Siddhartha Mukherjee - The Emperor of All Maladies: A Biography of Cancer

by Siddhartha Mukherjee

  A link between an ancient antigen and cirrhosis suggested a genetic susceptibility for liver disease--a theory that would have sent Blumberg off on a long and largely fruitless tangent. But a chance incident overturned that theory and radically changed the course of Blumberg's studies. The lab had been following a young patient at a mental-disability clinic in New Jersey. Initially, the man had tested negative for the Au antigen. But during one of the serial blood draws in the summer of 1966, his serum suddenly converted from "Au negative" to "Au positive." When his liver function was measured, an acute, fulminant hepatitis was discovered.

  But how could an "intrinsic" gene cause sudden seroconversion and hepatitis? Genes, after all, do not typically flicker on and off at will. Blumberg's beautiful theory about genetic variation had been slain by an ugly fact. Au, he realized, could not mark an inherent variation in a human gene. In fact, Au was soon found to be neither a human protein nor a blood antigen. Au was a piece of a viral protein floating in the blood, the sign of an infection. The New Jersey man had been infected by this microbe and thus converted from Au negative to positive.

  Blumberg now raced to isolate the organism responsible for the infection. By the early 1970s, working with a team of collaborators, his lab had purified particles of a new virus, which he called hepatitis B virus, or HBV. The virus was structurally simple--"roughly circular . . . about forty-two nanometers in diameter, one of the smallest DNA viruses that infect humans"--but the simple structure belied extraordinarily complex behavior. In humans, HBV infection caused a broad spectrum of diseases, ranging from asymptomatic infection to acute hepatitis to chronic cirrhosis in the liver.

  The identification of a new human virus set off a storm of activity for epidemiologists. By 1969, Japanese researchers (and subsequently Blumberg's group) had learned that the virus was transmitted from one individual to another through blood transfusions. By screening blood before transfusion--using the now familiar Au antigen as one of the early biomarkers in serum--the blood-borne infection could be blocked, thereby reducing the risk of hepatitis B.

  But another illness soon stood out as linked to HBV: a fatal, insidious form of liver cancer endemic in parts of Asia and Africa that arose out of scarred, ashen livers often decades after chronic viral infection. When cases of hepatocellular cancer were compared to controls using classical statistical methods, chronic infection with HBV, and the associated cycle of injury and repair in liver cells, stood out as a clear risk factor--at about five- to tenfold the risk for uninfected controls. HBV, then, was a carcinogen--although a live carcinogen, capable of being transmitted from one host to another.

  The discovery of HBV was an embarrassment to the NCI. The institute's highly targeted and heavily funded Special Virus Cancer Program, having inoculated thousands of monkeys with human cancer extracts, had yet to find a single cancer-associated virus. Yet a genetic anthropologist exploring aboriginal antigens had found a highly prevalent virus associated with a highly prevalent human cancer. Blumberg was acutely aware of the NCI's embarrassment, and of the serendipity in his work. His departure from the NIH in 1964, although cordial, had been driven by precisely such conflicts; his interdisciplinary curiosity had chafed against the "discipline-determined rigidity of the constituent institutes," among which the NCI, with its goal-directed cancer virus hunt, was the worst culprit. Worse still for the strongest enthusiasts of the cancer virus theory, it appeared as if Blumberg's virus itself was not the proximal cause of the cancer. The inflammation induced by the virus in liver cells, and the associated cycle of death and repair, appeared to be responsible for the cancer--a blow to the notion that viruses directly cause cancer.

  But Blumberg had little time to mull over these conflicts, and he certainly had no theoretical axes to grind about viruses and cancer. A pragmatist, he directed his team toward finding a vaccine for HBV. By 1979, his group had devised one. Like the blood-screening strategy, the vaccine did not, of course, alter the course of the cancer after its genesis, but it sharply reduced the susceptibility to HBV infection in uninfected men and women. Blumberg had thus made a critical link from cause to prevention. He had identified a viral carcinogen, found a method to detect it before transmission, then found a means to thwart transmission.

