The apprehensive rats were more likely to have irregular reproductive cycles than adventuresome rats, and that disruption could account for hormonal differences linked to the development of cancer earlier, the scholars found. There was no difference in the length of time between onset of cancer and death in the two set of rats, however.
Because the findings have identified a difference in temperament that is associated with the onset of cancer, the findings may have implications for research on the development of cancer in humans, said Martha McClintock, the David Lee Shillinglaw Distinguished Service Professor in Psychology at the University of Chicago.
“Human studies may need to consider more basic behaviour traits than those already considered,” McClintock explained. The links between behaviour traits and cancer in rats are striking, the scholars found.
For their study, the researchers selected 81 female Sprague-Dawley rat pups. The breed is prone to development of breast and pituitary tumours. In order to minimize the differences in temperament that are accountable to differences between rat families, the researchers compared behaviour among sisters.
The rats were tested at 20 days and 11 months of age in a cage to see how willing they were to explore a new environment, which contained non-threatening items such as toys. The researchers measured adventuresomeness by recording how far the rats wandered in the environment.
They found that by age 390 days, middle age for rats, 80 percent of the fearful rats had mammary cancer while only 38 percent of the adventuresome rats had the illness. The fearful rats had a life span of 573 days, versus 850 for the adventuresome rats. They found similar life span results for females with pituitary tumours.
MEDICA.de; Source: University of Chicago