Non-Invasive Breast Cancer Survivors Face Much Higher Risk of Developing Invasive Disease

Ductal carcinoma in situ (DCIS), cancer confined to the milk ducts, is considered non-invasive breast cancer. Once it spreads beyond that, it’s considered invasive. Treatment for DCIS tends to be less extensive, either a lumpectomy or mastectomy, possibly followed up with hormone therapy. Though it is treatable and a very early form of the disease, what are the odds that a patient will go on to develop invasive breast cancer after this diagnosis? Apparently quite high.

Research recently published in The BMJ investigated invasive cancer rates in women who had initially been diagnosed with DCIS outside the UK’s NHS screening program. The screening program is provided to women between the ages of 50 and 70, so cases discovered outside of the program may be in women outside this age range, who didn’t respond to a screening invitation, or who were diagnosed between screenings.

The research focused on all 27,543 women in England who were diagnosed with DCIS outside the screening program between 1990 and 2018, with their health records examined at the end of 2018. By that time, 3,651 of these patients had gone on to develop invasive breast cancer. Researchers say that was more than four times the national rate in the general population.

The odds were higher the younger a patient was when diagnosed with DCIS. For patients who had been diagnosed before age 45, there was a 27.3% risk of developing invasive breast cancer over 25 years, and for those who had been diagnosed between 45 and 49, the risk was 25.2%. It then fell to 21.7% for those in their 50s and 20.8% for those in the 60 to 70 age range. Overall, there was a lower risk for women who had undergone mastectomies versus lumpectomies, as well.

When it came to mortality, 908 women in the study died of breast cancer, which was also nearly four times the rate of the general population. Again, those who were diagnosed before 45 had worse outcomes. There wasn’t a difference found in mortality rates between patients who had undergone mastectomy versus lumpectomy.

The team also found that women who were diagnosed with DCIS outside the screening program had worse outcomes than those who were diagnosed as part of it.

Currently, the NHS calls for DCIS survivors to get yearly mammograms for five years after treatment, and then they go back to every three years after that. The researchers say the findings suggest that may need to be reconsidered.

Gurdeep Mannu, lead author and Clinical Research Fellow in Cancer Surgery at Oxford Population Health, says, “This is the first time that we have been able to evaluate the long-term outcomes in all women diagnosed with DCIS on a population level in England. We have provided evidence that the increased risk of invasive disease and breast cancer death following a diagnosis of DCIS in both screen detected and non-screen detected DCIS lasts for at least 25 years. These findings should inform considerations regarding the frequency and duration of surveillance following a diagnosis of DCIS, particularly for women diagnosed at younger ages.”

If you’d like to read more of the study, click here.