk is a comparison between different risk levels. For example, your relative risk for lung cancer is (approximately) 10 if you have ever smoked, compared to a nonsmoker. This means you are 10 times as likely to get lung cancer. It’s important to keep in mind that relative risk is not the same as an increase in risk. For example, the relative risk of smoking is a factor of ten, but this means that the increase is by a factor of nine, i.e. a 900% increase is the same as the relative risk of 10.
An important feature of relative risk (and one that will become very important in the discussion that follows) is that it tells you nothing about the actual risk. This is incredibly important for evaluating how significant a relative increase might be. A small increase of risk in a large population could result in many deaths; conversely even a large increase in a small risk population could result in very few deaths. Finally, remember that the comparison group is considered “1.” If the relative risk is “1”, this means that there is no increased risk.
CI = confidence interval. A confidence interval is an estimate range of values and is used to indicate the reliability of an estimate. For example, when you see RR, 1.24, 95% CI, 1.15-1.33, it means that the relative risk is 1.24 (or a 24% increase), and the researchers are 95% certain that the range of values truly fall between 1.15 and 1.33.
Now, on to fun part: dissecting 1Flesh’s claims.
Why? Because oral contraceptives cause a significantly higher rate of breast cell division, and in general, cells that divide more rapidly are more likely to become cancerous.
Using a medical study from 1989? Again with the outdated studies, 1Flesh. How about we look at something more recent, like information from the authors of the 2002 CARE study about what actually happens when hormones interact with breast cells:
Prior to menopause, levels of progesterone (the natural version of progestin) and estrogen in a woman’s body rise and fall over the course of her monthly cycle. Estrogen thickens the endometrium, then the ovaries release an egg. After ovulation, progesterone levels increase to prepare the uterus for pregnancy. If pregnancy does not happen, progesterone levels drop.
|Top set of graphs show normal cycle
Bottom set of graphs show OC usage
These hormones don’t just affect the uterus, however; they travel through the blood to breast and other tissues. Estrogen and progesterone stimulate breast cells to divide and multiply. And, as 1Flesh correctly states above (I know, I’m as shocked as you are), the more breast cells multiply, the greater the chance that genetically faulty cells (read: cancer causing cells) survive and multiply out of control.
According to Ursin, one of the study authors, “The greatest amount of division and proliferation of breast cells happens when estrogen and progesterone come together…at the end of the cycle. But something interesting happens with women taking oral contraceptives. In these women, the levels of breast cell proliferation remain almost level throughout the month.”
In other words, instead of having the highs and lows of estrogen and progesterone experienced by premenopausal women, women on OCs have more stable hormone levels as the pill “tricks” the body into not ovulating, and maintains a steady level of estrogen and progestin.
This means that the average amount of monthly hormones flowing through a woman taking OC and those not taking OC are about the same, with OC sometimes providing even LESS hormones. Even more importantly, by the end of a cycle, breast cells in a woman taking OCs have multiplied by as much as – or maybe even slightly less – than a woman not on OC.
Huzzah for learning about stuff, and for studies using more recent data!
By how much? According to the 2009 study Risk Factors for Triple-Negative Breast Cancer in Women Under the Age of 45 Years, published in the journal Cancer Epidemiology, Biomarkers, and Prevention, after less than one year of taking oral contraceptives, a woman’s risk of triple-negative breast cancer is increased 2.5 fold.
After more than one year of use, her risk is increased by 4.2 fold.
Half-truths again, you silly geese over at 1Flesh? This (outdated) study examined the risk association between oral contraceptive usage and triple-negative breast cancer (again, the rarest form of breast cancer) among women who were diagnosed between the ages of 20 and 45 between the years of 1983 and 1992. The actual results of this study are as follows:
Women in this cohort who used OCs for more than one year had a 2.5 fold increase in the risk of triple-negative breast cancer, with the risk of triple-negative breast cancer being higher for women under 40 years of age (a 4.2 odds ratio). However, there was NO significantly increased risk with OC use for non-triple-negative breast cancer among any women, nor for triple-negative breast cancer among women 41-45 years of age.
There we go. That’s better, right? Accuracy in reporting always helps.
