Three stages of cancer: Initiation, Promotion, Progression
Cancer develops in three stages: initiation, promotion and progression. Professor Campbell’s analogy in his book, The China Study, is spot on so I’ll steal it. He says that the cancer process is roughly like planting a lawn. Initiation is when you put the seeds in the soil, promotion is when the grass starts to grow and progression is when the grass gets completely out of control, invading the driveway, borders and pavement. It is carcinogens (cancer causing agents) that ‘implant’ the seeds in the soil in the first place and these include tobacco smoke and alcohol but are mostly the by-products of industrial processes. They mutate normal cells into cancer-prone cells by damaging their DNA.
This is why diet is so important. There are dietary factors (known as promoters) which feed cancer growth and there are others (anti-promoters) which slow cancer growth (Campbell et al, 2005).
A wholefood vegan diet, brimming with fresh fruit and vegetables, wholegrains, pulses, nuts and seeds may significantly protect against the DNA damage by carcinogens – so diet is vital. For example, it is known from a recent study (Riso, 2010) that broccoli directly protects the lung cells of smokers (see Dr Michael Greger’s short film at http://nutritionfacts.org/video/dnaprotection- from-broccoli). There are also studies showing that specific foods help prevent or repair DNA damage that can cause cancer – including apples, almonds, grapes, carob, Brussels sprouts, black pepper and soya (edamame, tofu and tempeh). (See http://nutritionfacts.org/topics/dna-damage.) So, certain plants in our diet can stop the initial cancer seeds being created - and, thus, can impede the stages of cancer.
If a cell is damaged, however, and it passes that DNA damage on to its daughter cells, the process is irreversible. Daughter cells and their progeny will forever be genetically damaged, giving rise to a potential for cancer – but the key word here is “potential”. The next process – promotion – is not inevitable. The grass seeds are ready to germinate but they need the right conditions in which to grow. They need water, nutrients, sunlight… otherwise they lie dormant. Cancer-prone cells also need certain conditions to multiply but promotion is reversible. This is really quite profound and depends upon whether early cancer growth is given the right conditions in which to prosper. This is why diet is so important. There are dietary factors (known as promoters) which feed cancer growth and there are others (anti-promoters) which slow cancer growth (Campbell et al, 2005). Campbell’s studies led him to believe that casein from cows’ milk aggressively promotes cancer but, equally significantly, vegetable proteins do not, even at high levels. Campbell widened his studies and found that nutrients were more important in the development of cancer than the dose of the initiating carcinogen which started the process. Campbell and his colleagues were then given a rare opportunity to study the role of nutrition, lifestyle and disease on people’s health in the most comprehensive manner ever undertaken in the history of medicine. They were onto The China Study.