DCIS Diagnosed Outside Regular Screening Increases Invasive Disease Risk by 400%
Women diagnosed with DCIS that was found before regular breast cancer screening started or in between regular mammograms have a more than four times higher risk of invasive disease and this risk lasts for at least 25 years, according to a British study.
The research was published online on Jan. 24, 2024, by The BMJ.
Why do the study?
Research shows that if DCIS is found during regular screening, the risk of invasive breast cancer is more than doubled and this increase in risk lasts for at least 20 years.
But little information was available on invasive breast cancer risk and DCIS that was found before a woman was old enough to start regular mammograms or in the time in between regular mammograms.
So the researchers did this study to help fill in the knowledge gaps.
About the study
The National Health Service (NHS) oversees the breast cancer screening program in England. Starting at age 50, anyone who identifies as female and is registered with a general practitioner is sent a letter every three years inviting them to have a screening mammogram. Women stop getting the letters after age 70.
The researchers looked at the records of women diagnosed with DCIS between 1990 and 2018. Women were excluded from the study for a variety of reasons, including if they had a history of invasive cancer (other than non-melanoma skin cancer), less than six months of follow-up, or were diagnosed with invasive cancer within six months of DCIS diagnosis, among other things.
The researchers then separated the records into women with DCIS detected during a regular screening mammogram and women with DCIS detected outside regular screening mammograms.
Of the 27,543 women with DCIS found outside regular screening, 22,753 were diagnosed with DCIS in one breast and had treatment:
19.5% had lumpectomy and radiation
36.7% had lumpectomy alone
43.8% had mastectomy
The other 4,790 women, including 4,582 who were diagnosed with DCIS in one breast, had no treatment.
By the end of the study, 3,651 women with DCIS detected outside regular screening had been diagnosed with invasive breast cancer:
1,950 cancers were in the same breast as the DCIS
1,103 cancers were in the opposite breast
it wasn’t known if 598 of the cancers were in the same or opposite breast
Overall, the rate of invasive breast cancer diagnosed in women with DCIS detected outside regular screening was more than four times higher than the average rate. This increase in risk lasted for at least 25 years.
The youngest women diagnosed with DCIS outside regular screening had the highest increase in risk:
Women diagnosed with DCIS when younger than 45 were 7.33 times more likely than average to be diagnosed with invasive disease.
Women diagnosed with DCIS between the ages 45 and 49 were 4.28 times more likely than average to be diagnosed with invasive disease.
Women diagnosed with DCIS between the ages of 50 and 59 were 3.37 times more likely than average to be diagnosed with invasive disease.
Women diagnosed with DCIS between the ages of 60 and 70 were 3.49 times more likely than average to be diagnosed with invasive disease.
Women diagnosed with DCIS at age 71 or older were 4.58 times more likely than average to be diagnosed with invasive disease.
If women diagnosed with DCIS that was found outside regular screening were diagnosed with invasive breast cancer, they were more than four times more likely to die from breast cancer than the average woman diagnosed with breast cancer.
What this means for you
It’s important to remember that breast cancer screening recommendations are different in England than they are in the United States. In England, after a DCIS diagnosis, a woman has a mammogram once a year for the next five years. After those five years, women who are ages 50 to 70 are part of the NHS screening program and receive a mammogram invitation once every three years. Women younger than 50 with a history of DCIS don’t receive regular mammograms more than five years after the DCIS diagnosis. This gap could be part of the reason why the risk of invasive breast cancer was so much higher in younger women diagnosed with DCIS outside regular screening.
In the United States, a woman with a history of DCIS is considered to have a much higher risk of invasive disease. So it’s likely she would have screening every six months, alternating between mammograms and breast MRI or ultrasound.
Despite the differences between breast cancer screening in England and the United States, the results of this study are concerning. The most important take-away is knowing your personal risk of breast cancer. The American College of Radiology recommends that all women, but especially Black women and women of Ashkenazi Jewish descent, be evaluated by a doctor to find out if they’re at higher-than-average risk for breast cancer no later than age 25. You can ask your primary care doctor or gynecologist to do an assessment of your breast cancer risk or have a doctor refer you to a breast clinic for evaluation.
Updated on April 27, 2024