Most women who are diagnosed with breast cancer go on to develop symptoms of post-traumatic stress disorder (PTSD), a new study has found.

PTSD is an anxiety disorder that can occur after experiencing an intensely stressful event in which grave physical harm occurred or was threatened. It has been well documented in relation to military conflict, but it can also occur as a result of other scenarios, such as road traffic accidents, a violent assault or a serious illness.

Common symptoms include sudden outbursts of anger, feelings of detachment, emotional numbness and nightmares. 

German researchers studied 166 women who had been newly diagnosed with breast cancer. Over the next year, the women were assessed for PTSD at three specific points in time. These results were compared with a control group of women who had not been diagnosed with cancer.

The study found that between the time of the diagnosis and the beginning of treatment, 82% of the participants were found to be displaying symptoms of PTSD.

While just 2% of the participants were still diagnosed with the disorder one year after discovering they had breast cancer, almost 60% continued to display one or more symptoms at this point.

"That the high level of stress should persist for such a long time is particularly striking," commented lead researcher, Dr Kerstin Hermelink, of Ludwig-Maximilians-Universitaet in Munich.

She also noted that where participants had previously experienced a traumatic event, such as a violent assault or serious accident, 40% said that having breast cancer was more traumatic.

"Doctors should be made aware of the fact that the majority of breast cancer patients develop symptoms of post-traumatic stress subsequent to diagnosis, and need to receive the appropriate support," Dr Hermelink added.

Details of these findings are published in the journal, Psycho-Oncology.