Study finds stress worsens ovarian cancer

WASHINGTON (Reuters) – Stress causes ovarian cancer tumors
to grow and spread more quickly in mice, U.S. researchers
reported on Monday in a study that provides one of the first
biological links between stress and cancer.

In the mice, stress hormones attach directly to tumor cells
and stimulate new blood vessel growth and other factors that
lead to faster and more aggressive tumors, the researchers
said.

The study published in the journal Nature Medicine also
found that a blood pressure drug reverses the effect.

Studies aimed at finding out if stress causes cancer have
not come up with a clear answer — and some have clearly ruled
out any link between stressful life events, such as divorce or
job loss, and later cancer.

But many people believe stress can cause cancer.

Dr. Anil Sood of The University of Texas M.D. Anderson
Cancer Center and colleagues noticed that ovarian cancer
patients who reported high levels of stress in their lives also
had higher levels of a protein called VEGF, which stimulates
blood vessel growth in tumors.

The patients who had more social support in their lives had
lower levels of VEGF.

So the team infected mice with ovarian cancer and then
stressed some by confining alone them in a small space for two
or six hours. Mice stressed for six hours had 3.6 times as many
tumors.

And in half the stressed mice the tumors had already spread
to the liver or spleen.

To their surprise, Sood’s team found that the tumor cells
have receptors, molecular doorways, that are configured for
stress hormones.

When activated, they start a process known as angiogenesis
– making the little blood vessels that tumors need to nourish
themselves. Not only was VEGF activated, but so were two other
compounds involved in sustaining tumors called MMP2 and MMP9.

“This study provides a new understanding of how chronic
stress and stress factors drive tumor growth,” Sood said in a
statement.

So then the researchers gave the mice a beta-blocker heart
drug called propranolol, which lowers blood pressure using
these same stress receptors, called beta adrenergic receptors.

“The concept of stress hormone receptors directly driving
cancer growth is very new,” Sood said.

“Not much had been known about how often these receptors
are expressed in cancer, and more importantly, whether they had
any functional significance. Our research opens a new area of
investigation.”