A study has revealed that women may be undergoing distressful cancer treatment needlessly because as many as one in three cases of breast cancer detected by screening proves to be harmless.

Data from Britain, Canada, Australia, Sweden and Norway suggests that a significant proportion of women have breast cancer “overdiagnosed” when the disease is unlikely to kill them or spread to other parts of the body.

The Times reports that many women have breast cancer diagnosed even though they have benign tumours. These woman may even undergo unnecessary surgery, radiotherapy or chemotherapy as a result.

However, it is important that this data does not put off woman from having a screening as breast cancer still kills 12,000 women a year. It is estimated that screening saves 1,400 lives every year in England alone.