(This is something I wrote from a presentation about metastatic breast cancer given at the San Antonio Breast Cancer Symposium that was held in December.
I used some of these procedures, even though there's little evidence that they work. The current clinical trial at U Chicago that involves some of the procedures referred to in this story can be found at clinicaltrials.gov/ct2/show...
The study compares MBC patients who receive only the standard of care and those that receive the standard of care + a local procedure. It is currently recruiting.)
Combining systemic and local therapies to treat MBC
In the quest to use as many options as possible to treat MBC, oncologists sometimes consider a multidisciplinary approach to treat patients who have oligometastatic disease, or otherwise a small number of tumors in either one or a few organs. Up to 50% of newly diagnosed metastases among women who go on clinical trials are oligometastases, and about 6% of new breast cancers in the United States are diagnosed as stage IV, known as de novo, much of which is limited in metastatic spread, Dr. Seema Khan said. She presented the discussion of combining system and local therapies and is professor of surgery at Lynn Sage Breast Center, Northwestern University.
The approach adds local procedures such as radiation, surgery and interventional radiology (IR) to systemic therapy. IR procedures include radiofrequency ablation (burning the tumor with radiofrequency waves), microwave ablation, cryoablation (freezing the tumor) and nanoelectroporation (using electrical capacity).
Despite the lack of compelling proof from randomized clinical trials and information about the biology and biomarkers that underlie oligometastasis, oncologists seem to be rapidly adopting multidisciplinary approaches, according to Dr. Kahn.
The question is whether oligometastatic patients should be considered for multidisciplinary treatment, rather than clinical trials.
Thus far, evidence of efficacy includes a prospective analysis of 121 patients who received stereotactic body radiotherapy (SBRT), which is radiation aimed very specifically at a tumor. The results showed that of the 39 patients who had MBC the overall survival (OS) was 46% at 6 years. Most of the MBC patients had 1 or 2 lesions. A prospective study looks to recruit patients to a clinical trial to disprove a particular hypothesis.
Several retrospective studies of liver resection surgery for MBC showed 5-year median survival rates between 27% and 48%. Poor survival was associated with a disease-free interval of less than 4 years, hormone receptor negative status, poor response to chemotherapy, and positive resection margins. A retrospective analysis looks at data from different studies that were already conducted. Although researchers avoid the expense of conducting a prospective clinical trial because the data are ready-made, they can face drawbacks when different studies did not use the same criteria. For example, one study may define oligometastasis as three or fewer lesions, while another study may expand that the definition to five or fewer.
Currently, researchers are enrolling MBC patients for a phase IIR/III trial of standard systemic therapy with or without SBRT and/or surgical resection of all metastases. Stratification will include number of metastases (1 vs. > 1), hormone receptor status, HER2 status, and whether the patient had received first-line chemotherapy. If ablative therapy improves OS when added to standard systemic treatment, then the protocol will shift further to multidisciplinary treatment, Dr. Kahn said. If not, then the use of off-label SBRT should cease, she said.