  The strangest among the newly discovered "preventable" carcinogens, though, was not a virus or a chemical but a cellular organism--a bacterium. In 1979, the year that Blumberg's hepatitis B vaccine was beginning its trial in America, a junior resident in medicine named Barry Marshall and a gastroenterologist, Robin Warren, both at the Royal Perth Hospital in Australia, set out to investigate the cause of stomach inflammation, gastritis, a condition known to predispose patients to peptic ulcers and to stomach cancer.

  For centuries, gastritis had rather vaguely been attributed to stress and neuroses. (In popular use, the term dyspeptic still refers to an irritable and fragile psychological state.) By extension, then, cancer of the stomach was cancer unleashed by neurotic stress, in essence a modern variant of the theory of clogged melancholia proposed by Galen.

  But Warren had convinced himself that the true cause of gastritis was a yet unknown species of bacteria, an organism that, according to dogma, could not even exist in the inhospitable acidic lumen of the stomach. "Since the early days of medical bacteriology, over one hundred years ago," Warren wrote, "it was taught that bacteria do not grow in the stomach. When I was a student, this was taken as so obvious as to barely rate a mention. It was a 'known fact,' like 'everyone knows that the earth is flat.'"

  But the flat-earth theory of stomach inflammation made little sense to Warren. When he examined biopsies of men and women with gastritis or gastric ulcers, he found a hazy, blue layer overlying the craterlike depressions of the ulcers in the stomach. When he looked even harder at that bluish layer, he inevitably saw spiral organisms teeming within it.

  Or had he imagined it? Warren was convinced that these organisms represented a new species of bacterium that caused gastritis and peptic ulcers. But he could not isolate the bacteria in any form on a plate, dish, or culture. Others could not see the organism; Warren could not grow it; the whole theory, with its blue haze of alien organisms growing above craters in the stomach, smacked of science fiction.

  Barry Marshall, in contrast, had no pet theory to test or disprove. The son of a Kalgoorlie boilermaker and a nurse, he had trained in medicine in Perth and was an unwhetted junior investigator looking for a project. Intrigued by Warren's data (although skeptical of the link with an unknown, phantasmic bacteria), he started to collect brushings from patients with ulcers and spread out the material on petri dishes, hoping to grow a bacterium. But as with Warren, no bacteria grew out. Week after week, Marshall's dishes piled up in the incubator and were discarded in large stacks after a few days of examination.

  But then serendipity intervened: over an unexpectedly busy Easter weekend in 1982, with the hospital overflowing with medical admissions, Marshall forgot to examine his plates and left them in the incubator. When he remembered and returned to examine them, he found tiny, translucent pearls of bacterial colonies growing on the agar. The long incubation period had been critical. Under the microscope, the bacterium growing on the plate was a minuscule, slow-growing, fragile organism with a helical tail, a species that had never been described by microbiologists. Warren and Marshall called it Helicobacter pylori--helicobacter for its appearance, and pylorus from the Latin for "gatekeeper," for its location near the outlet valve of the stomach.

  But the mere existence of the bacteria, or even its association with ulcers, was not proof enough that it caused gastritis. Koch's third postulate stipulated that to be classified as a bona fide causal element for a disease, an organism needed to re-create the disease when introduced into a naive host. Marshall and Warren inoculated pigs with the bacteria and performed serial endoscopies. But the pigs--seventy pounds of porcine weight that did not take kindly to weekly endoscopies--did not sprout any ulcers. And testing the theory on humans was ethi
cally impossible: how could one justify infecting a human with a new, uncharacterized species of bacteria to prove that it caused gastritis and predisposed to cancer?

  In July 1984, with his experiments stalled and his grant applications in jeopardy, Marshall performed the ultimate experiment: "On the morning of the experiment, I omitted my breakfast. . . . Two hours later, Neil Noakes scraped a heavily inoculated 4 day culture plate of Helicobacter and dispersed the bacteria in alkaline peptone water (a kind of meat broth used to keep bacteria alive). I fasted until 10 am when Neil handed me a 200 ml beaker about one quarter full of the cloudy brown liquid. I drank it down in one gulp then fasted for the rest of the day. A few stomach gurgles occurred. Was it the bacteria or was I just hungry?"

