Dispatches from the War on Cancer: Detection as Prevention, Chronic Disease as Cure
Ten years ago on June 25, 2008, I was diagnosed with colon
cancer. My grandmother passed away the night before. She was just two weeks shy
of her 96th birthday. I had planned to spend it with her. Instead, I
re-routed the frequent flier miles I was to use for that visit to a plane
ticket for my mother, who had now just lost her own mother, to be with me for
my immediate surgery. Needless to say, this was one of the worst days of my
life as well as my mother’s. Mortality had reached my beloved grandmother, and
in nearly the same instant, had come for me.
After finding a tumor in my colon, following a colonoscopy
necessitated by several alarming symptoms that had progressed over five years,
the results of the toxicology test on my tumor confirmed its malignancy. This shocked
my doctor because I had no known risk factors, but I was not surprised. Though I
followed a fairly impeccable vegetarian diet for the preceding 15-20 years full
of a plethora of whole food - largely from the influence of my Italian
grandmother’s culinary mastery and the stupendous, nutritious peasant cuisine
her poor immigrant family grew up eating - I knew that did not necessarily
serve as a cancer inoculation. Though I had been a non-smoker my whole life as
well as an athlete, I knew that neither of these factors necessarily prevented
the diagnosis I ultimately received. Though I had no family history of colon
cancer – and scant family history of cancer at all – I still suspected the
malignancy. And though every doctor I have seen before or since characterized
my cancer as a fluke, I knew it was not.
In the few years preceding my diagnosis, handfuls of friends
and acquaintances in my age group had fallen victim to forms of cancer. An old
neighbor in her 20s and a dear friend in her 30s had both recently died of the
disease. The stories of cancer in friends, coworkers, acquaintances, old
classmates and their spouses, and friends of friends accumulated. Anecdotally,
I saw cancer incidences rising in lower age groups. I felt that I was noticing
more cancer among my peers than in my parents’ and grandparents’ generations
before me. As a scientist, I knew my personal observational data was not
sufficient for any conclusions, so I waited for possible confirmation. I found
it when I learned that melanoma,
metastatic
breast cancer, and colorectal
cancers were all on the rise in young and middle-aged adults. These data fly in
the face of the notion that cancer has been increasing mainly because it is an old-age
disease and more people in our American population are living longer.
In March of this year, the alarming rise in colorectal
cancers in younger populations prompted the American
Cancer Society to recommend colon cancer screening start at age 45 instead of
50. As always, the recommendation for protection against colon cancer
stresses keeping a healthy lifestyle, which includes plenty of exercise, a
wholesome diet, and maintaining a healthy weight. To summarize, our colon
cancer prevention plan consists of: 1. The generic “healthy lifestyle” and 2. Regular
screenings, which are technically not preventative measures but rather
diagnostic measures.
In beautifully crafted public relations rhetoric, the
medical establishment has defined diagnostic screenings as secondary prevention, and treatment to
manage disease and thwart its exacerbation and recurrence as tertiary prevention. Perhaps two
additional levels of disease “prevention” were needed because we are so
woefully inadequate at the first. The only real form of prevention – primary prevention in medical jargon –
is never contracting the disease.
In truth, the etiology of colon cancer is not well known.
Several gene susceptibilities increase risk, but
these genes factor into the risk equations for only approximately 5% - 10% of
colon cancer diagnoses. That a high fiber diet protects against colon
cancer – while a diet rich in meat products does the contrary – is conventional
wisdom within the medical community, but
scientific support for this premise is actually scarce and inconclusive. Some studies
have demonstrated a correlation between exposure to
chlorinated byproducts in water, but these too are far from conclusive. New
research links exposure
to triclosan, an antimicrobial compound found in many household and personal care
products, to colon cancer. Triclosan had already been
deemed a suspected carcinogen, but this new evidence shows that its
mechanism for oncogenesis likely has to do with its disruption of the gut
microbiome, reducing necessary and beneficial bacteria in the digestive system.
This research then also suggests than any agent, such as an antibiotic or a
pesticide, that could affect our intestinal microbiome might, in turn, induce cancer.
