Men Have Higher Lifetime Ca Risk Than Women: SEER Data

BETHESDA, Md--The lifetime risk of developing cancer for the USpopulation is 44.8% for men and 39.3% for women, according toan analysis of incidence rates from the National Cancer Institute'sSEER (Surveillance Epidemiology and End Results) program for 1973to 1991.

Risks of developing cancer are higher in whites than in blacksby about 8%, said Lawrence Garfinkel, special consultant in epidemiologyand statistics, American Cancer Society.

However, lifetime risks of dying of cancer show smaller differencesbetween sexes and races. Among men, 23.4% will die of cancer,compared with 20.4% of women, and the risk of dying of canceris the same in whites and blacks (23.6% vs 23% for white and blackmen, respectively, and 20.8% vs 19% for white and black women,respectively).

For men, prostate cancer, at 15.4%, tops the list of cancers mostlikely to develop in a lifetime, while for women, breast cancerrepresents the most likely cancer with a 12.3% lifetime risk (onein eight).

Other cancers with a high lifetime probability include lung andbronchus (8.5% for men and 5.2% for women) and colorectal (6.1%for men and 5.9% for women). All other cancers, except for urinarybladder cancer in men (3.3%), have a lifetime risk of under 2%for both sexes. Of those sites that can be compared, men havea higher risk of developing cancer than women at all sites, exceptfor the pancreas, thyroid, and breast.

For both sexes, lung cancer represents the most life-threateningcancer, with risk of dying of the disease at 7.1% for men and4.1% for women, Mr. Garfinkel said in his report in the StatisticalBulletin (Oct-Dec 1995, pp 31-37).

Cancer Occurs Earlier in Women

For men, the probability of developing cancer of any site is relativelylow up to age 40. "Even by age 70, the probability is only20.6%," Mr. Garfinkel said. "It is only later in lifethat the risk of a man eventually developing cancer approaches50%."

Among women, cancer tends to occur earlier than for men in certainsites. Even though a woman's risk is lower than a man's at eachage interval, her risk is greater for shorter periods of timeat certain ages.

"For example, for women age 30, the risk of developing cancerof any site is 1.2 in the next 10 years versus 1.0 for men,"he said. "Over the next 20 years, a 30-year-old woman hasa risk of 4.4 compared with 2.9 for men."

Mr. Garfinkel pointed out that these are overall risk, with muchhigher risks for those who smoke cigarettes, are exposed to toxicchemicals, or have a family history of cancer. He concludes witha warning: "The reports of increasing proportions of youngpersons initiating the smoking habit are particularly troublesomebecause the results of smoking prevention have potentially thegreatest effect on reducing cancer mortality."

Calculating Lifetime Cancer Risks

To determine the lifetime risk of dying of cancer, the researchersets up a hypothetical population of 10 million at age 0, andthen, based on incidence or mortality rates from SEER data, calculatesthe number of people who develop or die of cancer in each 5-yearage interval, the number who die of other causes, and the numberwho survive the 5-year age interval.

It is then also possible to define the probability of developingor dying of cancer at any given age over the next 10, 20, 30 years,or more.