Master of Public Health Marko Lukic disputerer for ph.d.-graden i helsevitenskap og vil offentlig forsvare avhandlingen:
“Coffee and cancer”
Kort sammendrag av avhandlingen:
Norway has a long tradition when it comes to coffee consumption. Between 1997 and 2011, average consumption of coffee in Norway was 9.4 kg/year per capita, second highest in the world, trailing only behind Finland. In 2016, the International Agency for Research on Cancer published a Monograph in which they have stated that coffee drinking was not classifiable as to its carcinogenicity in humans. What this means is that there is no convincing evidence that coffee consumption is harmful when it comes to risk of cancer. In fact, what the Agency further said is that coffee consumption might have a protective effect on developing certain types of cancer such as liver or uterine cancer.
We aimed to investigate the effect of drinking more than seven cups of coffee per day on the cancer risk. They have used the information on coffee consumption that were collected during 90s from around 100 000 Norwegian women that are part of the ongoing Norwegian Women and Cancer Study. We found that even consuming large amounts of coffee on daily basis does not affect your chances of cancer, specifically bowel, breast, and cancer of the ovaries. Women who drank more than 7 cups of coffee had a two times increased risk of lung cancer compared to women who drank no more than one. However, it is well established that active smokers are more likely to be heavy coffee consumers, and they will need more caffeine compared to non-smokers in order to feel the effect of it. Therefore, we repeated the analyses by using only the women who had never smoked. The result – no increased risk of lung cancer even if you drink large amounts of coffee.
Moreover, we combined the data from Norway (Norwegian Women and Cancer Study) and Sweden (Northern Swedish Health and Disease Study) to explore how coffee drinking was related to the risk of some cancer types that are rarely diagnosed. In the analyses that involved almost 200 000 men and women, we found that drinking more than 4 cups of filtered coffee a day was reducing the risk of pancreatic cancer for 25% compared to drinking no more than one cup of this type of coffee a day. On the other hand, coffee drinking was not influencing the risk of bladder, esophageal, kidney, and stomach cancers in any way.
Finally, we pooled together the results from all previously published scientific papers that aimed to determine if coffee drinking was affecting the risk of endometrial cancer. The meta-analysis conducted has shown that coffee drinking was greatly reducing the risk of endometrial cancer. However, this effect of coffee seems to be apparent only in women that have body mass index over 30 (women with obesity).
So next morning, put on your coffee kettle on a stove, or fire up the coffee machine. On the way to work, do not fear to have another cup to go and enjoy your coffee during boring meetings. Rest assured that the coffee you have (been drinking) drunk would not affect your health, at least when it comes to cancer. However, as there are many other diseases, which still need to be researched in regards to coffee drinking, keep in mind that moderation, is always an option.
Hovedveileder Førsteamanuensis Tonje Bjørndal Braaten
Biveileder professor Tore Eiliv Lund
Professor emeritus Dag Thelle, Universitetet i Oslo – 1. opponent
Professor Petra Wark, Coventry University, England – 2. opponent
Forsker Laila Hopstock, Institutt for samfunnsmedisin, Det helsevitenskapelige fakultet, UiT Norges arktiske universitet – leder av komité
Førsteamanuensis Erik Eik Anda , Institutt for samfunnsmedisin, Det helsevitenskapelige fakultet, UiT Norges arktiske universitet
Prøveforelesning over oppgitt emne holdes kl. 10.15, samme sted: “Should p-values still be used? Causal inference in epidemiology”