The researchers explained that in mice, the stress hormones directly attach themselves to the tumor cells and act by stimulating new blood vessel growth and other factors that leads to faster and more aggressive tumors. The study that has been published in the journal Nature Medicine also found that a blood pressure drug reverses the effect.
They explained that their studies that had been conducted with an aim of trying to find as to whether stress does causes cancer have not come up with a clear answer while certain studies have clearly ruled out any link between stressful life events, such as divorce or loss of job or probably even cancer.
Dr Anil Sood MD Anderson Cancer Center of the University of Texas and colleagues had noticed that ovarian cancer patients who were reporting high levels of stress in their lives also had higher levels of a protein called VEGF, which stimulates blood vessel growth in tumors. While, they noted that those patients who had more social support in their lives had lower levels of VEGF.
Based on these findings the team then infected the study mice with ovarian cancer and then induced stress on some by confining alone them in a small space for two or six hours. They found that the mice that had been stressed for 6hours had 3.6 times as many tumors, and that in half of those mice, the tumors had already spread to the liver or spleen.
Sood's team also reported that they were surprised to note that the tumor cells have receptors, or molecular doorways, that are configured for stress hormones. They further found that when activated, they start a process that is known as angiogenesis, which makes the tiny blood vessels that tumors need to nourish themselves. They found that not only had VEGF activated, but also were two other compounds called MMP2 and MMP9, which were involved in sustaining tumors.
Dr Sood said, "This study provides a new understanding of how chronic stress and stress factors drive tumor growth." He further added, "The concept of stress hormone receptors directly driving cancer growth is very new."