Although age has been an important risk factor of breast cancer, a study said post-menopausal women who used a hormonal intrauterine device were at 52 per cent increased risk of the disease, when compared to those who used copper a device.The findings showed the use of other hormonal contraceptives was associated with 32 per cent higher breast cancer risk among women under 50 when compared to those who did not use hormonal contraceptives.Further, women who dyed their hair also had an increased risk of 23 per cent compared to those who did not, researchers said."The biggest risk factor in breast cancer is high age, and known lifestyle-related risk factors include late age at first birth, small number of children, high alcohol consumption and sedentary lifestyle," Sanna Heikkinen from the University of Helsinki in Finland, said in her dissertation.In addition, women who undergo opportunistic mammography screening -- the process of using low-energy X-rays to examine the human breast -- were also found to be at risk of developing breast cancer.In the study, more than 60 per cent of participants reported having had a mammography screening before the age of 50."Women should be more extensively informed of the harms of opportunistic mammography, such as accumulating radiation burden and the potential consequences of false positive or negative findings," Heikkinen said.For the study, the team analysed self-reported survey data from 8,000 breast cancer patients and 20,000 controls from Finland.