De Novo Metastatic Breast Cancer: Does Local Therapy Help?

De novo metastatic breast cancer is breast cancer that is already metastatic or Stage IV at the time of diagnosis. Unfortunately, over the years, I have known a number of patients for whom this was true. Some had been ignoring symptoms or obvious signs of trouble. I have known a few women who, at the time they first came for medical attention, had a large tumor that was distorting the breast.

As simplistic as it sounds, cancer that remains in the breast is not lethal; the danger is in breast cancer cells that have invaded vital organs.

Usually, a de novo metastatic breast cancer diagnosis is made because of persistent pain, neurological concerns, or a long period of malaise that could not be explained. More often, this diagnosis is made during the staging and work up of a new patient who is initially thought to have earlier stage breast cancer. If there are particular concerns about the possible extent of someone's cancer, the patient will likely undergo scans or MRIs prior to surgery. Occasionally, these tests find that the cancer has already spread beyond the breast, and the cancer is Stage IV rather than an earlier stage that was expected.

Metastatic breast cancer is treatable, but not curable. It is often considered a chronic disease and many people have active lives while living with this diagnosis. It is estimated that approximately 6% of all breast cancers in the United States are de nova metastatic. The usual standard of care is systemic therapy, meaning chemotherapy or targeted therapy, that can attack cancer cells anywhere in the body.

It is often confusing and distressing to leave the breast tumor alone since the usual instinct is to want it removed ASAP. The explanation has been something along the lines of shutting the barn door after the horse has escaped and the need to focus on cancer cells that may be much more life-threatening than those in the breast.

Breast surgery or radiation to the breast focuses only on the primary tumor and does nothing to treat cancer cells that are circulating elsewhere. The role of systemic therapy has always been to go after those distant cells and, ideally, to prevent their lodging elsewhere in the body. If a person already has metastatic cancer, the goal is to reduce or eliminate the cells that are outside of the breast. As simplistic as it sounds, cancer that remains in the breast is not lethal; the danger is in breast cancer cells that have invaded vital organs.

Over the years, some doctors and researchers have questioned this approach. They wondered whether it also made sense to remove the primary breast tumor. One common sense view is that it could be a way to greatly reduce the total number of breast cancer cells in the body, the so-called tumor burden.

Some retrospective studies that looked back on data already collected suggested that including surgery to remove the primary breast tumor could extend life. Certainly, I have known a number of patients who pushed hard for this surgery, as they were unable to feel comfortable with the known breast tumor still in place.

At this year's virtual ASCO meeting, results from Trial E2108, a national randomized trial, answered the question. This study enrolled almost 400 women who had been diagnosed with de novo metastatic breast cancer. All began treatment with systemic therapy. After 4 to 8 months of treatment, those women whose cancers had not grown were randomly assigned to continue on with chemotherapy or to take a break to have breast surgery before continuing the treatment. In addition to answering whether having local treatment to the breast would result in living longer, the questions also included assessments of quality of life (QOL).

The results were that having the local therapy (breast surgery) did not result in women living longer or having a better quality of life. The overall survival and progression-free survival (meaning the length of time on a particular treatment before the cancer began to grow) were the same for both groups.

What does this mean if you've been diagnosed with de novo metastatic breast cancer?

First, there is now evidence that local treatment to the breast should not be offered with the hope of lengthening life. Sometimes there are good reasons to recommend breast surgery or radiation to manage discomfort caused by the tumor. Secondly, the study confirmed the value of ongoing chemotherapy and targeted therapies in this situation.

It is easy to find this study disappointing and discouraging. However, this study confirmed the value of the existing standard of care and helps us understand what works and what does not work. No one wants to put anyone through surgery, radiation, or any treatment that will be stressful and maybe painful unless there is a good chance of it being helpful.

Although we all continue to hope for new and better ways to treat metastatic breast cancer, we now know that adding local treatment will not bring a benefit. Sometimes continuing on with the standard course of care is truly the best choice.