But what caused my own cancer? I will never know. I drank gallons and gallons
of highly chlorinated municipal tap water during the decade I lived in D.C. I
used liquid soap containing triclosan for several years in the 1990s before I
decided than antibacterial soap was overkill, and I wanted to reduce the waste from
the plastic containers it came in. It could have been anything I’d unknowingly
been exposed to in my food, water, or air. It could have been chemicals I’d
been exposed to in laboratories in school. (Stupidly, we tended to flout a lot
of precautions in our college chemistry labs.)
It could have been radioactive materials I might have been exposed to in
the neighborhood I grew up in, which was in close proximity to a nuclear
reactor. (Of note; the proposed National Academy of Sciences study on
cancer risks in communities that house nuclear reactors was halted, citing “prohibitive
costs,” so I will probably never have any data one way or the other
regarding that potential risk.) It is unlikely my cancer could be attributed to
one particular cause; more likely, it was the combination and accumulation of a
multitude of factors that can never be fully ascertained, as is the case in
most cancer patients.
The one factor that did not directly cause my own cancer is an inherited gene because,
technically, we
do not know of inherited genes that, in and of themselves, directly cause
cancer. More importantly, they are implicated in only a minority of cancers overall - 5%-10% of cases. The increasing rates of
cancer incidences over the past four decades (the only time period for which we
have incidence data) cannot be explained through inheritance. Neither can the increasing
rates of cancer in younger populations. If heritable alleles (the different
forms of genes) caused terminal diseases like cancer and had no beneficial
effects, evolution and natural selection would favor the decrease in these
genes in the population. If these genes were initially a huge contributor to
cancers, the genes would have been selected against, and cancers would have
been declining in humans over time. That has not occurred. Moreover, in terms
of the alleles that confer genetic susceptibility to cancer, like BRCA1 and
BRCA2 in the case of breast cancer, the relative risk of a woman with these
alleles developing cancer has increased
over time. That is, women
with those gene variations born before 1940 have only about a 24% risk of
developing cancer while women born after 1940 have a 67% risk, which means
these genes are not the major component of that cancer risk, but the majority
of the risk comes from elsewhere – from something interacting with the genes
that has changed over time. With colon cancer, for example, the majority of
inherited genetic abnormalities linked to colon cancer produce precancerous
colon polyps, but it is estimated that even 95%
of precancerous polyps will not form cancer. Consequently, it would appear
that there may be some other environmental component prodding these
precancerous cells into becoming cancerous. Because of the marked focus on
heritable “predispositions” to cancer, it appears we might be missing the fact
that even these inherited susceptibilities need exogenous environmental factors
to eventually result in cancer.
The complexity of cancer itself and of the variety of
factors that contribute to it makes direct cancer causation difficult to
pinpoint. Statistics
from American Association for Cancer Research suggest that tobacco use
contributes to between 30-35% of cancers, with obesity a close second,
contributing to about 20-25% of cases. But if you examine this and similar statistical
charts on relative contributions to cancer incidence, you will see that they include
nebulous contributions like diet, inactivity, and obesity, which, in themselves,
have no known mechanism to cause cancer, as well as factors like UV radiation,
alcohol, and certain pathogens (like viruses) which are known carcinogens. It
does not make logical scientific sense to mix known causes of cancer with
susceptibility factors in the same general category of this chart, and it puts
into question the soundness of the entire analysis. It obfuscates the
complexity of cancer causation by comparing causes and risk factors, as if they
are the same. It is like constructing a chart about contributors to flu
incidence and including the flu virus at 40%, compromised immune system at 25%,
lack of hygiene at 15%, poor diet at 15%, and lack of exercise at 5%. The only
factor that actually causes the flu is exposure to the flu virus; all of the
others might increase risk and susceptibility. The only factors we know of that
actually cause cancer are carcinogens, substances that directly or indirectly
cause mutations that disrupt the normal cycle of cell division in our body.
These include radiation, naturally occurring and synthetic chemicals, and
various pathogens.
