Women diagnosed with ductal carcinoma in situ during breast screening face an increased risk of developing breast cancer later in life, a study published today says.
The risks were more than double those of the general population, even for women diagnosed with low or intermediate grade DCIS, and lasted for at least 20 years after diagnosis, say the researchers writing in the new edition of The BMJ.
Although DCIS is not immediately life-threatening and has a good prognosis, it can increase the risk of developing an invasive breast cancer later on, although the extent of this extra risk is uncertain.
Researchers at the Nuffield Department of Population Health in the University of Oxford and Public Health England examined data from 35,024 women in England who were diagnosed with DCIS by the NHS Breast Screening Programme from 1988 until March 2014.
They compared rates of invasive breast cancer and of death from breast cancer with the corresponding national rates for women of the same age in the same calendar year.
They found that by December 2014, 2,076 women had developed invasive breast cancer, an incidence rate of 8.82 per 1,000 per year and more than double the number expected from national rates.
In the same group of women, 310 died from breast cancer, a death rate of 1.26 per 1,000 per year and 70% more than expected from national rates.
For both invasive breast cancer and death from breast cancer, the increases continued for at least two decades.
The results also suggest that women who had more intensive treatment, had a lower long-term risk of invasive breast cancer than those who had breast conserving surgery, even when radiotherapy was given.
Surveillance of women after a DCIS diagnosis focuses just on the first few years, with most women in the UK being recalled for yearly surveillance mammograms for five years, after which further follow-up is every three years via the national screening programme up to age 70 years.
“We have, however, provided evidence of the long term nature of the risk of invasive disease after a diagnosis of DCIS, even for women with low or intermediate grade disease,” they write.
Mannu GS, Wang Z, Broggio J et al. Invasive breast cancer and breast cancer mortality after ductal carcinoma in situ in women attending for breast screening in England, 1988-2014. BMJ 28 May 2020
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