Study Shows Link Between Antibiotic Use and Increased Risk of Breast Cancer
A study published today in the Journal of the American Medical Association (JAMA)* provides evidence that use of antibiotics is associated with an increased risk of breast cancer. The authors - from Group Health Cooperative (GHC) in Seattle; the National Cancer Institute (NCI), a part of the National Institutes of Health in Bethesda, Md.; the University of Washington, Seattle; and the Fred Hutchinson Cancer Center, also in Seattle - concluded that the more antibiotics the women in the study used, the higher their risk of breast cancer.
The results of this study do not mean that antibiotics cause breast cancer. "These results only show that there is an association between the two," explained co-author Stephen H. Taplin, M.D., of NCI's Division of Cancer Control and Population Sciences and formerly of the GHC. "More studies must be conducted to determine whether there is indeed a direct cause-and-effect relationship."
"This trial suggests another piece in the puzzle of factors that may potentially be involved in the development of breast cancer," said NCI Director Andrew C. von Eschenbach, M.D. "The NCI will continue to support research into underlying mechanisms of cancer risk."
The authors of this JAMA study found that women who took antibiotics for more than 500 days - or had more than 25 prescriptions - over an average period of 17 years had more than twice the risk of breast cancer as women who had not taken any antibiotics. The risk was smaller for women who took antibiotics for fewer days. However, even women who had between one and 25 prescriptions over an average period of 17 years had an increased risk; they were about 1.5 times more likely to be diagnosed with breast cancer than women who didn't take any antibiotics. The authors found an increased risk in all classes of antibiotics that they studied.
"Breast cancer is the second leading cause of cancer deaths among women in the United States - with an estimated 40,000 deaths this year - and is the most common cancer in women worldwide," said first author Christine Velicer, Ph.D., of GHC's Center for Health Studies. "Antibiotics are used extensively in this country and in many parts of the world. The possible association between breast cancer and antibiotic use was important to examine."
To gather the necessary data, the researchers used computerized pharmacy and breast cancer screening databases at GHC, a large, non-profit health plan in Washington state. They compared the antibiotic use of 2,266 women with breast cancer to similar information from 7,953 women without breast cancer. All the women in the study were age 20 and older, and the researchers examined a wide variety of the most frequently prescribed antibiotic medications.
The authors offer a few possible explanations for the observed association between antibiotic use and increased breast cancer risk. Antibiotics can affect bacteria in the intestine, which may impact how certain foods that might prevent cancer are broken down in the body. Another hypothesis focuses on antibiotics' effects on the body's immune response and response to inflammation, which could also be related to the development of cancer. It is also possible that the underlying conditions that led to the antibiotics prescriptions caused the increased risk, or that a weakened immune system - either alone, or in combination with the use of antibiotics - is the cause of this association.
The results of the study are consistent with an earlier Finnish study of almost 10,000 women. "Further studies must be conducted, though, for us to know why we see this increased risk and the full implications of these findings," said Velicer. Studies are also necessary to clarify whether specific indications for antibiotic use, such as respiratory infection or urinary tract infection, or times of use, such as adolescence, pregnancy or menopause, are associated with increased breast cancer risk. Additionally, breast cancer risks could differ between women who take low-dose antibiotics for a long period of time and women who take high-dose antibiotics only once in a while.
Antibiotics are regularly prescribed for conditions such as respiratory infections, acne, and urinary tract infections, in addition to a wide range of other conditions or illnesses. In this JAMA study, for example, more than 70 percent of women had used between one and 25 prescriptions for antibiotics to treat various conditions over an average 17-year period, and only 18 percent of women in the study had not filled any antibiotic prescriptions during their enrollment in the health plan.
Over the past decade, overuse of antibiotics has become a serious problem. According to the Centers for Disease Control and Prevention (CDC), tens of millions of antibiotics are prescribed for viral infections that are not treatable with antibiotics, contributing to the troubling growth of antibiotic resistance. Efforts are underway such as the "Get Smart: Know When Antibiotics Work" campaign - unveiled last year by the Department of Health and Human Services' CDC and the Food and Drug Administration (FDA) and other partners - to lower the rate of antibiotic overuse.
"These study results do not mean that women should stop using antibiotics to treat bacterial infections," stressed Taplin. "Until we understand more about the association between antibiotics and cancer, people should take into account the substantial benefits that antibiotics can have, but should continue to use these medicines wisely."
Questions and Answers about this study can be found at http://www.cancer.gov/newscenter/pressreleases/AntibioticsQa ndA.
I thought that after that study was released that there were many flaws found in the research methodology? It came out a few years back.Jasmine,
I looked for the flaws and couldn't find anything. A friend of mine sent this to me as she is concerned because she has used so many antibiotics and b/c runs in her family so if you can find where someone of authority has found flaws in the study, please let me know so that i can let her know, thanks.