  Marshall was not "just hungry." Within a few days of swallowing the turbid bacterial culture, he was violently ill, with nausea, vomiting, night sweats, and chills. He persuaded a colleague to perform serial biopsies to document the pathological changes, and he was diagnosed with highly active gastritis, with a dense overlay of bacteria in his stomach and ulcerating craters beneath--precisely what Warren had found in his patients. In late July, with Warren as coauthor, Marshall submitted his own case report to the Medical Journal of Australia for publication ("a normal volunteer [has] swallowed a pure culture of the organism," he wrote). The critics had at last been silenced. Helicobacter pylori was indisputably the cause of gastric inflammation.

  The link between Helicobacter and gastritis raised the possibility that bacterial infection and chronic inflammation caused stomach cancer.* Indeed, by the late 1980s, several epidemiological studies had linked H. pylori-induced gastritis with stomach cancer. Marshall and Warren had, meanwhile, tested antibiotic regimens (including the once-forsaken alchemical agent bismuth) to create a potent multidrug treatment for the H. pylori infection.* Randomized trials run on the western coast of Japan, where stomach and H. pylori infection are endemic, showed that antibiotic treatment reduced gastric ulcers and gastritis.

  The effect of antibiotic therapy on cancer, though, was more complex. The eradication of H. pylori infection in young men and women reduced the incidence of gastric cancer. In older patients, in whom chronic gastritis had smoldered for several decades, eradication of the infection had little effect. In these elderly patients, presumably the chronic inflammation had already progressed to a point that its eradication made no difference. For cancer prevention to work, Auerbach's march--the prodrome of cancer--had to be halted early.

  Although unorthodox in the extreme, Barry Marshall's "experiment"--swallowing a carcinogen to create a precancerous state in his own stomach--encapsulated a growing sense of impatience and frustration among cancer epidemiologists. Powerful strategies for cancer prevention arise, clearly, from a deep understanding of causes. The identification of a carcinogen is only the first step toward that understanding. To mount a successful strategy against cancer, one needs to know not only what the carcinogen is, but what the carcinogen does.

  But the set of disparate observations--from Blumberg to Ames to Warren and Marshall--could not simply be stitched together into a coherent theory of carcinogenesis. How could DES, asbestos, radiation, hepatitis virus, and a stomach bacterium all converge on the same pathological state, although in different populations and in different organs? The list of cancer-causing agents seemed to get--as another swallower of unknown potions might have put it--"curiouser and curiouser."

  There was little precedent in other diseases for such an astonishing diversity of causes. Diabetes, a complex illness with complex manifestations, is still fundamentally a disease of abnormal insulin signaling. Coronary heart disease occurs when a clot, arising from a ruptured and inflamed atherosclerotic plaque, occludes a blood vessel of the heart. But the search for a unifying mechanistic description of cancer seemed to be sorely missing. What, beyond abnormal, dysregulated cell division, was the common pathophysiological mechanism underlying cancer?

  To answer this question, cancer biologists would need to return to the birth of cancer, to the very first steps of a cell's journey toward malignant transformation--to carcinogenesis.

  *H. pylori infection is linked to several forms of cancer, including gastric adenocarcinoma and mucosa-associated lymphoma.

  *Marshall later treated himself with the regimen and eradicated his infection.

  "A spider's web"

  It is to earlier diagnosis that we must look for any material improvement in our cancer cures.

  --John Lockhart-Mummery, 1926

  The greatest need we have today in the human cancer problem, except for a universal cure, is a method of detecting the presence of cancer before there are any clinical signs of symptoms.

  --Sidney Farber, letter to Etta Rosensohn,

  November 1962

  Lady, have you been "Paptized"?

  --New York Amsterdam News,

  on Pap smears, 1957

  The long, slow march of carcinogenesis--the methodical, step-by-step progression of early-stage lesions of cancer into frankly malignant cells--inspired another strategy to prevent cancer. If cancer truly slouched to its birth, as Auerbach suspected, then perhaps one could still intervene on that progression in its earliest stages--by attacking precancer rather than cancer. Could one thwart the march of carcinogenesis in midstep?

