Cancer exists because you don't need to live to 150 years old to successfully reproduce. It costs too much from a biological perspective to prevent cancer, calories and nutrients better spent on raising children and to some extent grandchildren.
People got cancer back when the environment was pristine, they were just more likely to get eaten by the crocohippo first.
The observation is always the same: Cancer is one of the "western diseases" that starts appearing in native populations when they are exposed to colonists. And it's not just because of longer lives: people start getting cancer at higher rates at earlier ages.
Taubes blames the problem on insulin-like growth hormone that is secreted in response to high-carbohydrate foods, and creates an environment perfect for rapid cell growth. Pollan doesn't speculate on the cause, other than to say that there is something wrong with the western diet. Jaminet speculates that we will find more types of cancer are cause by infectious agents, since cell immortality and rapid reproduction is a perfect strategy for a virus and since we have found several so far: http://en.wikipedia.org/wiki/Infectious_causes_of_cancer
Galen in 2nd century AD observed cancer, and used the term "oncos" to describe it. Celsus in 1st century AD did the same, and used the term "cancer" for the first time. Hippocrates in 4th century BC described several different types of cancer and called them, generically, "carcinos" ("crab" in Greek).
Egyptian texts from at least 1600 BC, with some going back to 3000 BC, describe different cases of cancer, noting with regret: "there is no treatment".
Dinosaurs, 65 million years ago and more, suffered from various types of cancer such as hemangioma, desmoplastic fibroma, and osteoblastoma.
Cancer is, has been, and always will be the evil shadow of all multicellular life.
Please, don't take your medical and scientific information from a "liberal foodie intellectual" with a B.A. in English (not that there's anything wrong with any of these attributes in particular, they're just not qualifications to talk competently about cancer).
http://www.cancer.org/cancer/cancerbasics/thehistoryofcancer...
http://web.archive.org/web/20110716111312/http://www.cancerd...
http://www.bordet.be/en/presentation/history/cancer_e/cancer...
http://www.academia.edu/227680/Epidemiologic_study_of_tumors...
"An interesting phenomenon has arisen during the course of multi-year studies related to the rarity of cancer in antiquity. This is of interest especially when considering that hundreds of Egyptian mummies and more than 10,000 dinosaur bones were evaluated. In contrast, the rate of cancer incidence has dramatically increased since the Industrial Revolution. The rarity of cancer in antiquity has been attributed to the lack of pollution and changes in diet and lifestyle, and most recent findings suggest that cancer may be a manmade disease (Nat Rev Cancer 10, 728–733). Thus, while a lack of adequate techniques for disease diagnosis and detection may partially explain the overall lack of cancer found during the millennia, the current cancer trends are now primarily associated with carcinogens in our modern industrialized society (Nat Rev Cancer 10, 728–733)."
I am not a fan of pseudo-scientific, moral-panicky speculations about the evils of "modern life" from the likes of Pollan et al. myself; but in this particular case, as your article explains, there is considerable evidence that cancer (standardized) prevalence was indeed much lower in pre-modern societies. Also, for some types such as colorectal cancers, some dietary habits (prevalent, as it happens, in modern societies) are very well-known and well-established risk factors, accounting for up to a 70% increase in relative risk in some studies [3].
As I said: I symphatize with your view, but be mindful of confirmation bias.
[1] Eg. controlling for age and other risk factors in the study population.
The actual causes are less well understood. One hypothesis is that we live longer, but given studies that have tracked aboriginal people who moved into cities and compared them against their native kin have shown an increase in the Western cancers, that hypothesis is weak at best. Beyond the unhealthy SAD ("standard American diet"), we also have pollutants, stressors, and who knows what else that can influence cancer.
So you're left with a slew of variables and a lot of sick people. Fifty years ago, cancer was seen as a metabolic disorder, and maybe some are. One of the largest pieces of evidence for this is cancer's inability to metabolize anything but glucose for energy. Cancers that are metabolic diseases would certainly be affected negatively by a growth-hormone-rich environment coupled with consistent access to as much blood sugar as the cancer wants.
Trying to oversimplify with "it's the bread" causes a near visceral reaction in many people, which is unfortunate, because, while it may not be the bread, the bread may be acting as Miracle Grow for the cancer. For me, I'm choosing a diet that, hopefully, won't be an energy smorgasbord for tumors.
Unhealthy eating (especially very salty/spicy/fermented foods), alcohol use, and so on also classify as environmental factors. But they are not caused by pollution or chemical-laden foods, merely bad life choices. Copious quantities of red meat isn't good, organic or no.
I don't meant to imply our bad handling of the planet causes no cancer, it certainly does. But it does not cause anywhere close to 90% of cancer cases. Not by a long shot.
The point stands. How many people consciously make an effort to prevent cancer in every aspect possible? On a personal level as much as a societal level, we're doing little to address the preventable causes of cancer. Why are so many people making so many "bad life choices"?
The wikipedia article on capsaicin links to this study as well as several others and indicates that capsaicin may have carcinogenic or anticarcinogenic properties based on several studies: http://en.wikipedia.org/wiki/Capsaicin#Effects_of_dietary_co...
You probably shouldn't be all that concerned about eating spicy food... on the other hand, if you don't smoke, you eat well, and you aren't obese, you're roughly 55-65% less likely to die of cancer: http://en.wikipedia.org/wiki/Cancer#Causes
[1]: http://www.amazon.com/Emperor-All-Maladies-Biography-Cancer/...
"Cancer is caused by both internal factors (such as inherited mutations, hormones, and immune conditions) and environmental/acquired factors (such as tobacco, diet, radiation, and infectious organisms). The link between diet and cancer is revealed by the large variation in rates of specific cancers in various countries and by the observed changes in the incidence of cancer in migrating. For example, Asians have been shown to have a 25 times lower incidence of prostate cancer and a ten times lower incidence of breast cancer than do residents of Western countries, and the rates for these cancers increase substantially after Asians migrate to the West."
http://en.wikipedia.org/wiki/Cancer#Causes
We need to fix our environment instead of hacking ourselves to deal with a broken one.