One in every five women who are told they have breast cancer doesn’t have the disease at all. Instead, they have a non-cancerous growth called a DCIS (ductal carcinoma in situ)-which is still treated with aggressive surgery or radiotherapy as if it were a cancer.
Not surprisingly, the treatment doesn’t make any difference to the likelihood of the woman dying from breast cancer, and doctors need to rethink the way they view DCIS, a new study has found.
Twenty per cent of ‘cancers’ that routine mammography detects are DCIS, which rarely develop into aggressive breast cancer. Researchers at Toronto’s Women’s College Hospital tracked the health of 108,000 women who had been diagnosed with DCIS before the age of 70, and found that 3.3 per cent had died from breast cancer up to 20 years afterwards.
Those who developed invasive cancer in the same breast were 18 times more likely to die from breast cancer than women who didn’t experience any recurrence. Lumpectomy with radiotherapy or mastectomy reduced the risk of a recurrence within 10 years, but it didn’t make any difference to whether the woman died from the cancer.
DCIS needs to be treated differently, and routine radiotherapy should be stopped, the researchers say.
(Source: JAMA Oncology, 2015; doi: 10.1001/jamaoncol.2015.2510)