By Sara Nick
Many breast cancer patients develop recurrence years after the original diagnosis, despite following a long-term medication protocol after initial treatment.
Mayo Clinic scientists are taking a closer look at which factors contribute to risk of recurrence, including the subtype of cancer patients have.
“Understanding which patients are still at risk of late recurrence will help ensure that particular patients are getting the long-term treatment that matches their needs,” says E. Aubrey Thompson, Ph.D., a researcher at Mayo Clinic in Florida who specializes in breast cancer genomics. “However, not all patients will need prolonged treatment.”
Dr. Thompson is the senior author of a new study published in the Journal of Clinical Oncology. For this work, his team looked at up to ten years of follow-up data for thousands of patients to assess the risk of breast cancer recurrence after initial cancer treatment.
The researchers were particularly interested in a breast cancer subtype that is HER2-positive and hormone-receptor positive. HER2-positive cells produce too much of a protein that promotes the growth of cancer. When a cancer is also hormone-receptor positive, hormones fuel the growth of its cells. The HER2-positive subtype, which can be aggressive, accounts for about 25% of female breast cancer cases.
"The risks of late recurrence in HER2-positive breast cancer have been understudied," the paper's first author, breast oncologist Saranya Chumsri, M.D., explains. Additionally, while there are multiple effective treatments that target the protein involved in HER-positive cancer, scientists do not know how well these treatments can prevent recurrence long term.
In this research, the investigators found a low risk of long-term cancer recurrence in patients with this subtype who received trastuzumab-based chemotherapy after surgery, with 3% incidence of recurrence between years 5-10 in patients with no lymph node involvement.
Further, their data suggests a long-term benefit of trastuzumab among patients with this subtype.
“It’s often recommended that hormone-receptor-positive breast cancer patients take medication for many years to prevent breast cancer recurrence,” Dr. Chumsri says. “However, not every patient may need this prolonged therapy. When it comes to preventing late relapse in this group of patients, our data suggest that the benefit of trastuzumab persisted long term and this group of patients may have lower risk of late recurrence. If so, this group of patients may be able to avoid the long-term side effects of endocrine therapy.”
“This research adds to our overall knowledge of risk of late recurrence in different subtypes of breast cancer,” she adds.
More work is needed to confirm these findings, but the investigators hope their data will contribute to the development of new models that may better define the risk of late relapse for breast cancer patients. This would help doctors make informed decisions about the long-term use of endocrine therapy to prevent recurrence of this disease.
This study was supported by the National Institutes of Health, with additional funding from the Breast Cancer Research Foundation, Bankhead-Coley Research Program, DONNA Foundation, and Genentech.