Coffee, black tea possibly protective against nonmelanoma skin cancer
Caffeinated drinks, such as coffee and black tea, may protect against nonmelanoma skin cancer (NMSC) among Chinese in Singapore, according to a recent study.
“In this large prospective cohort of middle-aged and elderly Chinese, we found that those who consumed coffee or black tea daily had a reduced risk of developing NMSC,” said researchers. “Specifically, coffee drinking was associated with reduced risk of both [basal cell carcinoma (BCC)] and [squamous cell carcinoma (SCC)], whereas daily tea drinking reduced the risk of BCC.”
Drawing from the Singapore Chinese Health Study (n=61,321; mean age, 56.4±8.0 years; 55 percent female), researchers identified 427 and 182 incident cases of BCC and SCC, respectively, over a mean follow-up of 18.3±5.7 years. Males accounted for 48.3 percent of all cases; mean age at skin cancer diagnosis was 74.3±8.9 years. [J Am Acad Dermatol 2019;81:395-402]
Majority (70.4 percent) of the study population drank coffee every day, while 11.2 percent reported consumption of black tea with the same frequency. A daily green tea habit was observed in 12.4 percent. Sodas, in comparison, were less popular, with only 4.3 percent of the participants reporting intake of ≥3 times per week.
Coffee had a significant and dose-dependent protective effect against NMSC risk. For instance, those who drank 1–2 cups per day were significantly less likely to develop the disease than those with less than a weekly frequency of consumption (hazard ratio [HR], 0.74, 95 percent CI, 0.61–0.89).
This effect was more pronounced in participants who drank ≥3 cups per day (HR, 0.47, 0.29–0.75), such that the trend was statistically significant (p=0.0001).
A similar effect was observed for black tea, though to a lesser degree. Only those with daily consumption enjoyed significant protection relative to nondrinkers (HR, 0.70, 0.52–0.94; p-trend=0.015). No such effects were observed for green tea (p-trend=0.42) and soda (p-trend=0.89).
Disaggregating according to NMSC subtype, researchers found that coffee was significantly protective against both BCC (vs nondrinkers; ≥3 cups per day: HR, 0.54, 0.31–0.93; 1–2 cups per day: HR 0.78, 0.62–0.98; p-trend=0.017) and SCC (≥3 cups per day: HR, 0.33, 0.13–0.85; 1–2 cups per day: HR, 0.64, 0.45–0.91; p-trend=0.001).
Black tea, on the other hand, was only effective against BCC (vs nondrinkers; daily: HR, 0.74, 0.52–1.04; weekly to <daily: HR, 0.69, 0.51–0.93; p-trend=0.01), but not against SCC (p-trend=0.57).
“To our best knowledge, this is the first prospective study to show an inverse association between coffee or caffeine and risk of SCC, which contradicts the largely null associations from previous studies,” said researchers.
Several important limitations are worth considering, they continued. Among these are the measurement of caffeine intake at baseline, failure to account for possible decaffeinated beverages, and the shortage of data on other potential confounders, such as family history, chemical exposure or outdoor sun exposure.
“We hope that our study can provide the impetus for further research to determine which component(s) of coffee and tea are responsible for the chemoprotective effect and whether caffeine is indeed the agent responsible for this effect,” researchers added.