Free The Cancer Chronicles by George Johnson Page A

anthropologists calltaphonomic changes. In digging and transporting skeletal remains, markings can inadvertently be erased. Bone-eating osteolytic lesions can cause a specimen to crumble and disappear. Through erosion, decomposition, and the gnawing of rodents, taphonomic changes might also create the illusion of metastasis—pseudopathology—a possibility that must be takeninto account along with alternative diagnoses like osteoporosis and infectious disease. But on balance it seems likely that theevidence of ancient cancer issignificantly underreported. Most skeletons, after all, are incomplete. Metastases aremore likely to appear in certain bones like the vertebrae, pelvis, femur, and skull. Others rarely are affected. No one can know if a missing bone happened to be the one that was cancerous.
    Hoping to cut through the uncertainty,Tony Waldron, a paleopathologist at University College London, tried to get a feel for how much cancer archaeologists should be expected to find. First he had to come up with an estimate, no matter how crude, of the frequency with whichprimary tumors might have occurred in earlier times. There wasn’t much to go on. The oldest records that seemed at all reliable were from the registrar general of Britain for causes of death between the years 1901 to 1905. Using that as his baseline, he took into account the likelihood that various cancers would come to roost in the skeleton, where they might be identified. The numbers, a range of approximations, came from modern autopsy reports. Forcolorectal cancer the odds were low, 6 to 11 percent, as they were forstomach cancer, 2 to 18 percent. On the high side were cancer of the breast (57 to 73 percent) and prostate (57 to 84 percent).
    From these and other considerations, Waldron calculated that (depending on age at death) the proportion of cancers in a collection of old bones would bebetween 0 and 2 percent for males and 4 and 7 percent for females. No matter how hard you looked, cases of ancient cancer would be sparse—even if the rate had been as high as that of industrial Britain. To test if his numbers were plausible, he tried them out on the remains of 623 people who had been placed in a crypt at Christ Church, Spitalfields in the East End of London between 1729 and 1857. Relying solely on visual inspection, he found one case of carcinoma among the women and none among the men. That was within the range of his formula, encouragement that it was not wildly wrong.
    The next step was to try the predictions on much older and larger populations: 905 well-preserved skeletons buried at two sites in Egyptbetween 3200 and 500 B.C. and 2,547 skeletons that had been placed in a southern German ossuary between 1400 and 1800 A.D. (The church cemetery was so small and crowded that remains, once they had decomposed, were periodically removed and put into storage.) Usingx-rays andCT scans to confirm the diagnoses, pathologists in Munich found five cancers in the Egyptian skeletons and thirteen in the German ones—about what Waldron’s calculations predicted. For all the differences between life in ancient Egypt, ReformationGermany, and early twentieth-century Britain, the frequency of cancer appeared to be about the same.
    Since then the world has grown more complex. Longevity has soared along with the manufacture of cigarettes. Diets have changed drastically and the world is awash with synthetic substances. The medical system has gotten better at detecting cancer. Epidemiologists are still trying to untangle all the threads. Yet running beneath the surface there is a core rate of cancer, the legacy of being multicellular creatures in an imperfect world. There is no compelling evidence that this baseline is much different now than it was in ancient times.
    While still immersed in the arcana of paleo-oncology, I had dinner with a friend, a scientist in her thirties who had recently been treated forbreast cancer. Like many people she suspected that there is far