Oligometastatic breast cancer

Advances in the management of breast cancer are soaring. Gone are the days when doctors, when diagnosed with relapse or metastases, immediately turned to palliative treatment. "In 40% of all metastatic breast cancers, the number of distant metastases is limited to five or less," Dr. Astrid Van Hoyweghen, radiologist at AZ Turnhout told a breast cancer conference* in Vilvoorde. "That's what we call oligometastases ('oligo' means 'single,' n.v.d.r.)." They are a kind of intermediate stage between non- metastatic and metastatic breast cancer. Doctor Van Hoyweghen was one of the speakers at the annual conference of the Belgian Society of Senology, on Jan. 11, 2025 in Vilvoorde. These conferences are heavily attended by Belgian breast cancer experts. Pink Ribbon was there, at the invitation of professor and breast cancer expert Patrick Neven, president of the Belgian Society for Senology. So we can keep our finger on the pulse for you.

New insights are shared

Oligometastases are now examined piece by piece and treated appropriately, we learn. This has dramatically improved the chances of survival for these women. Doctor Jelle Verhoeven, radiotherapist at UZ Leuven (the department where cancer patients are irradiated), explains that there are no guidelines yet for doctors on how best to treat oligometastases. Breast cancer experts from home and abroad are constantly putting their heads together and exchanging experiences. The concept of treating oligometastatic breast cancer separately is therefore quite new. What is already known is shared. For example, the number, location and nature of the metastases play a role. That it should be a maximum of five metastases is not set in stone. "That number is arbitrarily chosen," says Dr. Verhoeven, "the fewer there are, the better of course." It is very important to identify the nature of the metastases. Metastases from breast cancer do not necessarily have the same characteristics as the original tumor. For example, a metastasis may not be hormone-sensitive, whereas the original breast cancer was.

Systemic therapy

All treatments used for a primary breast cancer are eligible for the management of oligometastases: surgery, radiation, chemotherapy, hormone therapy, immunotherapy... Professor Dr. Pierre Foidart, of CHU Liège, explains that systemic therapy is the cornerstone for the treatment of oligometastases. Systemic therapy is all cancer drugs, which includes chemotherapy, hormone therapy, immunotherapy, targeted therapy,... According to Foidart, systemic therapy can sometimes even increase survival by more than 10 years. At best, because a number of influencing factors do appear to play a role. The location of the metastasis, for example. "A metastasis in the bone is more treatable than a metastasis in the brain," says Professor Foidart. "Well-defined metastases also respond better than diffuse metastases in the lung membranes or in the peritoneum, for example." And those with only one or two metastases also have better odds.

Forecast

In any case, the thorough treatment of oligometastatic breast cancer means that the patient has to go through another tough treatment regimen, sometimes for several metastases in succession. That creeps in and needs to be talked through properly. Moreover, one does not always know what the outcome will be. On top of that, new cancer drugs are emerging all the time, which in all likelihood can also be used for oligometastases. This is good news. For example, for triple-negative breast cancer, there are products in the pipeline that are hopeful not only for this type of breast cancer, but also for oligometastases that are not hormone-sensitive. In short, breast cancer treatment is evolving. This was demonstrated once again at this conference with many enthusiastic physicians. Breast cancer patients in Belgium are not alone. They are being thought of.

*Managing unusual breast cancer cases. Belgian Society of Senology Conference. Living Tomorrow Vilvoorde, January 11, 2025.