Under-representation of women in high-impact published clinical cancer research.

Background: Adequate representation of women in research has been deemed essential.

Methods: Cancer research published in 8 journals in 2006 was reviewed. The percentage of women among study participants was compared with the proportion expected from population-based estimates of sex-specific cancer incidence, using binomial tests. Differences were assessed in sex distribution of participants by funding source, author sex, and focus of research with the Student t test, and in a linear regression model controlling for cancer type.

Results: A total of 1534 cancer research articles were identified, of which 661 (representing 1,096,098 participants) were prospective clinical studies and were analyzed further. For all 7 non-sex-specific cancer types assessed, the majority of studies analyzed included a lower proportion of women than the proportion of women among patients having cancer of that type in the general population. Among studies focusing on cancer treatment, women constituted a significantly lower overall proportion of the participants in the analyzed studies than expected for 6 of 7 non-sex-specific cancer types (P < .001). Among non-sex-specific studies, the mean percentage of participants who were women was 38.8%. Non-sex-specific studies reporting government funding had a higher percentage of female participants (mean 41.3% vs 36.9%; P = .005). In a regression model controlling for cancer type, lack of government funding (P = .03) and focus on cancer treatment (P = .03) were found to be independent significant predictors of a lower percentage of female participants.

Conclusions: Women were under-represented as participants in recently published, high-impact studies of non-sex-specific cancers. Studies that received government funding included a higher proportion of female subjects.