Just 9 per cent of women with DCIS had died from breast cancer 20 years after diagnosis, compared to 33 per cent who instead died from cardiovascular disease.
Researchers were looking at the outcome of 121,000 cases of DCIS detected between 1991 and 2010 in the US.
They also discovered there was almost no difference in survival rates between different treatment approaches, whether lumpectomy, radiotherapy or mastectomy.
The researchers, from Duke Cancer Institute, say that a more individualized approach needs to be adopted, and that could include watchful-waiting where treatment is delayed.
(Source: Journal of the National Cancer Institute, 2015; 107:djv262)