Researchers have developed a test that predicts the likelihood that a person with invasive lobular breast cancer (ILC) will benefit from chemotherapy. The findings were published in the June 27, 2019 issue of Nature Partner Journals Breast Cancer, a joint publication between Nature and the Breast Cancer Research Foundation.
“In this study, we pulled together a set of 194 genes that, when working together, act as a signature to help clarify which patients are likely to have a positive outcome with their breast cancer,” said lead author of the study Amy McCart Reed, Ph.D., lead author and postdoctoral fellow at the University of Queensland Centre for Clinical Research, in a press release. The authors of the study call these 194 genes a ‘meta gene.’
“In this study, we have derived the first meta-gene signature focused on prognostication in ILC,” they wrote.
Invasive lobular breast cancer account for about 10% of the 245,000 cases of breast cancer diagnosed in the U.S. every year, according to the Centers for Disease Control and Prevention. It begins in themilk-producing glands (lobules) of the breast. It is considered invasive when the cancer cells have broken out of the glands, giving them the potential to spread to the lymph nodes and other areas of the body.
Although this type of cancer makes up a small percentage of the total cases, it is more likely to spread than the more common type, invasive ductal carcinoma, which accounts for 80 percent of the diagnosed cases. Women with the lobular kind are often diagnosed with large tumors that are difficult to remove surgically because these kinds of tumor are harder to identify via mammography and often need mastectomies. The study’s authors describe invasive lobular breast cancer as having“an inherently invasive growth pattern” and can “highly metastatic.” Many don’t do well on chemotherapy, but do respond well to endocrine therapy.
The goal of the new test is to save these women from the rigors of chemotherapy. It is particularly important because the diagnostic tests available now were developed using ductal carcinoma tumors.
In the current study, McCart Reed and her colleagues describe their new polygenic risk test, which they call LobSig, as an important tool for precision oncology, allowing physicians match treatments for invasive lobular breast cancer to patients based on omics data.
“If they have a low-risk signature score, it means we might relieve them of the burden of chemotherapy. If they have a high-risk signature score, we could continue to recommend chemotherapy as the course of treatment,” McCart Reed said.
In developing Lob Sig, the researchers used omics data for about 300 patients for which 10 years of follow-up data were also available. Mathematical analysis of these data identified the 194 informative genes that make up LobSig. Using the signature, the researchers were able to predict outcome status status predicted outcome with nearly 95 percent. Together with pathology information, the test could provide a robust way to accurately predict the course of ILC in each patient. “This signature warrants further analysis and development, and validation on expanded retrospective cohorts of ILC with detailed treatment information,” the researchers wrote.