It is seen that brain tumours are more common in men and more harmful than similar tumours in females. A research published in the Journal of Clinical Investigation, sought to look into the reasons for this and found that there was one particular protein called Retinoblastoma Protein (RB) that is less in male brain cells when compared to female brain cells. RB reduces the risk of cancer and extremely essential. The study was conducted by Washington University School of Medicine in St. Louis.
Senior author and associate professor of pediatrics, neurology and anatomy and neurobiology, Joshua Rubin, MD, PhD said that this was the first time someone attempted to identify sex-linked difference that affects tumour risk and "is intrinsic to cells, and that's very exciting." The results he said suggested that an analysis into the multiple pathways linked to cancer was required, checking for sex differences. "Sex-based distinctions at the level of the cell may not only influence cancer risk but also the effectiveness of treatments," he stated.
Rubin explained that in clinical trials data from patients of both genders were examined together and this could be masking positive or negative responses that are limited to one sex. "At the very least, we should think about analysing data for males and females separately in clinical trials."
Due to the differences between the sex hormones which cause biological differences in males and females, there is a difference in the rates of sex linked diseases between the two. They are seen to cause different symptoms in men and women.
But they stated that sex hormones could not account for the differences in brain tumour risk. Rubin said, "If the sex hormones were causing this effect, we'd see major changes in the relative rates of brain tumours in males and females at puberty. But they don't happen then or later in life when menopause changes female sex hormone production."
With the help of a cell model of glioblastoma, Rubin proved that it is much easier for male cells to become tumours. The found that male brain cells turned cancerous faster after a succession of genetic alterations and it was more than female brain cells. The researchers studied three genes, neurofibromin, p53 and RB which suppress cell division and cell survival. In many cancers they are mutated and disabled. The experiment revealed that RB was inactive in male brain cells when compared to females. It was also seen that when this protein was disabled in female brain cells they turned cancerous too.
"There are other types of tumours that occur at different rates based on sex, such as some liver cancers, which occur more often in males," Rubin said. "Knowing more about why cancer rates differ between males and females will help us understand basic mechanisms in cancer, seek more effective therapies and perform more informative clinical trials."