The Cancer Chronicles
Unlocking Medicine’s Deepest Mystery by George Johnson (Knopf)
Eating beef won’t give you cancer; fruits and vegetables won’t save you from it. And for all the time people spend racing for a cure, they might as well be running in place.
These are just a few of the conclusions of “The Cancer Chronicles,” in which science writer George Johnson presents the many theories that have come and gone about the disease, his take (based on extensive research) on what gives people cancer and what doesn’t and his own personal experience with the disease via his former wife Nancy’s harrowing, but ultimately victorious, battle with metastatic cancer.
Most likely to provoke disꦫcussion are his conclusions about cancer’s causes. Other than the smoking of tobacco greatly increasing lung-cancer risk and obesity increasing chances of getting the disease overall, Johnson makes the case that there are few absolutes in this area, as he debunks many of the 🍰causes and preventative measures we take for granted.
VEGGIES DON’T HELP
One of the supposedly healthy approaches he treats as myt🅺h is the eating of fruits and vegetables as a cancer preventative.
A much-hyped report from the National Cancer Institute in the 1990s recommended five servings a day, saying that fruit and veggies “appeared to have remarkable powers,” and that their consumption could lower incidences of cඣancer “by over 20%.”
Johnson says their actual powers in this area are almost nil, citing a 2007 follow-up based on “more and better evidence” that concluded that “in no case now is the evidence of protection🐼 judged to be convincing.”
The problem with the initial report, as with many previous long-term cancer studies, was that it relied on “retrospective studies,” which require people to remember what they ate “years and even decades e𓆉arlier.”
These problems led to the formation of the European Prospective Investigation into Cancer and 🔯Nutrition (EPIC), which used more direct investigative methods, including “monitoring the health of 520,000 people in 10 countries” over the course of many years.
Johnson cites the EPIC studies as the basis for 🐷several of his conclusions, including t▨hose on produce.
“The largest prospective study on d🅷iet and health,” Johnson writes, ꦰ“has found so far that eating fruits and vegetables has, at most, a very weak effect on cancer prevention.”
Also knocked off their perches are fiber, which has been said to help prevent colon cancer, claims that Johnson says have 🦹been debunked; and fish, as he notes that any “firm connection” between fish and preventing cancer “has remained elusive.”
MEAT DOESN’T HURT
Much as we have been mistaken about foods that could save us from cancer, so too, writes Johnson, have we been misled about🅠 what causes the disease, or at least how gravely some of these items incrဣease our chances.
According to 💞one EPIC study, the effect of eating meat on our odds of getting cancer is far small𝓀er than many believe.
While “eating a lot of red meat every single day might have raised our chances of getting colorectal cancer during the next decade by as much as a third,” that percentage increase is only “from 1.28% to 1.71%.” Break this down a diff🍌erent way, and the study estimates that eating 160 grams of red meat — which is more than a third of a pound — every single day increases cancer risk just 0.43% compared to someone who eats less than 20 grams per day. This percentage risk, writes Johnson, made “cooking a giant steak on the weekend seem worth the trade-off.”
Johnson also notes that our odds of getting cancer from chemicals𒐪 or environmental contaminants are very small.
The environmental movement that ignited in the 1970s brought 𒐪about widespread fear of chemicals such as pesticides, saccharine and Red Dye No. 2. Many felt that a cancer epidemic was on its way, and the belief that “90% of cancer is environmental” became widespread — while at the same time remaining wildly off-base.
A 1981 study by Richard Doll and Richard Peto, the epidemiologists who had earlier established the links between cancer and both smoking and asbestos, used far more expansive methodology than earlier💫 studies. Called “The Causes of Cancer,” it made the case that less than 8% of cancer deaths overall were caused by artificial carcinogens, including less than 1% overall caused by “either industrial products like paints, plastics and solvents or food ☂additives.”
It should be noted here that while Johnson relies heavily on percentages to make his points, looking singularly big picture, he doesn’t address how even small percentages could represent big numbers.
The American Cancer Society, for instance, estimates that more than 580,000 Americans will die from cancer this year. So if we’re talking about less than 1% of that, it’s conceivable th💎at we could still be talking about over 50,000 American deaths this year alone.
CARCINOGEN MYTHS
That said, Johnson’s conclusions d𒉰o call into question many common perspectives♉ on the disease.
He discusses “cancer clusters,” geographic areas where a larger-than-normal group of people develop a similar type of cancer a💖t the same time and claims that they are “statistical illusions” for which the cause is almost never any of the feared environmental factors.
When breast cancer became prevalent on Long Island in the early 1990s, for example, people feared causes such as the radiation from a local research lab, high-density power lines o💮r use of pesticides or DDT. But༺ a $30 million study by the National Cancer Institute found no link between pollutants and the cancer and also determined that the Long Islanders’ incidence of cancer was similar to much of the Northeast, leading Johnson to believe that their suburban lifestyle — overeating combined with not enough exercise, among other factors — was the more probable cause.
So, why are so manyꦯ people convinced that environmental factors will give us cancer? Part of the exagger♓ated fear, Johnson writes, came from a misunderstanding of the implications of the word “carcinogenic.”