Further, it should be noted that the study did not differentiate between various types of hormonal contraception, though it is likely that many of the women in the study (particularly those who had been taking the pill for longer periods of time, and who were more likely to suffer an increased risk) had been taking oral contraceptives containing much higher doses of hormones.
To explain, OC’s available to women in this study would have most likely been first generation (containing more than 35 micrograms of estrogen and more than 2.5 milligrams of progestin) or second generation (containing less than 35 mcg of estrogen and less than 2.5 mg of slightly newer progestins like norethindrone or levonorgestrel).
By contrast, today’s OCs contain even lower amount of estrogen (typically 20mcg to 30mcg) and much lower levels of newer progestins (from .15 mg of second generation progestins like levonorgestral to .18mg of third generation progestins like norgestimate).
As explained above, lower levels of hormones (particularly newer formulations of hormones) = lower levels of risk. And, actually, we have some data to back up that assertion:
The largest modern study, published in 2002, enrolled more than 4500 patients with breast cancer and 4500 controls aged 35 to 64 years from the United States from 1994 to 1998. Key findings from this study included no breast cancer risk among current (OR, 1.0; 95% CI, .8 – 1.3) or former (OR, 0.9; 95% CI, .8 – 1.0) OC users and no risks associated with duration of use or dose of estrogen. Moreover, a recent study of OC use in more than 4200 patients with breast cancer found no association between breast cancer mortality and OC use when duration of OC use, time since first use, age at first use, and use of specific formulations was examined. While breast cancer risks of the newest formulations of OCs are still unknown, based on the most recent data, they are predicted to show no association with the newest dosages and compositions of the estrogens and progestins being used.
Birth control’s link to breast cancer is seeming pretty damn tenuous at this point 1Flesh, but we’ll keep going.
Triple-negative breast cancer is a particularly aggressive subtype of breast cancer, with little treatment available outside of chemotherapy and mastectomy.
Ohemgee. A completely true sentence. Be still my heart! Yes, triple-negative breast cancer is a particularly aggressive subtype of breast cancer, for which treatment options are severely limited. HOWEVER, as noted above, this particular type of cancer is fairly rare – comprising only 10 – 19% of cases.
This risk is further increased if a woman begins her use of oral contraceptives before the age of 18, or if she smokes. This increased risk persists for 10 years after ending the use of the Pill.
Um, source? Because, sorry 1Flesh, I kind of think you’re pulling this info out of your ass. It’s definitely not listed in the study you just mentioned. For future reference, you can’t just pull bits and pieces out of various studies (or list completely inaccurate information) and claim one study said them all. Science doesn’t work that way.
While it is true that it is recommended that women taking OCs not smoke, particularly if they are 35 years of age or older, that fact was not mentioned in this study. And, actually, data from this study showed that smoking did NOT increase the risk for triple-negative-breast cancer. In addition, according to this study’s data, the risk for women who began taking OC’s before age 18 was heightened, but not “further increased” beyond the risks listed above. Again, accuracy matters, particularly when you’re playing with women’s health.
Also, the idea that increased risk persisted for 10 years after discontinuation was definitely not mentioned in this study, as they didn’t break the data down that way. It would be helpful if 1Flesh cited a source for this “fact.”
Actually, you know what, 1Flesh, here, I’ll help you. The data on OC use and increased risk for ten years prior to discontinuation comes from this study. First, it should be noted (again) that this study was a meta-analysis of 54 previous studies, most of which involved women using early generations of OCs containing higher levels of hormones. Second, the results of the study are far from damning:
[W]hile women are taking combined oral contraceptives and in the 10 years after stopping there is a small increase in the relative risk of having breast cancer diagnosed (relative risk [95 percent CI] in current users 1.24 [1.15-1.33], 2p<0.00001; 1-4 years after stopping 1.16 [1.08-1.23], 2p=0.00001; 5-9 years after stopping 1.07 [1.02-1.13], 2p=0.009). Second, there is no significant excess risk of having breast cancer diagnosed 10 or more years after stopping use (relative risk 1.01 [0.96-1.05], NS).
In layman’s terms, this means that even using data on OCs with extremely high levels of hormones, the increased risk of breast cancer was only 24% for current users, dropping to 16% in years 1-4 after discontinuation, to 7% in years 5-9 after discontinuation, and finally dropping to no increased risk at year ten and beyond.
