Over the past few years, sex-based differences in lung cancer have become increasingly recognized as relevant in prognosis overall and potentially in predicting response to treatment, such as EGFR inhibitors and other targeted therapies. At ASCO 2007, a group led by Dr. Kathy Albain, long committed to learning more about sex differences in lung cancer outcomes, presented a review of results from a series of six recent chemotherapy-based trials conducted by the Southwest Oncology Group (SWOG) in the setting of advanced NSCLC, divided by patient sex (abstract here):

(Click to enlarge)

Among the 1334 patients enrolled in these six trials, 36% were women; having women under-represented on lung cancer trials is unfortunately typical (although better than it used to be in the US, and still much better than in European trials, where women constitute just 10-15% of patients in some studies). Women and men didn't differ in their characteristics going into the trial, such as age, performance status, and stage, but women were a little less likely to have weight loss of 5% of baseline weight or more compared to men (33% vs 41%).

Despite starting out with the same characteristics as the men and experiencing a very similar range and severity of treatment-related side effects as men, women had a significantly better overall survival than men, with a median survival of 11 vs. 8 months, a one year survival of 46% vs. 35%, and a two-year survival of 19% vs. 13% (P = 0.02 for the entire overall survival analysis by sex):

But it really wasn't all women. Instead, the better survival was limited to women over 60, while women and men under 60 had a very similar survival:

That may sound surprising, but we're seeing more and more that hormonal differences may be pretty important. Next I'll describe some of the mounting evidence that is converging to show that women with high serum estradiol levels (a premenopausal picture) don't do as well as women with low serum estradiol levels most commonly seen in older, post-menopausal women.