In any case, even these questionable charts make clear that
the vast majority of cancers are highly preventable. The 2010 report
of the President's Cancer Panel noted that there are so few data
on the hundreds of thousands of chemicals and toxicants in our society, and we
have not quantified, and perhaps will not be able to quantify, the cancer
burdens from these toxicants. For example, we assume that our regulatory
agencies ensure that we are only exposed to carcinogens at low enough levels to
keep us generally safe from disease, but we know in practice, this is often not
the case. We also know that some types of chemicals that can cause cancer, like
endocrine
disruptors, do not necessarily have safe levels, because they are actually more
harmful at lower than higher concentrations. We also know that some
chemicals that are fairly innocuous alone become carcinogenic agents when in
particular mixtures. The cancer burden from all possible mixtures of
chemicals, which is what humans are regularly exposed to in their lives, is
basically unquantifiable and unknowable. And if we cannot quantify the relative
contribution of environmental exposures to cancer incidences, then we really
cannot truly quantify the relative contribution of other causes either. The
panel concluded that “the true burden of environmentally induced cancer has
been grossly underestimated.” Developing
nations like
China are experiencing surges in cancer rates, which they attribute to
exposure to carcinogens from industrial
pollution. India,
a country with relatively low cancer rates, has seen tremendous increases in
places where carcinogenic substances like pesticides
abound. In addition, humans
are inducing cancer in other wildlife species, largely due to pollution.
This evidence lends more support to the conclusion of the President’s Cancer Panel
that environmental toxicants may be contributing to far more cases of human
cancers than we acknowledge. Furthermore, it lends credence to the fact that most
cancers could be preventable if environmental toxicants were removed from the
equation.
While overall incidence of cancer has
declined a bit in recent years (possibly due to a sharp decrease in tobacco
use), and cancer death rates have declined modestly (possibly due to more
effective treatments), cancer still affects over 40% of the American population
and is the second leading cause of death in the U.S.
Diagnostic tests are a good stopgap measure in the short
term to deal with the increasing rates of colon cancer in younger adults; however,
given that cancer is largely preventable, our long-term goal should be to
implement measures that focus mainly on prevention. Not only do too many people
in the United States
lack access to affordable medical care, medicine is not without its own
contribution to our public health crisis. Certain diagnostic tests themselves,
such as X-rays and CT scans, may contribute to
excess incidences of cancer. In addition, the enormous environmental
resource use in the medical industry, and its waste stream, which includes
radioactive chemicals, pharmaceuticals, and plastics, both inevitably
contribute to the environmental degradation and pollution that threaten our
ecosystems and increase our public health burdens.
Sickness is not the default state of organisms, so we should
strive to maintain health and prevent the burden of disease as best we can. Of
course we should eat well, exercise, and avoid alcohol and smoking as much as
possible. But these measures are not enough. In terms of cancer, prevention
should mean focusing on reducing and eliminating the only agents that we know
to actually cause cancer – carcinogens. They exist in our food, in our water,
in our air, and in our products. Far too many are there merely for profit and
convenience, not necessity.
Forty-seven years after President Nixon declared a war on
cancer, we still have battles raging all around us. In most cases of cancer, we
are no closer to cures. Some doctors are expressly saying that we will never
cure cancer, but in the future it will be a chronic, manageable disease. For a
supposedly highly advanced society, this solution to cancer falls pathetically
short of what should be. For victims of cancer and their friends and family,
the thought of living with never-ending cancer treatments along with the
anxiety produced by a disease that could always become terminal is horribly
unsatisfactory.
We are playing Russian roulette with our lives by not
addressing so many of the preventable causes of cancer in our society. The oft
repeated metaphor about cancer, “the genes load the gun, the environment pulls
the trigger” rings quite false. Our toxic environment is the gun and without that environment, the bullets are useless.
We need gun control.
* All statistics about cancer above refer to data in the United States,
unless otherwise noted.
Kristine Mattis holds
a Ph.D. in Environment and Resources. She is no relation to the mad-dog general.
Email: k_mattis@outlook.com
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