Cancer and All-Cause
Mortality among British
and German Vegetarians
What is the evidence from studies of other populations that vegetarians experience different rates of cancer mortality or of mortality from all causes? The Health Food Shoppers, Oxford Vegetarian, and Heidelberg studies (see Chapter 10) addressed the risks of dying from cancer, or from any cause, among non-Adventist vegetarians. In addition, a collaborative analysis that combined the results of these studies with those of California Adventists compared cancer and all-cause mortality among vegetarian and nonvegetarian subjects.
AND GERMAN VEGETARIANS
It is important to understand that the information presented here pertains only to those cancers that were sufficiently invasive or advanced, at the diagnosis stage, to have caused death. For most common sites, this would exclude 50% to 70% of new cancers, although for cancers that are highly fatal (e.g., cancers of the lung, stomach, and pancreas), most events are included. The only study of many vegetarians that has so far published results for all new cancers, both fatal and nonfatal, is the Adventist Health Study, and these results were discussed in Chapter 6.
A problem that pervades prospective studies of cancer is that of small numbers. As the studies of non-Adventist vegetarians are either small (the Heidelberg study) or moderately sized (the two British studies), the numbers of cancers for specific sites are also quite small, and this leads to wide confidence intervals. In the data presented below, results based on less than 10 recorded cancer deaths for a particular site are excluded.