Gender and ploidy in cancer survival

Females carry a better prognosis than men for many cancer types. We hypothesized that chromosomal changes, in particular numerical alterations of the sex chromosomes or the presence of near-triploidy may contribute to these gender differences.

To characterize the influence of gender a literature search was performed for survival data of 27 tumor types. All entities were categorized by the strength of evidence for differences in survival between females and males. To test our hypothesis the Mitelman database of chromosomal alterations was evaluated for the major tumor types occurring in both women and men. Numerical gonosome alterations were documented and mean chromosome numbers were converted into histograms to provide insight into the ploidy level of 37 cancer types.

In general, a survival advantage of women could be shown for most, but not all cancer types. In addition, 36.859 karyograms were analyzed. Numerical gonosome alterations were more frequent in males than females indicating a potential link with gender differences in survival. Neartriploidy was a common phenomenon in many cancer types suggesting that it represents a metastable condition of the cancer genome. It was not related to gender differences in survival. However, the extent of triploidy and aneuploidy was associated with poor prognosis in carcinomas. There was no single case in the Mitelman database with normal chromosome number (n = 46) that did not carry at least one structural or numerical aberration.

Our study highlights the importance of chromosomal changes in tumor formation and progression. In addition, it suggests potential associations with gender specific differences in survival.