After DCIS, About One in Five Invasive Breast Cancers Unrelated to Original DCIS
In the years following a DCIS (ductal carcinoma in situ) diagnosis, about one in five invasive breast cancers that developed were not related to the original DCIS lesion, according to a global study.
The research was published online on June 9, 2022, by the journal Nature Genetics. Read “Genomic analysis defines clonal relationships of ductal carcinoma in situ and recurrent invasive breast cancer.”
DCIS, which starts in the milk ducts, is the most common type of non-invasive breast cancer. DCIS is non-invasive because it hasn’t spread beyond the milk ducts into other healthy tissue. About 5% to 10% of people diagnosed with DCIS develop invasive breast cancer later in life.
About the study
Researchers have long wondered whether invasive breast cancer after DCIS is:
related to the original DCIS
a new, unrelated breast cancer
If doctors can confirm whether or not DCIS leads to invasive breast cancer, they can tailor therapy and avoid overtreating many people.
In this study, the researchers did genomic analyses of original DCIS lesions as well as any invasive breast cancers that developed later to see if they shared DNA.
The study included samples of DCIS lesions from 129 women. Overall, 95 of the women were later diagnosed with invasive breast cancer and 34 of the women were later diagnosed with a second DCIS. All the recurrences — both invasive and DCIS — were in the same breast as the original DCIS.
The women were between 34 and 87 years old when they were diagnosed with the original DCIS. Half of the invasive cancers and second DCIS cases were diagnosed less than four years after the original DCIS diagnosis and half were diagnosed more than four years after the original DCIS diagnosis.
Of the original DCIS lesions:
52% were high grade
67% were estrogen receptor-positive
29% were HER2-positive
12 of the 95 women (13%) who later developed invasive breast cancer received radiation after surgery for the original DCIS
18 of the 34 women (53%) who later developed a second DCIS received radiation after surgery for the original DCIS
The researchers compared the DNA of the original DCIS lesions with the subsequent invasive breast cancers in the 95 women who were diagnosed with invasive recurrence.
The researchers found:
75% of the invasive cancers were related to the original DCIS lesions
18% of the invasive cancers were not related to the original DCIS lesions
7% of the invasive cancers had ambiguous results, meaning the researchers couldn’t tell if the cancers were related to the original DCIS
“By analyzing the largest DCIS cohort of its kind in the world, we discovered that a subset of invasive breast cancers following an initial DCIS are not related to the primary DCIS,” co-lead author Tapsi Kumar, PhD, genetics graduate student at The University of Texas MD Anderson Cancer Center, said in a statement. “[These] data challenge our prior understanding of DCIS progression and give us a starting point to identify better predictive biomarkers to determine which DCIS lesions are most likely to progress to invasive cancer.”
What this means for you
If you’ve been diagnosed with DCIS, the results of this study offer some interesting insights. Although nearly 80% of the invasive cancers that later developed after DCIS were related to the original DCIS, about 20% were unrelated.
The results question the long-standing belief that invasive breast cancer after DCIS develops from the original DCIS lesion.
The researchers pointed out that a big question coming out of the study is why some women develop two genetically different cancers in the same breast. Although the answers aren’t clear, the researchers offered a number of possibilities, including genetics and field cancerization, which means large areas of cells in tissue or in an organ have alterations that may lead to cancer.
The researchers said that future studies can build on their study’s results and work to identify the risk factors for women diagnosed with DCIS that make them likely to develop either a recurrence of DCIS or a new invasive cancer.
Learn more about Ductal Carcinoma In Situ (DCIS).
Written by: Jamie DePolo, senior editor
— Last updated on June 28, 2022, 7:55 PM