Unraveling the Chemicals-Cancer Link Could Help Dethrone the Emperor of All Maladies
In May of 1999, a 52-year-old cardiologist and his 22-year-old daughter sat down for lunch in upstate New York. The man ordered his favorite sandwich, a BLT. They talked about her upcoming college graduation. The man stopped eating, looked uncomfortably full and slightly nauseous. She was quietly worried. It’s just heartburn, he said.
The man was my father. Far from just heartburn, he was soon diagnosed with an aggressive form of stomach cancer and died at home in his bed less than a year later, on February 9, 2000, just after midnight.
So when reading oncologist Siddhartha Mukherjee’s Pulitzer Prize-winning biography of cancer, The Emperor of All Maladies, I was especially drawn to the story his patient Germaine Berne. Just a few months after my lunch with my father, Berne, a 46-year-old psychologist near Montgomery, Alabama, found herself overcome with severe nausea and plagued by a ceaseless sense of being overstuffed. She hopped in the car and drove herself to the hospital.
Diagnosed on January 4, 2000, with the same form of stomach cancer as my father, Berne lived nearly six years, vastly outstripping her life expectancy, thanks to the aid of what was then a brand-new, cutting-edge chemotherapeutic treatment.
The medication, Gleevec, reworked the molecular circuitry that was misfiring in Berne’s tumor, altering what’s referred to as a pathway to disease. Gleevec wasn’t available to my father when he began his chemotherapy treatments. Whether it might have given him the additional six years of life that would have allowed him to see the rest of his four children graduate from college is anyone’s guess. I have no reason to believe that would have necessarily been the case.
But the contrasting stories of my father and Mukherjee’s patient -- though they were diagnosed within six months of each other, their diseases took radically different turns under different treatments -- seems to underscore how far we have to go to fully unravel this disease, to understand its triggers and plodding progression, and to figure out how to successfully prevent or treat it.
I picked up The Emperor of All Maladies just as my most recent article for OnEarth, on the rapidly emerging field of green chemistry, was going to press. As I learned in the course of reporting the story, scientists and public-health advocates are increasingly alarmed by how little we know about the effects of many tens of thousands of manmade chemicals that circulate in our environment, hundreds of which are now commonly found in the human body.
A growing number have been shown to have irreversibly devastating effects on human health, including -- just to name one -- a class of common plastic and perfume additives called phthalates, which interrupt the production of testosterone. One of the side effects of maternal exposure to phthalates during pregnancy is undescended testicles in newborn boys, a condition that can be surgically corrected but is also linked with higher rates of testicular cancer later in life.
And the list of chemicals that have suspected or confirmed links with chronic diseases, including cancer, continues to grow. Just this month the Environmental Protection Agency classified several common chemicals as human carcinogens, including formaldehyde (which is commonly used to make compressed wood products and is found in many building supplies). Styrene, used to make plastics and household items like Styrofoam cups, was classified as reasonably anticipated to cause cancer.
Of course, one night’s sleep on the wrong bed or a sip from a Styrofoam coffee cup is not a death sentence, but the precise levels of chemical exposure, weighed against other differences in susceptibility that vary from person to person, remain poorly understood. The government’s new warnings seem to say: We know this can cause some cancer sometimes, but that doesn’t necessarily mean it will happen to you.
Mukerjee’s book details how, despite having waged a multi-billion-dollar War on Cancer for nearly half a century, it is only within the past decade or so that we have truly begun to understand the complex system of cellular switching that marks the pathway leading to the disease. It’s an Olympian relay race involving a mind-boggling panoply of chemicals: genes, proteins, enzymes, hormones, and more. You can add to that an expanding array of interlopers that portend to trigger or accelerate cancer’s march, including exposures to environmental chemicals such as those contained in cigarette smoke, asbestos, and pesticides, to name just a few.
Only in the final pages of his book, after many chapters detailing early accounts of cancer, terrifyingly painful early treatments, and dozens of clinical trials, does Mukherjee turn his attention to the environmental triggers that steer cells down the path to unbridled tumorous growth. And while he acknowledges concerns that the indiscriminate overuse of pesticides and the proliferation of other chemicals in our environment may play a role, he notes that science has been slow to conclusively prove the link.
Of the various methods for determining carcinogenicity that exist, some will detect one cancer-causing agent and miss another, equally damning, substance altogether. “Scientifically speaking,” he writes, “this is an embarrassment.” But through our rapidly expanding understanding of the pathways that lead to cancer, he asserts, the next generation of molecular epidemiologists may be able to better differentiate chemicals that cause cancer from those that do not.
That, ultimately, may get us closer to one of the more modest goals that Mukherjee cites, one that involves not the eradication of cancer, but the rightful relegation of it to a disease of the very old—one that emerges only after a lifetime of natural genetic mutations rather than premature insult. “Death in old age is inevitable,” he writes, quoting the pioneering British epidemiologist Richard Doll, “but death before old age is not.”