The cancer mortality rate - the percentage of the U.S. population that dies from cancer each year - peaked at the beginning of this decade after increasing every year since the 1930s, when nationwide records were first collected systematically, researchers found. Beginning in 1991, the cancer mortality rate has dropped annually from a 1990 high of about 135 deaths a year per 100,000 people to 130.8 per 100,000 in 1995.
That does not necessarily mean that the total number of Americans dying of cancer will diminish in the near future. That's because the size of the U.S. population is increasing and the elderly - who are more prone to many cancers - make up an ever larger proportion of society. In addition, the incidence of cancer - the number of people being diagnosed with cancer - has continued to increase slightly, for reasons that are largely unknown.
Nonetheless, in the short term, the fall in the death rate means that at least 12,000 and possibly as many as 16,000 Americans will survive cancer this year who would have died if the rates were the same as they were in 1990, according to Harmon Eyre, chief medical officer of the American Cancer Society.
Experts attributed the dropping mortality rate in large part to the decrease in smoking, although a drop in drinking, exposure to the sun, and exposures to chemicals in the workplace also played a role. In addition, improved early-detection methods and new medical treatments have improved cancer survival rates, they said.
The new findings arise from two independent but complementary studies by academic researchers and staff of the National Cancer Institute.
Philip Cole and Brad Rodu of the University of Alabama at Birmingham, whose analysis is being published in the Nov. 15 issue of the ACS journal Cancer, conclude that total mortality rates from all forms of cancer hit a plateau in 1990, and fell by about 3.1 percent from 1990 to 1995. That means a drop in death rates of about 4.2 cases per hundred thousand person-years - about 40 percent of which, they determined, is attributable to decreases in lung cancer fatality.
Cole and Rodu based their conclusions on examination of three nationwide data sets: the federal government's Vital Statistics of the United States; the Center for Disease Control and Prevention's monthly mortality reports; and fatality information from NCI's broad-based national surveillance program.
While Cole and Rodu were preparing their report, NCI researchers involved in a separate review of national cancer fatality figures were coming to a similar conclusion. NCI's final report is due in 1997. But in a summary released yesterday, NCI stated that it, too, had discerned an approximately 3-percent drop in death rates from 1990 to 1995.
Most of it, the summary said, "is due to declines in lung, colorectal and prostate cancer deaths in men, and breast, colorectal and gynecologic cancer deaths in women.''
Statistically, African Americans benefited most from the mortality-rate improvements, NCI found. From 1991 to 1995, the overall cancer death rate among white Americans dropped by 1.7 percent. But the mortality rate for all cancer sites combined declined 5.6 percent among blacks, in sharp contrast to an 18.3 percent rise in the rate between 1971 and 1990, the NCI found. Much of that reduction "is due to a 10 percent decline in lung cancer deaths among black men, which account for one-third of all cancer deaths in black men,'' the NCI stated.
The NCI researchers noted that the death rate for certain cancers and certain groups have continued to increase despite the overall decline. In men, mortality from lymphatic cancers has risen, for example; so have lung cancer deaths in women aged 65 and older.