Most breast cancer patients with invasive lobular carcinoma could be treated with hormones alone and not with chemotherapy, according to a study by Virginia Piper Cancer Institute at Abbott Northwestern Hospital, part of Allina Health.
Researchers reviewed all consecutive cases of invasive lobular carcinoma breast cancer diagnosed at the Allina Health Laboratory from the past eight years. Included were 158 patients with invasive lobular carcinoma breast cancer who also had molecular testing with the Oncotype DX® gene expression test.
With Allina Health pathologists, researchers defined a model that included characteristics of a tumor most predictive of the recurrence risk identified on the Oncotype DX gene expression test: progesterone receptor expression, Ki-67 (proliferation index), estrogen receptor expression, patient age and tumor size.
"This model, if validated, may be useful in changing local practice patterns of ordering Oncotype DX testing for many ILC cases with low risk features. This would enable earlier and more cost effective treatment decision making for patients with this breast cancer subtype," said Michaela Tsai, MD, oncologist with Minnesota Oncology and breast cancer researcher at Virginia Piper Cancer Institute at Abbott Northwestern.
The Oncotype DX test costs about $4,000 and is performed by Genomic Health in Redwood City, Calif. The study, "Utility of Oncotype DX Risk Assessment in Patients with Invasive Lobular Carcinoma," was published in Clinical Breast Cancer August 19, 2015.
According to the American Cancer Society, more than 180,000 women in the United States are diagnosed with invasive breast cancer each year. About 10 percent have ILC. ILC tends to occur in women older than 60, feels like thickened tissue rather than a lump and can spread throughout the breast before it's detected.
"Less is known about the optimal management of this less common subtype of breast cancer. It has been lumped together with ductal cancer and treated the same way. Our study helps prove that not all breast cancers are the same. This subtype requires a unique treatment approach," Tsai said.