Cancer is above all an age thing. Between birth and the age of forty, men have just a one in seventy-one chance of getting cancer and women one in fifty-one, but over sixty the odds drop to one in three for men and one in four for women. An eighty-year-old person is a thousand times more likely than a teenager to develop cancer.
Lifestyle is a huge factor in determining which of us get cancer. More than half of cases, by some calculations, are caused by things we can do something about—smoking, drinking to excess, and overeating primarily. The American Cancer Society found a “significant association” between being overweight and incidence of cancer of the liver, breast, esophagus, prostate, colon, pancreas, kidney, cervix, thyroid, and stomach—just about everywhere, in short. How exactly weight tips the balance is not at all understood, but it certainly seems to.
Environmental exposures are also a significant source of cancers—more perhaps than most of us realize. The first person to notice a connection between environment and cancers was a British surgeon, Percivall Pott, who in 1775 noted that scrotal cancer was disproportionately prevalent among chimney sweeps—indeed, was so particular to the profession that the disorder was called chimney sweep’s cancer. Pott’s investigation into their plight, in a work called Chirurgical Observations: Relative to the Cataract, the Polypus of the Nose, the Cancer of the Scrotum, the Different Kinds of Ruptures, and the Mortification of the Toes and Feet, was notable not only for identifying an environmental source for a cancer but in showing some compassion for the poor chimney sweeps, for even in that hard and neglectful age they were a forlorn group. From earliest childhood, Pott recorded, sweeps were “frequently treated with great brutality, and almost starved with cold and hunger; they are thrust up narrow and sometimes hot chimnies, where they are bruised, burned, and almost suffocated; and when they get to puberty, become peculiarly liable to a most noisome, painful, and fatal disease.” The cause of the cancer, Pott discovered, was an accumulation of soot in the sweeps’ scrotal folds. A good wash once a week stopped the cancer from arising, but most sweeps didn’t get a weekly wash, and scrotal cancer remained a problem until late in the nineteenth century.
No one knows, because it is essentially impossible to determine, to what extent environmental factors contribute to cancers now. More than eighty thousand chemicals are produced commercially in the world today, and by one calculation 86 percent of them have never been tested for their effects on humans. We don’t even know much about the good or neutral chemicals around us. As Pieter Dorrestein of the University of California at San Diego told a journalist from the journal Chemistry World in 2016, “If one asks the question what are the ten most abundant molecules in the human habitat, no one can answer.” Of the things that might harm us, only radon, carbon dioxide, tobacco smoke, and asbestos have been studied really extensively. The rest is mostly speculation. We inhale a lot of formaldehyde, which is used in flame retardants and the glues that hold together our furniture. We also produce and breathe in a lot of nitrogen dioxide, polycyclic hydrocarbons, semi-organic compounds, and miscellaneous particulates. Even the cooking of food and the burning of candles can throw off particulates that may do us no good at all. Although no one can say to what extent pollutants in air and water contribute to cancers, it has been estimated that it may be as much as 20 percent.
Viruses and bacteria cause cancers, too. The World Health Organization in 2011 estimated that 6 percent of cancers in the developed world but 22 percent in low- and middle-income countries are attributable to viruses alone. This was once a very radical idea. In 1911, when Peyton Rous, a recently qualified researcher at the Rockefeller Institute in New York, found that a virus caused cancer in chickens, the discovery was universally dismissed. In the face of opposition and even some ridicule, Rous dropped the idea and turned to other research. It was not until 1966, more than half a century after his discovery, that he was formally vindicated with the award of a Nobel Prize. We now know that pathogens are responsible for cervical cancer (caused by the human papillomavirus), Burkitt’s lymphoma, hepatitis B and C, and several others. Altogether, it has been estimated, pathogens may account for a quarter of all cancers globally.*2
And sometimes cancer just seems to be cruelly random. About 10 percent of men and 15 percent of women who get lung cancer are not smokers, have not been exposed to known environmental hazards, or have not faced any other increased risks, as far as can be told. They are just, it seems, very, very unlucky, but whether they are unlucky in a fateful sense or a genetic one is usually impossible to say.
One thing is common to all cancers, however. Treatment is rough.
II
IN 1810, THE English novelist Fanny Burney, while living in France, developed breast cancer at the age of fifty-eight. It is almost impossible to imagine how horrifying this must have been. Two hundred years ago, every form of cancer was horrible, but breast cancer especially so. Most victims suffered years of torment and often unspeakable embarrassment as a tumor slowly devoured their breast and replaced it with an open hole from which seeped foul fluids that made it impossible for the poor victim to mix with others, sometimes even with her own family. Surgery was the only possible treatment, but in the days before anesthetics it was at least as painful and distressing as the cancer itself and was nearly always lethal.
Burney was told that her only hope was to undergo a mastectomy. She recounted the ordeal—“a terror that surpasses all description”—in a letter to her sister Esther. Even now it makes painful reading. On a September afternoon, Burney’s surgeon, Antoine Dubois, came to her house with six assistants—four other doctors and two students. A bed had been moved to the middle of the room and space around it cleared for the team to work.
“M. Dubois placed me upon the mattress, and spread a cambric handkerchief upon my face,” Burney reported to her sister. “It was transparent, however, and I saw through it that the bedstead was instantly surrounded by seven men and my nurse. I refused to be held; but when, bright through the cambric, I saw the glitter of polished steel—I closed my eyes. When the dreadful steel was plunged into the breast—cutting through veins—arteries—flesh—nerves—I needed no injunctions to restrain my cries. I began a scream that lasted intermittingly during the whole time of the incision—and I almost marvel that it rings not in my ears still, so excruciating was the agony….I felt the instrument—describing a curve—cutting against the grain, if I may say so, while the flesh resisted in a manner so forcible as to oppose and tire the hand of the operator, who was forced to change from the right to the left—then, indeed, I thought I must have expired. I attempted no more to open my eyes.”
She thought the surgery was over, but Dubois found that the breast was still attached by the tumor, so cutting recommenced. “Oh heaven! I then felt the knife rackling against the breast bone—scraping it!” For some minutes, the surgeon cut away at muscle and diseased tissue until he was confident that he had got as much as he could. Burney endured this final part in silence—“in utterly speechless torture.”