The AP/Houston Chronicle on Monday examined gender differences in the development of lung cancer and three studies that are examining whether estrogen can be linked to the differences. Lung cancer this year is expected to cause the deaths of an estimated 162,000 people in the U.S., 72,000 of whom likely will be women. In addition, rates of lung cancer deaths among women are "stubbornly holding steady" in recent years, while the rates of lung cancer deaths among men have decreased, the AP/Chronicle reports. However, women on average survive longer after developing lung cancer than men, and the newest drugs to treat the disease, Tarceva and Iressa, have been more effective in women. The National Cancer Institute is funding a 720-person study -- led by Kathy Albain, a lung cancer specialist at Loyola University Health System -- to identify genes, hormones or other factors explaining the gender differences. In addition, University of Pittsburgh pharmacologist Jill Siegfried is leading a 120-person study examining whether women taking Tarceva respond better if also given the antiestrogen drug Faslodex. According to the AP/Chronicle, Siegfried's research indicates estrogen might "fuel" lung tumors as it does in many types of breast tumors. Seattle-based Cell Therapeutics also is testing the efficacy of the experimental lung cancer drug Xyotax. Previous studies find that women living with lung cancer using Xyotax had a survival rate of 45% after one year, compared with 25% among women taking standard regimens and 25% among men given either regimen, according to the AP/Chronicle (Neergaard, AP/Houston Chronicle, 5/29).