'How is it we have cancer?' is indeed a massive question, but the answer may be simpler than you think. More to the point, if you know the answer then there are a number of preventative measures you could take to avoid cancer.
Mainstream medicine and their researchers hold the official line that cancer is something they don't really understand. They don't really understand its causes and what it is. They go on about how they're busy mapping the genes that cause the disease to find its aetiology.
It's not about what your genes are. It's about the expression of your genes and what causes them to be expressed: Basically, we bring cancer on our own selves. It's a result of how we look after our bodies and how we deal with stress...
Cancer is the result of an accumulation of body toxicity and long-term stress. A clue to body toxicity may well be in the rising obesity rates. Many of us eat too many junk foods, sugar-laden drinks like soda pops... Then there are those diet drinks, if consumed in numbers over time this could lead to brain cancer due to the chemical artificial sweeteners...
Too many people systematically do the wrong things have developed into habits. This includes using toxic chemical lotions, potions, and hair and skin carcinogens. Drinking fluoridated water adds to the toxicity list. Many people cook their food to death, destroying the vitamins and enzymes present as their food value goes right down. The same thing happens when people use the microwave oven which makes the food toxic and irradiated.
Excessive and continual consumption of junk food and sodas give an acid body. This internal acidic environment allows cancer to set in. Pathogens thrive in an acid body. Standard diagnostic lab tests used to culture pathogens have an acidic environment prepared because because this is how they grow these nasty little critters!
What I'm getting at is if alkaline foods are eaten (especially those that are raw) then this is part of a solution to staying cancer free. Alkaline foods when absorbed give a healthy alkaline body. Cancer cannot grow in this environment.
Good examples of healthy alkaline foods include: Lemons, garlic, Cayenne peppers (capsicum), leafy greens like spinach and kale (has plenty of fibre, vitamin K and folate with antioxidants which encourages digestion). Other vegetables include the cruciferous kind like cabbage, broccoli and cauliflower. Most root vegetable are also alkalizing like carrots, beets and turnips.
In short good diet, handling stress and avoiding toxicity is the solution for us not to give ourselves cancer.