Cancer rates aren’t rapidly rising. But this complicated disease is proving to be harder to combat than heart disease.
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.
As 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 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. 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. (The wild card in the equation is death from complications of Alzheimer’s disease, which has been advancing year after year.)
Though not exactly consoling, the fact that we have reached this standoff is a kind of success.
A century ago, average life expectancy at birth was in the low to mid-50s. Now it is almost 79, and if you make it to 65 you’re likely to live into your mid-80s. The median age of cancer death is 72. We live long enough for it to get us.
The diseases that once killed earlier in life — bubonic plague, smallpox, influenza, tuberculosis — were easier obstacles. For each there was a single infectious agent, a precise cause that could be confronted. Even AIDS is being managed more and more as a chronic condition.
Progress against heart disease has been slower. But the toll has been steadily reduced, or pushed further into the future, with diet, exercise and medicines that help control blood pressure and cholesterol. When difficulties do arise, they can often be treated as mechanical problems — clogged piping, worn-out valves — for which there may be a temporary fix.
Because of these interventions, people between 55 and 84 are increasingly more likely to die from cancer than from heart disease. For those who live beyond that age, heart disease gains the upper hand. But year by year, as more failing hearts can be repaired or replaced, cancer has been slowly closing the gap.
For the oldest among us, the two killers are fighting to a draw.
But there are reasons to believe that cancer will remain the most resistant. It is not so much a disease as a phenomenon, the result of a basic evolutionary compromise. As a body lives and grows, its cells are constantly dividing, copying their DNA 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.