Lung cancer is the leading cause of cancer-related deaths in both men and women in the U.S. In women, lung cancer is the second most common cancer, with breast cancer occurring more frequently. However, more women die from lung cancer than from breast, uterine, and ovarian cancers combined.1-3
How have incidence rates changed over time?
Although the overall incidence of lung cancer has been declining, believed to be the positive result of anti-smoking strategies, the incidence of lung cancer in women is decreasing at a slower rate compared to the incidence in men.4,5 In the past, the increase of lung cancer in women can be attributed to the increase in women smoking, which had a marked increase after World War II. Trend analyses have noted that smoking has decreased more among men than in women: approximately 33.9 percent of women smoked in 1965 compared to 21 percent in 2000. In contrast, the smoking rate among men has decreased almost 50 percent since the 1950s.4,3 Some studies have suggested that women also seem to be more susceptible to the negative effects of smoking, developing cancer after fewer years of smoking compared to men.3
Women non-smokers with lung cancer
Tobacco smoking is by far the major cause of lung cancer, but smoking doesn’t account for all of the difference in the incidence rates between men and women.4,3 Among never-smokers, women have a higher incidence of lung cancer than men, but men are more likely to die from lung cancer than women. Women seem to be more susceptible to developing it but less likely to die from it. The death rate is approximately 25 percent higher in men than in women who have never smoked.6
The role of estrogen on lung cancer in women
In the search to determine why women develop lung cancer at a higher rate than men, researchers have studied the role of female sex hormones, particularly estrogen and progesterone. The exact mechanism of how these hormones may be involved in the development of lung cancer tumors is unclear, but several studies have shown a potential link between female hormones and lung cancer.3,5
One study looked at the receptor sites on cancer cells and found that lung cancer cells have estrogen receptor sites, indicating that estrogen may contribute to the cancer cells’ growth. Additional studies have demonstrated that hormone-replacement therapy, often used during perimenopause (the time period before menopause) to relieve menopausal symptoms, may increase the incidence of lung cancer and appears to increase the risk of mortality (risk of death) when used in women with lung cancer. Additionally, women who experienced menopause at an earlier age (40 years of age or younger) had a reduced risk of developing lung cancer, specifically adenocarcinoma.3,5
Differences in lung tumors and treatment in women
The type of lung cancer differs between male and female smokers. Women are more likely to develop adenocarcinoma. Squamous cell carcinoma is more common in men.3
Women generally have better responses to treatment for lung cancer, regardless of the stage of their disease, the type, or the treatment received. Studies of both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) have demonstrated that female patients have higher survival rates than their male counterparts. These improved outcomes were seen in women with lung cancer who were treated with surgery, chemotherapy, radiation, and/or targeted therapy.3