Surely, it's no coincidence that a tasty, warming mood-elevator like coffee's so popular in places like Seattle and Stockholm – home to Starbucks and Gavelia – where sun is in short supply.
Fortunately for all other java junkies, drinking coffee doesn't seem to raise the risk of any kind of cancer consistently or significantly … judging by the considerable evidence collected so far.
Albeit generally positive, the evidence to date on the beverage's possible connections to breast cancer risk has been mixed.
Some studies suggest a lower risk among women who love coffee … but others found no benefits (Bhoo Pathy N et al. 2009; Nilsson LM et al. 2010; Arab L. 2010; Yu X et al. 2011; Fagherazzi Get al. 2011).
Coffee: A healthful indulgence?
Overall, coffee seems to be a benign-to-beneficial habit.
For example, moderate caffeine intake enhances concentration and focus … without, despite common but unfounded claims, taxing the adrenal glands.
Better yet, coffee is the average Americans' top source of beneficial polyphenol “antioxidants” … beating all other plant food and beverages combined.
While this exalted status stems from the dominance of refined, polyphenol-poor plant foods in the standard American diet, there's no doubt that coffee is extraordinarily rich in healthful polyphenols.
And it's pretty clear that coffee helps deter diabetes, as Dutch scientists reported six years ago:
“This systematic review supports the hypothesis that habitual coffee consumption is associated with a substantially lower risk of type 2 diabetes.” (van Dam RM et al. 2005)
What about heart health?
Last year, Chinese researchers who examined the evidence concluded, “Our findings do not support the hypothesis that coffee consumption increases the long-term risk of coronary heart disease.” (Wu JN et al. 2010)
Adding more reassurance, a recent evidence review found that coffee doesn't cause chronic high blood pressure (hypertension) to any significant extent (Zhang Z et al. 2011).
Coffee-drinking is also linked to reduced rates of Parkinson's disease, certain cancers, and suicide.
Increases in “silent”, non-symptomatic inflammation might be a concern, with some evidence suggesting that coffee causes them.
On the other hand, coffee is loaded with polyphenols believed to exert effects that curb inflammation by indirect, “nutrigenomic” influences over gene expression, so coffee may be a “wash” in terms of inflammation.
Now there's encouraging epidemiological evidence from Sweden indicating that women who drink coffee copiously may be at lower risk of breast cancer … especially the least treatable, “ER-negative” kinds.
Before we examine the new research, it'll help to understand that basic distinction between cancers of the breast.
A quick estrogen/cancer primer
Breast cancers are divided into two major classes, depending on whether they have estrogen receptors (ER-positive) or lack them (ER-negative).
ER-negative tumors have historically had a poorer prognosis and fewer prevention and treatment strategies, compared to ER-positive tumors, although some treatments show promise (Putti TC et al. 2005).
About one-third of all breast cancers involve ER-negative tumors, while some 15 percent are triple-negative cancers, whose cells lack receptors for any of the three potentially cancer-fueling hormones: estrogen (ER), progesterone (PR), and human epidermal growth factor.
Coincidentally, researcher just reported finding a link between higher vitamin D blood levels and lower risk of triple-negative tumors … see “Vitamin D Lack Linked to Toughest Breast Tumors”.)
Heavy coffee habit linked to lower risk of tough, “estrogen-negative” tumors
Researchers from Sweden's Karolinska Institute just published the results of an epidemiological “case-control” study among 5,924 women … 2,818 who had breast cancer, and 3,111 healthy controls.
Accounting for other risk factors, their analysis linked drinking five cups of coffee or more daily to a 20 percent drop in the overall risk of breast cancer.
Better yet, women who drank five cups of coffee or more daily were 57 percent less likely to have the tougher-to-treat “ER-negative” tumors..
Needless to say, it makes little sense to start quaffing that much coffee just to curb the risk of breast cancer.
Instead, these findings simply constitute more evidence that coffee may help curb breast cancer … and that copious consumption may help deter the worst kinds.
Arab L. Epidemiologic evidence on coffee and cancer. Nutr Cancer. 2010;62(3):271-83. Review.
Bhoo Pathy N, Peeters P, van Gils C, Beulens JW, van der Graaf Y, Bueno-de-Mesquita B, Bulgiba A, Uiterwaal CS. Coffee and tea intake and risk of breast cancer. Breast Cancer Res Treat. 2010 Jun;121(2):461-7. Epub 2009 Oct 22.
Fagherazzi G, Touillaud MS, Boutron-Ruault MC, Clavel-Chapelon F, Romieu I. No association between coffee, tea or caffeine consumption and breast cancer risk in a prospective cohort study. Public Health Nutr. 2011 Apr 5:1-6. [Epub ahead of print]
Li J et al. Coffee consumption modifies risk of estrogen-receptor negative breast cancer.Breast Cancer Research. May 11, 2011. 13:R49doi:10.1186/bcr2879. Accessed at http://breast-cancer-research.com/content/13/3/R49
Nilsson LM, Johansson I, Lenner P, Lindahl B, Van Guelpen B. Consumption of filtered and boiled coffee and the risk of incident cancer: a prospective cohort study. Cancer Causes Control. 2010 Oct;21(10):1533-44. Epub 2010 May 30.
Putti TC, El-Rehim DM, Rakha EA, Paish CE, Lee AH, Pinder SE, Ellis IO. Estrogen receptor-negative breast carcinomas: a review of morphology and immunophenotypical analysis. Mod Pathol. 2005 Jan;18(1):26-35.
van Dam RM, Hu FB. Coffee consumption and risk of type 2 diabetes: a systematic review. JAMA. 2005 Jul 6;294(1):97-104. Review.
Wu JN, Ho SC, Zhou C, Ling WH, Chen WQ, Wang CL, Chen YM. Coffee consumption and risk of coronary heart diseases: a meta-analysis of 21 prospective cohort studies. Int J Cardiol. 2009 Nov 12;137(3):216-25. Epub 2008 Aug 15.
Yu X, Bao Z, Zou J, Dong J. Coffee consumption and risk of cancers: a meta-analysis of cohort studies. BMC Cancer. 2011 Mar 15;11:96.
Zhang Z, Hu G, Caballero B, Appel L, Chen L. Habitual coffee consumption and risk of hypertension: a systematic review and meta-analysis of prospective observational studies. Am J Clin Nutr. 2011 Mar 30. [Epub ahead of print]