See how easy that was to back up my statement, 1Flesh? I’d encourage you to look into that in the future.
This study has been validated by subsequent studies such as the 2010 study Oral Contraceptive Use and Estrogen/Progesterone Receptor–Negative Breast Cancer among African American Women published in Cancer Epidemiology, Biomarkers, and Prevention.
|Skeptical kid is skeptical.|
Forgive me, but how exactly does a study about a completely different type of cancer validate a previous study? In case 1Flesh wasn’t paying attention, the previous study found a small link between women under 45 diagnosed with breast cancer between 1983 and 1992 who had taken some form of oral contraception for more than a year, and triple-negative breast cancer. That study also found no increased risk for non-triple-negative breast cancer for women under 40, and no increased risk for any type of breast cancer for women aged 41 – 45.
Yeah, this study totes does NOT “validate” the previous study. But let’s look at it anyway, shall we?
This specific study looked at the possible link between recent formulations of oral contraceptives and the risk of ER- (that is, double negative) breast cancer in African-American women SPECIFICALLY. The study found a slightly increased risk of ER- breast cancer in African-American women (RR 1.65, 95% CI, 1.19 – 2.30), and a 2.5 fold increase for those who had taken oral contraceptives for more than 10 years. However, the researchers also stated that, “Because the prevalence of oral-contraceptive use is similar or perhaps even lower among African-American women than white women, oral-contraceptive use by itself is unlikely to explain the higher proportion of ER− breast cancers among African-American women.”
And again, this is a rather rare form of breast cancer. If you’re having to look for data on the rarer forms of breast cancer instead of for data on the types of breast cancer that the majority of American women are facing to make your claim (and are still kind of failing….), you’re doin’ it wrong.
It is entirely likely — though currently unproven — that the massive increase in breast cancer cases around the world since the 1970′s has been caused by the likewise massive increase in the use of oral contraception, and its subsequent effects on the environment.
Key words in that paragraph? “Though currently unproven.” I’d change that to won’t be proven, but otherwise, yes, there HAS been a massive increase in breast cancer cases.
And you know what’s also interesting? We have proven causes for this, even hormonal ones. Want to hear a few
- Improved nutrition globally means that girls are reaching puberty earlier, and women are reaching menopause later, exposing women to more estrogen than before. A century ago, girls had their first periods at 16 or 17; today the average age is closer to 12 or 13. When first menarche occurs before age 12, or menopause occurs after age 55, the risk of breast cancer is increased.
- Family-unfriendly policies in the nation’s workforce have led to later births, smaller families, later age at first birth, and fewer women breastfeeding, all of which have been shown to increase the risk of breast cancer.
As for the effect of OCs on the environment, sorry 1Flesh, but that theory’s been thoroughly debunked by others. Try harder.
Adding further support to this research, The International Agency for Research on Cancer (IARC) lists combined oral contraceptives as Group 1 carcinogens. ‘Group 1’ includes carcinogens in which “the agent (mixture) is definitely carcinogenic to humans.” Other Group 1 carcinogens include asbestos, mustard gas, ultraviolet radiation, and formaldehyde.
Please take note that the IARC also asks us to take note that there is convincing evidence in humans that OC’s confer a protective effect against cancer of the endometrium and ovary.
You know what else is categorized as a Group 1 carcinogen? Alcoholic drinks, wood dust, oh, and the sun (among about about 99 other things). Also, not to be picky (oh, hell, who am I kidding, yes, to be picky), the preamble for the IARC lists contains the REAL definition for when items are to be placed in Group 1, and it’s this:
This category is used when there is sufficient evidence of carcinogenicity in humans. Exceptionally, an agent may be placed in this category when evidence of carcinogenicity in humans is less than sufficient but there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent acts through a relevant mechanism of carcinogenicity.
Ever so slightly different, but enough to matter to those of us concerned with accuracy.
It’s true that the Pill reduces the risk of other cancers, most notably ovarian cancer. However, a woman’s lifetime risk of breast cancer is 12%, while her risk for ovarian cancer is only 1.38%. The Pill increases her risk of the former by 4.2 after just 1 year, and only decreases a woman’s risk of ovarian cancer by half after 10 years of use. Not worth it.