LEV
Often studies have been wrong at first. Did for example these women ever take hormone pills? What other things might they have in coman? It is possible, anything is possible. My aunts husband is strictly against antibiotics unless of course you are dieing. She has breast cancer, but had taken hormone pills. He has angent orange and is diebetic and about to loose his legs. Genetics, high fat diet, hormones. Just a large number of things to cross section. The great thing in the fight against breast cancer is the newer ultra sound machines. They can pick up things smaller than a bb. Things that don't show up on mamogram. I will keep this info in mind but is it all antibiotics or just some?This study was in 2004 and I can still find the same warnings in 2007 but i haven't been able to find anything that has suggested that the study was flawed. This is all the information i could find. Early detection is good but let's hope for a cure.
Just curious, i wonder if women with implants are more or less susseptible to b/c. I know that smaller breasted women are less likely to get b/c. I think i would rather have small breasts rather than something foriegn inserted into my body but that just my male input. I don't think i would like my lady to have fake breasts. I guess vanity is in us all to an extent.
LEV
LevLarry -
This was an exceedlingly flawed study. I've posted about this before. Because it's Halloween and I have to take the little Vampire out, I'm reposting my original post about this study. Please take a good look at paragraph 8. They were looking at Minocin in particular - and the study sank! LOL
------------------------------
Lynn,
Unfortunately, there is validity to any medical study out there. That is why I try to search for researcher connections to Big Pharma - just trying to see what may be coloring the researchers vision. This study seems to be 'clean' by my standards (scientist that I am ;-) because it was run without interference by the NIC
When you posted the link to Pharmacist.com it gave a link to the JAMA article - which of course gave a lot more info than the blurb.
In reading the study I noticed under results: Items I want to highlight from the study is in blue - my snarky commentary is in fushia.
Cases and controls were similar with respect to age, race, length of GHC enrollment with computerized pharmacy data available, pharmacy co-payment status, parity, hysterectomy status, age at menopause, and ever use of postmenopausal hormones (Table 1). A larger proportion of cases than controls were educated beyond high school, had a higher number of health care visits, were premenopausal, had ever used oral contraceptives, and had filled more than 25 postmenopausal hormone prescriptions. Cases were also more likely than controls to have menarche before age 11, first birth after age 30 years, higher body mass index, a first-degree family history of breast cancer, and higher mammographic breast density. As shown in Table 2, in control participants, increasing cumulative number of prescriptions was associated with older age, white race, longer length of enrollment at GHC, increasing number of health care visits, pharmacy co-payment greater than , age at menarche younger than 11 years, higher body mass index, family history of breast cancer, prior hysterectomy, generally younger age at menopause, ever use of postmenopausal hormones, and higher number of postmenopausal hormone prescriptions. In control participants, both never users and high users of antibiotics were more likely to be postmenopausal than were women with low levels of use. Among breast cancer cases, increasing cumulative number of prescriptions was associated with older age, longer length of enrollment at GHC, increasing number of health care visits, parity, higher body mass index, prior hysterectomy, ever use of postmenopausal hormones, and higher number of postmenopausal hormone prescriptions (Table 2).
Please note they were not comparing apple to apples. The 'cases' had a lot more prescriptions (gee, any AI diseases in there?) etc. I mean everything was not similar from age at mense to number of visits.
Also note: the 2X increase in breast cancer is for women who took over 25 courses of ABX over 17 years! 17 years! And women who took between 1 and 25 courses of ABX in the same time frame (17 years) had a 1.5 increase in BC). So - let me get this right - take ABX ONE TIME in your life and you have almost the same chance of getting BC than a person who took multiple doses???? These guys were stretching here!
Also, under the 'comment' section there was a lot of explaining how they couldn't account for a lot of stuff.
In a subset of study participants with heavy use of macrolide and tetracycline antibiotics, we found no difference in risk of incident breast cancer among women using these antibiotics for acne and/or rosacea (gee, AP is less antibiotics than for acne.) compared with women using these drugs for respiratory tract infections. Because the severity of acne and rosacea can be related to levels of estrogen, unlike most respiratory tract infections, we reasoned that this indication for long-term antibiotic use might be associated with an increased risk of breast cancer. Our results did not support this hypothesis (well, we thought that would be the case but our study tanked on that issue but really, it's not our fault because we had 'limited power' meaning - we don't have enough info to make a strong case) but our study had limited power; the number of women included in the subset was small and the CI was wide. Additional studies (they all say 'additional studies are needed) are needed to further clarify whether indication for antibiotic use is associated with risk of breast cancer. So, basically, we don't know if ABX uses is associated with breast cancer - but hot damn! it made a good blurb on the evening news, didn't it!
