Women have a better survival rate than men in early stage lung cancers, regardless of treatment or even lack of treatment. The findings, from a nearly 10-year review of Medicare records, were presented here at the annual meeting of the American College of Chest Physicians.
Dr. Juan P. Wisnievsky and colleagues at Mt. Sinai School of Medicine in New York collected a population-based sample from the Surveillance, Epidemiology and End Results registry derived from Medicare data between 1991 and 1999.
The investigators reviewed 18,967 cases of early lung cancer, and grouped patients into four groups: those receiving radiation; surgery; chemotherapy or no treatment. The team then accounted for other medical problems and competing causes of death in the patients.
Lung cancer usually occurs because some outside factor, called a carcinogen, has triggered the growth of abnormal, cancerous cells in the lung. These cancerous cells multiply out of control and eventually form a mass called a tumor. As the tumor grows, it destroys nearby areas of the lung. Eventually, the tumor’s abnormal cells can spread (metastasize) to nearby lymph nodes and to distant organs, such as the brain. In most cases, the carcinogens that trigger lung cancer are chemicals found in cigarette smoke.
Lung cancers are divided into two basic groups, non-small-cell lung cancer and small-cell lung cancer, based on the microscopic appearance of the tumor cells. These two groups are treated differently.
Wisnievsky reported that women in all four groups had better survival than men, with a five-year lung cancer-related survival rate of 53 percent for women and 40 percent for men. What was most striking, he said, was that among those receiving no treatment, women had a 25 percent decrease risk of death at five years compared to men.
The better survival among untreated women “suggests that lung cancer in women has a different intrinsic biological behavior and natural history than in men,” Wisnievsky told Reuters Health.
The New York investigator said that the survival difference may result from genetic, metabolic and hormonal differences. He noted that estrogen receptors have recently been found on lung cancer cells.
He said the results “should affect the design and analysis of clinical trials ... which may benefit from stratification by sex, and may be incorporated into prognostic classifications.”
In addition to considerations of prognostic classifications, Wisnievsky noted that the findings may also affect treatment choices based on gender.
Revision date: July 8, 2011
Last revised: by Jorge P. Ribeiro, MD