The early work of famed cancer researcher Bruce Ames led to the banning of certain artificial carcinogens in children’s pajamas and hair dyes ♐and also helped tighten regulations on pesticides.
But after helping spread the word about the🔯 danger of artificial chemicals, Ames tested natural ones and found that “a surp💃rising number also appeared to damage DNA.”
Ames “r⛎eported that of 63 natural substances found in plants, 35 tested as carcinogenic. His most striking example was a cup of coffee, [with] 19 different carcinogens. Altogether, he estimated, people were imbibing 10,000 times as many natural pesticides as manufactured ones.”
Ames’ point was not for people to start freaking out and fearing plants, but rather that just because something is a carcinogen, that doesn’t mean we’ll be exposed to it in high enough doses to give us cancer.
“Ultimately Ames’ message was that we were worrying too much about both kinds of chemicals, natural and artificial,” Johnson writes. “Half of everything he tested was registering as carcinogenic, but that didn’t necessarily mean that the substances were dangerous.”
DEBUNKING THE BOMB
Even nuclear radiation, he writes, is nowhere near as likely to kill🔯 us as we’d believed.
“Not even the radiation from nuclear blas🌞ts, accidental or deliberate, has caused nearly as much cancer as most people think,” writes Johnson, who again pooh-poohs some large numbers in presenting his percentages.
He writes, for example, that among those who received the highest exposures to radiation during the Chernobyl disaster, 4,000 eventually died of cancer. That sounds like a lot of deat⛦h, but Johnson notes that it’s less than 1% of the 600,000 people who were exposed to these massive levels of radiation.
To reinforce his point, Johnson adds that scientists monitored 90,00ꦗ0 survivors of the nuclear blasts at Hiroshima and Nagasaki during World War II and found that only 630, or also less than 1%, develo☂ped cancer. He also cites the case of a man who survived both blasts and lived until 2010, dying at the age of 93.
ꦰIf the reader can🌟 see fit to dismiss 4,000 deaths here and 630 there, then Johnson’s point can be well taken. Given that most of us probably believe that the sort of radiation left in the wake of an atomic attack would be a certain death sentence — eventually, if not right away — then learning that the odds of getting cancer from that are actually less than 1% is a pretty significant shift.
STOP SMOKING, LOSE WEIGHT
So if all the things we feared would give us cancer most likely woꦓn’t, then what will?
Johnso🀅n describes the current thinking about cancer as centering ♈on two factors: smoking tobacco and obesity.
While tobacco smoke’s effect on lun🐷g cancer is long established, the prominence of general weight control in overall cancer prevention — as opposed to eating certain foods and avoiding others — is a more recent development.
One EPIC study showed that “older women who had gained . . . roughly 40 pounds since they were 20 had an increased breast-cancer risk of 50%” an꧃d that “along with lack of exercise, [obesity] may account for as muc🙈h as 25% of cancer, with dietary specifics falling to as little as 5%.”
Increased breast-cancer rates for women have also risen due to girls reaching puberty earlier than they used to and women having fewer children than in previous gꦅenerations, two factors that combine to give the average woman far more menstrual cycles than women from previous eras.
“With each period, a jolt of estrogen causes cells in the uterus and mammary glands to⛄ begin multiplying, duplicating their DNA,” he writes. “Each menstrual cycle is a roll of the dice, an opportunity for copying errors that might result in [abnormal growth or division of cells].”
Such is the power of these circumstances to cause cancer that the Na🌜tional Toxicology Program lists estrogen as a carcinogen.
RANDOM & COMPLEX
﷽Johnson emphasizes the complexity and randomness of cancer, saying that some in the scientific community think of cancer as “tens of thousands of diseases each with i✅ts own molecular signature.”
Much of the point of this book, then, is that for all we’ve learned, all we’ve done and all we’ve tried to control, there is still a randomness to cancer that we have not come close to reining in, since “of the multiple mutations it takes to start a cancer, there is no way to know which was caused by what.”
Hopes for a cure, then, are so far off and elusive that Johnson wonders if well-meaning charities like Stand Up to Cancer aren’t merely raising false hopes. The more we learn, the more it appears that cancer’s complexity makes prospects for a cure fairly dismal. (In comparing the effort to cure cancer to our having cured polio, Johnson notes that polio was a disease with a single cause, whereas any particular cancer can be one of many sorts of dysfunction in an infinitely complex cellular system.)
The best-case scenario is that scientists will one day understand the intricacies of cellular activity deep enough to craft tightly targeted ꦡcures, but that day is not in our foreseeable future.
“One day, as t൲hese technologies develop,” Johnson writes, “scientists may be able to routinely a🐻nalyze the unique characteristics of every individual cancer and provide each patient with a personally crafted therapy. It is a lot to hope for.”
Until that miracle cure arrives, the best any of us ca🔜n do is lose weight, exercise, don’t smo🔴ke and hope for the best.
“Whether any⭕ one person gets cancer or does not 🌄will always remain mostly random,” he writes.
“As Doll and Peto put it, ‘Naꩵture and nurture affect the prob🐽ability that each individual will develop cancer.’ But it is luck that determines which of us really do.”