Can Local Therapy Extend Life in Metastatic Breast Cancer?

By: Frederik Joelving

From: medscape.com

Women with de novo metastatic breast cancer that is confined to a single distant organ may live longer when they undergo resection of the primary tumor, a large cohort study suggested.

The study, of over 22,000 US women with the diagnosis, found that while local therapies were uncommon, they were associated with longer overall survival: Patients who underwent resection of the primary breast cancer, with or without metastatic-site ablative therapy, survived longer than those who received no local therapy.

Metastatic site ablation on its own, however, showed no survival benefit, according to findings published in JAMA Surgery.

The work “highlights how the story is not over for primary site surgery in the setting of metastatic breast cancer,” said Rita Mukhtar, MD, breast surgeon at the University of California, San Francisco, who was not involved in the study.

About 6% of new breast cancer cases in the US are de novo metastatic breast cancer. Systemic therapies are standard, but some retrospective studies have suggested better survival when women also undergo resection of the primary tumor. Prospective studies, however, have been disappointing.

Many argue that resection of the primary tumor shouldn’t be done unless the goal is local control or palliation of symptoms, Mukhtar told Medscape Medical News.

However, she said, the authors of the new study “have done a lot of work showing that not all patients with stage IV are the same.”

For the study, Jennifer Plichta, MD, of Duke University Medical Center in Durham, North Carolina, and her colleagues identified 22,433 patients in the National Cancer Database who had been diagnosed with de novo metastatic breast cancer confined to a single distant organ (brain, bone, liver, or lung). The median age in the cohort was 61 years, and more than two thirds had bone-only metastases.

All patients received at least one type of systemic therapy. Most (68%) received no local therapy, while roughly 15% underwent surgical resection of the primary tumor, 11% received metastatic-site ablative therapy (surgery or radiation), and 6% received both local therapies.

However, she said, the authors of the new study “have done a lot of work showing that not all patients with stage IV are the same.”

For the study, Jennifer Plichta, MD, of Duke University Medical Center in Durham, North Carolina, and her colleagues identified 22,433 patients in the National Cancer Database who had been diagnosed with de novo metastatic breast cancer confined to a single distant organ (brain, bone, liver, or lung). The median age in the cohort was 61 years, and more than two thirds had bone-only metastases.

All patients received at least one type of systemic therapy. Most (68%) received no local therapy, while roughly 15% underwent surgical resection of the primary tumor, 11% received metastatic-site ablative therapy (surgery or radiation), and 6% received both local therapies.

According to the researchers, the findings are consistent with the hypothesis that primary tumor resection may help slow disease progression, whereas targeting metastatic lesions alone may not be enough. Alternatively, they noted, some patients may have received certain treatments with palliative intent only.

“The main takeaway is that we clearly need more research on local therapies for patients with de novo metastatic breast cancer,” Plichta told Medscape Medical News.

She said that prior trials of local therapy in this patient population have not put enough focus on identifying those most likely to benefit.

“There are currently some prospective studies in the works that will hopefully start to address this question in a more rigorous way,” Plichta said, adding that the current findings support such efforts.

An editorial published with the study was cautiously optimistic.

“While its large cohort design provides valuable insights, the retrospective nature and inherent selection bias — where younger, healthier patients with favorable tumor biology are most likely to receive surgery or ablation — limit causal inference,” wrote Leah Kim, MD, of Yale New Haven Hospital in New Haven, Connecticut, and colleagues.