Psychosocial stressors and mammary tumor growth: an animal model

Stressful life events and the ability to cope with stress may play a role i n the progression of breast cancer; however, the complex relationship betwe en stressors and tumor growth is difficult to investigate in humans. Our st udies have utilized the androgen-responsive Shionogi mouse mammary carcinom a (AR SC115) in male mice to investigate the effects of social housing cond ition on tumor growth rates and responses to chemotherapy. We demonstrate t hat, depending on social housing condition, mammary tumor growth and respon se to chemotherapy can both increase and decrease. We have examined the pos sible role(s) of 1) psychosocial variables, 2) testosterone and corticoster one, hormones altered by stress and known to stimulate SC115 cells in vivo and in vitro, 3) NK cells, one of the body's first lines of defense against tumor cells, 4) stress proteins, in mediating the differential tumor growt h rates observed in our model. This review discusses the investigations we have undertaken to elucidate the mechanisms through which a psychosocial st ressor, social housing condition, can alter tumor growth rate. (C) 1999 Els evier Science Inc. All rights reserved.