Oh goodie! Now we get to the part where I get to talk about all of the completely awesome things about OCs!
First, I just have to mention this because it’s just THAT amazingly cool. Two recent studies, including on ongoing study following 45,000 women for up to 39 years and a completed study including 17,000 women followed through 2009 both found that ever use of OCs resulted in a lower relative risk of mortality (RR .88, CI 95%, .82-.93 and RR, .87, CI 95%, .79 – .96). If you’ve been following along with all this statistics mumbo jumbo, you’ll realize that that means that women who have ever used oral contraceptives have a 12-13% lower relative risk of mortality than women who have never used OC. Now we ALL know that correlation is not causation, but that’s still pretty freaking cool, is it not?
I could talk about lots of other awesome things about OCs, but since 1Flesh chose specifically to talk about cancers in this post, that’s what I’ll talk about here, too.
1Flesh is right (I know, twice in one post? I feel faint) in that a woman’s lifetime risk of developing breast cancer being 12%. And they’re only slightly wrong about the lifetime risk of ovarian cancer (it’s actually 1.42%). But that’s where we part ways on this one.
We’ve already talked about how the 4.2 fold increased risk is bunk, as it only applies to triple-negative-breast cancer for women under age 40 who were most likely using older generation OCs which might higher hormone levels, so I won’t go into that again. What I will take issue with, however, is 1Flesh’s reporting half-truths, once again. The study 1Flesh cites clearly states (even in just the abstract) that:
The overall estimated protection from cohort and case-control studies is approximately 30% for ever OC users, and increases with duration of use by approximately 5% per year of use to about 50% for long-term (≥10 years) users. The favourable effect of OC against ovarian cancer risk persists for at least 20 years after OC use has ceased, and it is not confined to any particular type of OC formulation. The reduced risk among OC users is observed in women without or with family history or genetic predisposition to ovarian cancer, and for most histological types of epithelial ovarian cancer, although the pattern of risk is less consistent for mucinous than for other types. The protection of OC on ovarian cancer risk, also in view of its long-term persistence, corresponds to the avoidance of 3000-5000 ovarian cancers (and 2000-3000 deaths) per year in Europe, and a similar figure in North America.
That makes OC sound a hell of a lot better at preventing ovarian cancer, doesn’t it? See what a little honest reporting can do?
Further, oral contraceptives have also been found to have significant positive effects in preventing endometrial cancer. For instance, studies have found the risk of endometrial cancer to be 30 to 50% less among OC users than non-users.
Oh, and lest we forget about colorectal cancer, note that a meta-analysis of 11 controlled studies and 7 cohort studies found a RR of .81 (CI 95%, .72-.92) in OC users compared to never users, with the reduction in risk being greatest among recent users.
Finally, as we’ve spent much of this blog talking about breast tissue, now might be a good time to mention that current users of OC’s have at least a modest reduction in the risk of benign breast disease (which can potentially progress to cancer).
Still not worth it, 1Flesh?
These are the facts.
Well, NOW there are some facts thrown in there.
We at 1Flesh beg that pharmaceutical companies clearly label their oral contraceptive products as increasing breast cancer risk. We beg that pharmaceutical companies inform doctors of the risks contained in the pills advertised to them. We beg that doctors inform their patients of the risk of breast cancer conferred by their prescriptions.
And I beg that pharmaceutical companies clearly label their oral contraceptive products with correct information, i.e. that their products do NOT increase breast cancer risk. I beg that pharmaceutical companies inform doctors that their oral contraceptive products do not carry an increased risk of breast cancer, but do carry the benefits of preventing certain other types of cancers. And I beg that doctors inform patients of the truth of the risk between the use of oral contraceptives and breast cancer – namely that the risk does not exist.
We beg women to consider natural and more effective alternatives to carcinogenic birth control.
AND…again with the pitch to a form of natural family planning that isn’t really all that effective. But now I get it. Dr. Creighton has an honorary degree from the Franciscan University of Steubenville, where several of the founders of 1Flesh are currently students, and where the Creighton Model is taught as part of a premarital counseling program. Sometimes it’s easiest to promote what you know…even when what you know isn’t always the best.
Till next time,