Breast cancer surgery could trigger tumor growth, relapse

Breast cancer surgery may actually inflate a patient’s chances of metastasis and relapse, researchers reported in Science Translational Medicine this week—and the healing process might be partially responsible.

Early metastatic recurrence isn’t a rarity in breast cancer patients, first author Jordan A. Krall, PhD, and colleagues wrote. In fact, it’s pretty common.

“Patients undergoing surgical resection of primary breast tumors confront a risk for metastatic recurrence that peaks sharply 12 to 18 months after surgery,” the authors said. “The cause of early metastatic relapse in breast cancer has been long debated, with many ascribing these relapses to the natural progression of the disease.”

Other clinicians hypothesize that some aspect of surgical tumor resection itself triggers outgrowth of metastases that were otherwise dormant, Krall et al. wrote. Some attribute the anomaly to tumor cells that are released into circulation during surgery.

With such little evidence, the authors said clinical research is unable to distinguish between hypotheses.  

“Such uncertainty hinders the development and application of therapeutic approaches that could potentially reduce early metastatic relapse,” they said. 

Krall and co-authors were able to definitively link breast cancer surgery and its subsequent healing process with the outgrowth of tumor cells in rodent models. Using a common wound-healing model in mice carrying breast cancer cells and avoiding surgery, the team found the mice’s T cells were able to keep distant tumors in check, but inflammation induced by wound healing disrupted that “delicate balance.”

Perioperative anti-inflammatory treatment, however, seemed to reduce early metastatic recurrence in the mice—and the researchers said that’s what they’d expect in humans, too.

Radiologist Jason R. Williams, MD, of the Williams Cancer Institute in Alabama, said Krall et al.’s findings pave the way for less invasive breast cancer treatments, like ultrasound-guided percutaneous cryoablation.

“Certainly, it just makes sense that if the healing response may enhance cancer growth, then a less invasive procedure such as cryoablation theoretically should reduce that risk, though I do think we need further studies to refine these treatments,” Williams said in a news release. “Also, this is likely not just unique to breast cancer. It is probably the same in other cancers, as well.”