The Truth about Cancer

EVERY New Year when the government publishes its Report to the Nation on the Status of Cancer, it is followed by a familiar lament. We are losing the war against cancer. Half a century ago, the story goes, a person was far more likely to die from heart disease. Now cancer is on the verge of overtaking it as the No. 1 cause of death. Troubling as this sounds, the comparison is unfair. Cancer is, by far, the harder problem — a condition deeply ingrained in the nature of evolution and multicellular life. Given that obstacle, cancer researchers are fighting and even winning smaller battles: reducing the death toll from childhood cancers and preventing — and sometimes curing — cancers that strike people in their prime. But when it comes to diseases of the elderly, there can be no decisive victory. This is, in the end, a zero-sum game.

The rhetoric about the war on cancer implies that with enough money and determination, science might reduce cancer mortality as dramatically as it has with other leading killers — one more notch in medicine’s belt. But what, then, would we die from? Heart disease and cancer are primarily diseases of aging. Fewer people succumbing to one means more people living long enough to die from the other. The newest cancer report, which came out in mid-December, put the best possible face on things. If one accounts for the advancing age of the population — with the graying of the baby boomers, death itself is on the rise — cancer mortality has actually been decreasing bit by bit in recent decades. But the decline has been modest compared with other threats. A graph from the Centers for Disease Control and Prevention tells the story. There are two lines representing the age-adjusted mortality rate from heart disease and from cancer. In 1958 when the diagram begins, the line for heart disease is decisively on top. But it plunges by 68 percent while cancer declines so slowly — by only about 10 percent — that the slope appears far less significant.

Measuring from 1990, when tobacco had finished the worst of its damage and cancer deaths were peaking, the difference is somewhat less pronounced: a decline of 44 percent for heart disease and 20 percent for cancer. But as the collision course continues, cancer seems insistent on becoming the one left standing — death’s final resort.n, the result of a basic evolutionary compromise. As a body lives and grows, its cells are constantly dividing, copying their DNA — this vast genetic library — and bequeathing it to the daughter cells. They in turn pass it to their own progeny: copies of copies of copies. Along the way, errors inevitably occur. Some are caused by carcinogens but most are random misprints. Over the eons, cells have developed complex mechanisms that identify and correct many of the glitches. But the process is not perfect, nor can it ever be. Mutations are the engine of evolution. Without them we never would have evolved. The trade-off is that every so often a certain combination will give an individual cell too much power. It begins to evolve independently of the rest of the body. Like a new species thriving in an ecosystem, it grows into a cancerous tumor. For that there can be no easy fix. These microscopic rebellions have been happening for at least half a billion years, since the advent of complex multicellular life — collectives of cells that must work together, holding back, as best each can, the natural tendency to proliferate. Those that do not — the cancer cells — are doing, in a Darwinian sense, what they are supposed to do: mutating, evolving and increasing in fitness compared with their neighbors, the better behaved cells of the body. And these are left at a competitive disadvantage, shackled by a compulsion to obey the rules.
George Johnson is a former reporter and editor at The New York Times