Gender Gaps in Lung Cancer, Even for Never-Smokers
Lung cancer is the leading cause of cancer deaths among men and women, as well as the cancer most tightly linked to smoking. According to an article published in the Journal of Clinical Oncology, 85% to 90% of all lung cancer patients have smoked cigarettes at some point in their lives. The disease can take decades to develop, often showing up years after a smoker has quit. And despite the 38% reduction in the smoking rate among women from 1965 to 2000, the prevalence of lung cancer among women grew sixfold from 1950 to 2000. Men are still more likely than women to be diagnosed with lung cancer or die of it. They are less likely than women to have never smoked, but the gender gap is narrowing.
In 1976, the odds that a woman would be diagnosed with lung cancer in a year were 1 in 3,663. The odds for a man were 1 in 1,066. By 2006 the lung cancer diagnosis odds for a man dropped slightly to 1 in 1,403 and shot up for women to 1 in 1,937.
Deaths from lung cancer showed a similar shift that was sharper for women. In 1976, the odds a woman would die of lung cancer in a year were 1 in 5,263, compared to 1 in 1,274 for a man. In 2006, the odds for a woman were 1 in 2,489 and for a man were 1 in 1,483.
But what about the person who has never smoked who gets lung cancer? Are women at greater risk than men? Some studies of never-smokers with lung cancer do indicate greater vulnerability among women. According to data from the Nurse’s Health Study, the odds a woman 40-79 who has never been a smoker will be diagnosed with lung cancer in a year are 1 in 6,579. Data from the Health Professionals Follow-Up Study shows the odds a man in the same age group who has never been a smoker will be diagnosed with lung cancer in a year are 1 in 8,929. In addition, women account for 63% of the 3,060 annual lung cancer deaths attributed to secondhand smoke.
Without smoking to blame, what's at work? Numerous studies believe the answer may lie in the hormone estrogen, which has been implicated in breast cancer but only recently considered a factor in lung cancer. Other researchers have found that genetic and/or metabolic differences between men and women may be responsible.
Some gender differences tip toward women. The odds a male will be diagnosed with lung cancer in his lifetime are 1 in 12.94 whereas the odds a woman will ever be diagnosed with lung cancer are 1 in 15.85. In addition, the 5-year relative survival rate for lung and bronchus cancer is 18.8% for women and 14% for men. The better survival rate may also apply to patients with lung cancer who have never smoked. A large study published in the Journal of the National Cancer Institute looked at more than 940,000 subjects and found a higher death rate among men who had never smoked than their female peers. And for unknown reasons, women seem to respond better to some newer chemotherapy drugs such as Erlotinib (Tarceva®) and Gefitinib (Iressa®) that inhibit tumor growth.