Breast ultrasounds carried out on women who found lumps in their breasts detected 100% of susppected cancers in women under 40, according to US researchers.

Researchers said that ultrasound should become the standard of care for women under 40 as the breast tumour is spotted easily and surgeries or biopsies can be expensive and dangerous procedures.

University of Washington and director of imaging at the Seattle Cancer Care Alliance Dr Constance Lehman conducted two studies testing the effectiveness of ultrasound to distinguish between potentially cancerous lumps and harmless masses in younger women, according to Reuters.

In each study the ultrasound identified cancers and benign breast changes correctly.

In November, the US Preventive Services Task Force said women should not be taught to perform self examinations in case it leads to unnecessary biopsies, expense and worry.