  Few scientists had studied this early transition of cancer cells as intensively as George Papanicolaou, a Greek cytologist at Cornell University in New York. Robust, short, formal, and old-worldly, Papanicolaou had trained in medicine and zoology in Athens and in Munich and arrived in New York in 1913. Penniless off the boat, he had sought a job in a medical laboratory but had been relegated to selling carpets at the Gimbels store on Thirty-third Street to survive. After a few months of truly surreal labor (he was, by all accounts, a terrible carpet salesman), Papanicolaou secured a research position at Cornell that may have been just as surreal as carpet selling: he was assigned to study the menstrual cycle of guinea pigs, a species that neither bleeds visibly nor sheds tissue during menses. Using a nasal speculum and Q-tips, Papanicolaou had nonetheless learned to scrape off cervical cells from guinea pigs and spread them on glass slides in thin, watery smears.

  The cells, he found, were like minute watch-hands. As hormones rose and ebbed in the animals cyclically, the cells shed by the guinea pig cervix changed their shapes and sizes cyclically as well. Using their morphology as a guide, he could foretell the precise stage of the menstrual cycle often down to the day.

  By the late 1920s, Papanicolaou had extended his technique to human patients. (His wife, Maria, in surely one of the more grisly displays of conjugal fortitude, reportedly allowed herself to be tested by cervical smears every day.) As with guinea pigs, he found that cells sloughed off by the human cervix could also foretell the stages of the menstrual cycle in women.

  But all of this, it was pointed out to him, amounted to no more than an elaborate and somewhat useless invention. As one gynecologist archly remarked, "in primates, including women," a diagnostic smear was hardly needed to calculate the stage or timing of the menstrual cycle. Women had been timing their periods--without Papanicolaou's cytological help--for centuries.

  Disheartened by these criticisms, Papanicolaou returned to his slides. He had spent nearly a decade looking obsessively at normal smears; perhaps, he reasoned, the real value of his test lay not in the normal smear, but in pathological conditions. What if he could diagnose a pathological state with his smear? What if the years of staring at cellular normalcy had merely been a prelude to allow him to identify cellular abnormalities?

  Papanicolaou thus began to venture into the world of pathological conditions, collecting slides from women with all manners of gynecological diseases--fibroids, cysts, tubercles, inflammations of the uterus and cervix, streptococcal, gonococcal, and staphylococcal infections, tubal pregnancies, abnormal pregnancies, benign and malignant tumors, abscesses and furuncles, hoping to find some pathological mark in the exfoliated cells.

 
; Cancer, he found, was particularly prone to shedding abnormal cells. In nearly every case of cervical cancer, when Papanicolaou brushed cells off the cervix, he found "aberrant and bizarre forms" with abnormal, bloated nuclei, ruffled membranes, and shrunken cytoplasm that looked nothing like normal cells. It "became readily apparent," he wrote, that he had stumbled on a new test for malignant cells.

  Thrilled by his results, Papanicolaou published his method in an article entitled "New Cancer Diagnosis" in 1928. But the report, presented initially at an outlandish "race betterment" eugenics conference, generated only further condescension from pathologists. The Pap smear, as he called the technique, was neither accurate nor particularly sensitive. If cervical cancer was to be diagnosed, his colleagues argued, then why not perform a biopsy of the cervix, a meticulous procedure that, even if cumbersome and invasive, was considered far more precise and definitive than a grubby smear? At academic conferences, experts scoffed at the crude alternative. Even Papanicolaou could hardly argue the point. "I think this work will be carried a little further," he wrote self-deprecatingly at the end of his 1928 paper. Then, for nearly two decades, having produced two perfectly useless inventions over twenty years, he virtually disappeared from the scientific limelight.

  Between 1928 and 1950, Papanicolaou delved back into his smears with nearly monastic ferocity. His world involuted into a series of routines: the daily half-hour commute to his office with Maria at the wheel; the weekends at home in Long Island with a microscope in the study and a microscope on the porch; evenings spent typing reports on specimens with a phonograph playing Schubert in the background and a glass of orange juice congealing on his table. A gynecologic pathologist named Herbert Traut joined him to help interpret his smears. A Japanese fish and bird painter named Hashime Murayama, a colleague from his early years at Cornell, was hired to paint watercolors of his smears using a camera lucida.