The scientists at the University of Pittsburgh Cancer Institute say invasive lobular cancer which forms in the milk producing glands has a unique growth pattern that fails to form a lump.
Researchers say its genetic markers indicate patients may benefit from drug therapies other than those typically prescribed for the more common cancer, which forms in the breast ducts.
Patients with invasive lobular carcinoma are typically treated through surgical removal of the cancer, followed by chemotherapy or hormone therapy or both, usually with the estrogen-mimicking drug tamoxifen or estrogen-lowering aromatase inhibitors, the same as patients with invasive ductal carcinoma.
“However, recent analyses have shown that a subset of patients with lobular carcinoma receive less benefit from adjuvant tamoxifen than patients with ductal carcinoma,” said senior author Steffi Oesterreich, Ph.D., professor at UPCI.
Dr. Oesterreich continued, "“our study, the largest of its kind, indicates an issue with the estrogen receptors inside lobular carcinoma cells and points to a potential target for drug therapy in future clinical trials, which we are developing.”
Lobular carcinomas account for 10 to 15 percent of breast cancers, while ductal carcinomas make up nearly 80 percent, according to the study.