Coffee Linked to Cancer
Based on the results of a study examining coffee and lung cancer, you may want to think twice about pouring that second cup o’ joe.
The study results were presented March 31 at the American Association for Cancer Research. It concluded: (1)
High consumption of coffee or tea was both associated with an increased risk of lung cancer regardless of race or smoking status. Our study included a large number of never-smoker lung cancer patients, which minimized potential confounding effects due to smoking. The positive association observed for both caffeinated and decaffeinated coffee suggests that compounds other than caffeine may play a role in the etiology of lung cancer.
An international group of researchers, including study author Jingjing Zhu, a Ph.D. student at Vanderbilt, analyzed data from 17 different studies that included a total of 1.2 million participants in the U.S. and Asia. The reviews noted whether participants drank coffee or tea or smoked cigarettes. About half were nonsmokers.
The participants were tracked for an average of 8.6 years. During that time, more than 20,500 participants developed lung cancer.
The researchers found that nonsmokers who drank two or more cups of coffee a day had a 41 percent higher risk of lung cancer than those who didn’t drink coffee. Similarly, nonsmokers who drank two or more cups of tea a day had a 37 percent greater risk of lung cancer than non-tea drinkers. (Because data was taken from multiple studies, the exact definition of a cup varied.)
The study also found that a person’s risk didn’t change significantly between ages, races or the type of coffee people drank — both decaf and caffeinated coffee seemed to be associated with similar risks. In fact, decaf coffee was associated with a 15 percent higher risk than caffeinated coffee, Zhu said. (2)
Still, Zhu noted that “this [was] only an observational study” and didn’t prove cause-and-effect. But the researchers hypothesize that it isn’t caffeine that’s behind the link. Instead, it may be that something in the roasting process is driving the relationship between coffee and lung cancer risk, Zhu told Live Science.
Lung cancer rates falling
The American Cancer Society estimates 228,150 new cases of lung cancer will be diagnosed in the U.S. in 2019. An estimated 142,670 deaths from lung cancer will occur this year. (3)
The incidence rate for lung cancer has been declining since the mid-1980s in men, but only since the mid-2000s in women because of gender differences in historical patterns of smoking uptake and cessation. The decline has gained momentum in the past decade, with rates decreasing from 2011 to 2015 by almost 3% per year in men and 1.5% per year in women.
The lung cancer death rate has declined by 48% since 1990 in men and by 23% since 2002 in women due to reductions in smoking, with the pace accelerating in recent years consistent with incidence trends; from 2012 to 2016, the rate decreased by about 4% per year in men and 3% per year in women.
Cigarette smoking is by far the most critical risk factor for lung cancer; 81% of lung cancer deaths in the U.S. are still caused by smoking. Risk increases with both the quantity and duration of smoking. Cigar and pipe smoking also increase risk.
Exposure to radon gas, which is released from soil and can accumulate in indoor air, is thought to be the second leading cause of lung cancer in the US. Other risk factors include exposure to secondhand smoke, asbestos (particularly among smokers), certain metals (chromium, cadmium, arsenic), some organic chemicals, radiation, air pollution, and diesel exhaust.
Specific occupational exposures that increase risk include rubber manufacturing, paving, roofing, painting, and chimney sweeping.
Symptoms and treatments
Symptoms include persistent cough, sputum streaked with blood, chest pain, voice change, worsening shortness of breath, and recurrent pneumonia or bronchitis. Symptoms usually do not appear until the cancer is advanced.
Appropriate treatment for lung cancer is based on whether the tumor is small cell (13%) or non-small cell (84%), as well as the stage and molecular characteristics. For early-stage non-small cell lung cancer, surgery is the usual treatment, sometimes with chemotherapy, alone or in combination with radiation therapy. Advanced-stage non-small cell lung cancer is usually treated with chemotherapy, targeted drugs (or a combination of the two), or immunotherapy. Small cell lung cancer is generally treated with chemotherapy, alone or combined with radiation; a large percentage of patients on this regimen briefly experience remission, although the disease often returns.
The 5-year relative survival rate for lung cancer is 19% (16% for men and 22% for women) and is higher for non-small cell (23%) than small cell tumors (6%). Only 16% of lung cancers are diagnosed at a localized stage, for which the 5-year survival rate is 56%.
(1) Jingjing Zhu, et. al. Associations of coffee and tea consumption with lung cancer risk: A pooled analysis of 17 cohort studies involving over 1.2 million participants. https://www.abstractsonline.com/pp8/#!/6812/presentation/1822
(2) Yasemin Saplakoglu. There May Be a Link Between Coffee and Lung Cancer, Study Suggests. https://www.livescience.com/65136-coffee-lung-cancer.html
(3) Cancer Facts & Figures 2019. American Cancer Society. https://www.cancer.org/research/cancer-facts-statistics/all-cancer-facts-figures/cancer-facts-figures-2019.html