Early local therapy ineffective for de novo metastatic breast cancer

Early local therapy did not extend survival in women with de novo metastatic breast cancer and intact primary tumors, according to results from a randomized phase 3 study presented at ASCO20 Virtual Scientific Program.

Results also revealed a 2.5-fold greater risk for local disease progression without locoregional treatment, but treatment of the intact primary tumor did not appear linked to improved patient quality of life.

“For those women, local treatments for the intact primary tumor in the breast does not provide a survival advantage,” Seema A. Khan, MD, professor of surgery at Feinberg School of Medicine and Robert H. Lurie Comprehensive Cancer Center at Northwestern University, told Healio.

Khan and colleagues enrolled women with de novo stage IV metastatic breast cancer into the study between February 2011, and July 2015. They randomly assigned the 256 eligible patients to receive either optimal systemic therapy alone (n = 131) or optimal systemic therapy plus locoregional treatment (n = 125).

During follow up (average of 59 months; range, 0-91), there were 121 deaths and 43 locoregional progression events with no meaningful difference in OS.

The locoregional recurrence or progression was significantly greater in the optimal systemic therapy arm, while health-related quality of life was worse in the optimal systemic therapy plus locoregional treatment arm at 18 months after randomization. However, investigators saw no difference at 6 months (74% completion) or 30 months (56% completion).

“Women who presented with stage IV breast cancer were first treated with systemic therapy — either chemotherapy, anti-hormone medication or anti-HER2 therapy,” said Khan. “Everyone who entered the trial first got systemic therapy, and the women who had stable disease or did not, or responded, so women with stable or responding disease, were then randomized to receive local regional treatment to the breast and lymph nodes ... and they were compared to the other randomized arm, where no local regional treatment was used.”

The primary endpoints was overall survival, with locoregional disease control as a secondary endpoint. Researchers designed the trial to detect improvements in 3-year overall survival rate from 30% with optimal systemic therapy to 49.3% for optimal systemic therapy and locoregional treatment.

Early local therapy did not improve survival in patients with de novo metastatic breast cancer and an intact primary tumor, though there was a 2.5-fold higher risk for local disease progression without locoregional treatment, local regional treatment of the intact primary tumor did not lead to improved quality of life.

“The other thing we've learned from these trials is that when systemic therapy works at distance sides — if it's working in the bones and the liver and the lungs — it's also working in the breast. Most women who have effective systemic therapy will not only see improvement in their disease that other side in the body but will also see improvement in the breast. For women who don't receive surgery and radiation to the breast, it's not like they're not receiving any treatment to the breast, because whatever they're receiving systemically gets to the breast as well and has a benefit there too,” Khan told Healio.