How is it that breast cancer, in spite of all the pink, can still become Metastatic Breast Cancer (MBC), and can still “spread,” “come back,” and take too many lives? Here are 5 things you may not know.

1. Breast cancer can be a fugitive. After a diagnosis of breast cancer, local therapy like surgery and radiation remove the cancer cells from the breast. Many years ago, it was believed that if the tumor was small and the surgeon “got it all,” the patient was cured. But we now know that even sometimes in early stage cancers, breast cancer cells can sometimes escape the breast and travel throughout the body via the lymphatic system and bloodstream, looking to set up shop somewhere else. Scientists are working on the technology—think an ankle-bracelet system—to keep tabs on any such cancer cells, to know if any have escaped. Until then, most breast cancer patients must undergo whole-body treatment – like hormone therapy or chemotherapy – to try to catch any fugitive cells on the run, before they cause trouble elsewhere.

2. Breast cancer can be a squatter. When breast cancer spreads to a new place in the body, even many years later, it is because the fugitive cells escaped the breast and, having arrived at a new place, laid low, tried to fit in, and adapted to their new environment until they could survive there, too. Aggressive, fast-growing cancers do this more quickly, tending to show up within 3-5 years, while more slow-growing cancers can mosey along at this process for as long as 10 or even 20 years. This is why breast cancer providers avoid proclaiming their patients “cured”, why five years breast cancer-free is no guarantee, and why even early-stage survivors often struggle to shake a deep and persistent fear of recurrence.

3. The answers to hair-raising questions. Increasingly, breast cancer treatments are tailored to the specific characteristics of the tumor, and many treatments, such as hormone therapy and targeted therapy and even some kinds of chemotherapy, do not cause hair loss. Hair loss is not a good indicator of stage or extent of disease or of how a patient is responding to treatment. Just because a breast cancer patient still has her hair does not mean that her cancer has not spread or that she is finished with treatment.

4. Metastatic breast cancer is treatable, but not curable. Sometimes, breast cancer is metastatic right from the beginning. Other times, breast cancer shows up elsewhere in the body some time after the initial diagnosis. Either way, once breast cancer has been found to have spread, it is said to be treatable but not curable. Hopefully, this will not long be the case, as clinical trials continue to promise and develop new treatments and provide increasing hope for the future. Many MBC patients today live with their disease for a long time, in a way that is not exactly the same but is often most easily compared to living with a chronic illness.

5. She (or he) will never be “done” with treatment. MBC patients will be in treatment for the rest of their lives. Cancer is a shape-shifter, changing and finding ways to survive even in increasingly hostile environments, and this means that cancer cells living outside the breast can adapt and become resistant to treatments which worked well in the past. Living with MBC means living with the knowledge that even effective treatments may one day stop working, the uncertainty of when that will come and what that will mean, of how many potential treatments remain, and of what the side effects of those will be can be very difficult. For all of these reasons, clinical trials for MBC remain the hope for a better life for those learning to live with MBC, and for many more who—we hope—will never have to.