July 12, 2011 -- Men are more likely than women to die of cancer in the U.S., a new study shows.
"Our research suggests that the main factor driving greater frequency of cancer deaths in men is the greater frequency of cancer diagnosis, rather than poorer survival once the cancer occurs," says study researcher Michael B. Cook, PhD, BsC, of the National Cancer Institute.
The study is published in Cancer Epidemiology, Biomarkers & Prevention.
Cook says that if investigators "can identify the causes of these gender differences in cancer incidence, then we can take preventative actions to reduce the cancer burden in both men and women."
Cook and his research team analyzed U.S. data from a large database that contained statistics on 36 cancers by age and sex for the period of 1977 to 2006.
For "the vast majority" of the cancers, rates were higher among men than women, the researchers write.
The highest male-to-female death rate ratios were 5.51 men for every woman for lip cancer, 5.37 to 1 for cancer of the larynx, and 4.47 to 1 for cancer of the hypopharynx (a type of throat cancer).
The male-female death rate ratio for cancer of the esophagus was 4.08 to 1, and 3.36 to 1 for urinary bladder cancer.
Many cancers with the highest overall death rates also showed greater death risk for men than women. The male-female ratios for lung cancer were 2.31 to 1, for colorectal cancer 1.42 to 1, and 1.37 to 1 for pancreatic cancer.
For leukemia, the male-female ratio was 1.75 to 1, and for liver and intrahepatic bile duct cancer the ratio was 2.23 to 1.
5-Year Survival Rates
Researchers analyzed the five-year survival rate of people with many types of cancer. Men had poorer survival than women for most, but the researchers say they could not assign a "singular root cause."
However, differences in screening of people without symptoms, the presence of other illnesses or health care behaviors, and differences in the behavior of the cancer may be factors in the higher male-to-female death rate for cancer, according to the researchers.
Three cancers had a higher death rate in women than men: gallbladder cancer, anal cancer, and cancer of the peritoneum, omentum, and mesentery.
Cook tells WebMD in an email that the reason for the difference in mortality rates is "not clear cut."
"For many cancer sites, male and female incidence rates have changed disproportionately over time, and this implies that the root cause of sex differences in cancer incidence rates, and by extension cancer mortality rates, are sex differences in tobacco smoking and viral infections, anti-oxidative capacity and hormones and metal toxicity."
The researchers state that future studies should focus on the factors responsible for greater rates of diagnosis of cancer among men.