The hypothesis that some classes of antibiotics may increase risk of breast cancer is plausible; antibiotics have effects on intestinal microflora and on immune and inflammatory responses.2 (now this makes a hell of a lot of sense) For example, antibiotic use may increase risk of breast cancer by decreasing phytochemical metabolism by intestinal microflora.4, 16 Phytochemicals are hypothesized to play an inhibitory role at several points in the carcinogenesis pathway by modulating enzymes involved in carcinogen and steroid hormone metabolism. (Will everybody PLEASE start taking probiotics even if you don't do AP - he's saying here that there is a hypothesis that says probiotics MAY STOP cancer from starting)16-19 Also, use of tetracycline may be associated with increased production of prostaglandin E2, a hallmark of the inflammatory response, catalyzed by cyclooxygenase 1 and 2.20 (Here he's saying it's associated with inflammation - gee - we're AI, OF COURSE we have inflammation - oh wait, inflammation GOES AWAY on AP - is he talking about a herx???). Overexpression of cyclooxygenase 2 is associated with mammary carcinogenesis, while inhibition of prostaglandins and other inflammatory responses by nonsteroidal anti-inflammatory drugs is associated with a 20% to 40% decreased risk of breast cancer. Here he's saying taking NSAID's cuts inflammation and leads to a 20-40% DECREASED risk of Breast Cancer. 21-24 Although this evidence suggests that antibiotics may be associated with breast cancer, it is also possible that a weakened immune system (either alone (I'm guessing alone) or in conjunction with use of antibiotics) is the biologically relevant basis of this association. Duh!
The strengths of this observational study include the use of population-based cases and controls, the identification and validation of case diagnoses through the Surveillance, Epidemiology, and End Results registry, the ability to include all participants because no direct participant involvement was required, and the use of the GHC pharmacy database to assess antibiotic use in an unbiased manner for cases and controls. Our method of measuring antibiotic use did not capture data for inpatient antibiotic use or antibiotics purchased outside GHC, and could not determine whether prescriptions dispensed were actually used. However, we have no reason to suspect differences between cases and controls, and therefore if any bias exists because of misclassification of antibiotic exposure, we would expect that the current results are biased toward the null. This is saying 'any missing info would push our theory more towards no relationship.
We had missing data for some of the known or suspected risk factors for breast cancer shown in Table 1, and no information for other potential risk factors, such as alcohol use and lactation. Whether this missing information is problematic is difficult to determine; it may have limited our ability to detect confounding. Also, at the highest levels of antibiotic exposure, sample sizes were small and CIs were wide; however, the confidence limits consistently excluded 1. We have some assurance that antibiotic use is not simply a proxy for health care–seeking or mammography-detection bias; the association between cumulative days of antibiotic use and fatal breast cancer was similar to that for the association with incident breast cancer, similar BC for fatal and just 'regular' BC and number of health care visits did not confound (screw up) the association between use of antibiotics and incident breast cancer.
Given that we found an association using relatively straightforward measures of antibiotic use, more detailed analyses including timing of exposure and considering various antibiotic doses might further clarify this association. For example, the amount of antibiotic use at particularly sensitive times in breast development, such as adolescence, pregnancy, or during menopause, may be pertinent. You think??? We were unable to conduct such analyses because there were relatively few women with pharmacy records covering the time span from adolescence or childbearing years through postmenopause. Additionally, it is possible that risks of breast cancer differ between women with long-term use of low-dose antibiotics and those with intermittent use of higher-dose antibiotics. Certainly does if recent research linking mycoplasmas to breast cancer is right.
In summary, we found that increased use of antibiotics was associated with increased risk of incident and fatal breast cancer for a variety of antibiotic classes. It cannot be determined from this study whether the use of antibiotics is causally related to breast cancer, or whether the indication for antibiotic use, overall weakened immune function, or other factors are the pertinent underlying exposures. (Yeah, yeah, more studies are needed). While the implications for clinical practice will not be clear until additional studies are conducted, the results of this study support the continued need for prudent long-term use of antibiotics and the need for further studies of the association between antibiotic use and cancer risk.
This studies are much more applicable.
This says Doxy is an "Efficient treatment of Mycoplasma hyorhinis contamination in MCF-7 breast cancer cells with doxycyclin"
Also, I haven't verified any of the info in this article and don't know who this guy is - but there are some interesting links to cancer and ABX - especially lymphoma (which we are all supposedly at risk for with RA).
http://ezinearticles.com/?Do-Bacteria-Cause-Cancer?&id=6 41484
Lynn, how is this weak and faulty study applicable here? The questions remain. Do biologics weaken an already weakened immune system to the point that another disease pops up? Is it the start of an AI cascade? Again - on AP the MIL goes away. Why doesn't another AI disease do that on the biologics?
Pip
Well i have to take more antibiotics so i did not want to here this today. With cipro you could get toxic levels and i have to take more than 10 days. So just bad timing on my part. I have to think to my advantage you know. Try to keep positive. I think they use saline instead of silicone now a days. I don't know. Mine are real so i don't investigate alot. I do know silicone can cause fibromyagia. Or a court awarded alot of money to alot of women with implants for having gotten fibromyalgia. Several years ago. Used to use silicone spray on the press machines at work. It said it could cause cancer in california. I guess california was the only place that cared. We were in Ill but found that very concerning.Lev -
Did you have any comments?
Pip