A newly published Croatian case illustrates how challenging it can sometimes be to distinguish between breast cancer and mesothelioma.
The case involves a 61-year-old woman with what appeared to be breast cancer. Further study revealed that what the woman actually had was pleural mesothelioma. The mesothelioma had spread to her breast.
Breast cancer and mesothelioma cells look similar under the microscope. But they are very different. The authors of the new report caution doctors against the “pitfall” of mistaking one for the other.
Breast Metastasis is Rare
Pleural mesothelioma occurs on the membrane that surrounds the lungs. It is rare for mesothelioma to spread to the breast. The most common place for mesothelioma cells to spread is the lungs.
Women are more likely to get breast cancer and mesothelioma is more common in men. Only about 0.5% to 6.6% of breast malignancies start in another part of the body.
In addition, asbestos is the main cause of mesothelioma. It was mostly used in male-dominated industries like construction.
These are all reasons why doctors may not think about mesothelioma when they find cancer in a woman’s breast. But that oversight can be costly.
“The epithelioid type of MPM can represent a diagnostic pitfall in this setting,” writes lead author Lea Korša, of University Hospital Centre Zagreb. “It shows similar histologic features to primary breast carcinoma as well as other metastatic epithelioid malignancies.”
Distinguishing Between Breast Cancer and Mesothelioma
Why does it matter whether doctors distinguish between breast cancer and mesothelioma? Because the two types of cancer have different treatments. They also carry different prognoses.
Malignant mesothelioma is one of the rarest and most difficult cancers to treat. Primary breast cancer usually responds well to chemotherapy and radiation. But mesothelioma is often resistant to both. Many patients die within a year of a mesothelioma diagnosis.
One of the main ways to tell the difference between primary breast cancer and mesothelioma in the breast is through patient history.
If a patient worked around asbestos, they could have mesothelioma. Smoking increases the risk. If doctors have this information about patients, they are less likely to miss metastatic mesothelioma in the breast.
Italian researchers published a similar case study in 2015. In that case, a 49-year-old hairdresser had a large mass in her right breast.
Doctors ruled out breast cancer and mesothelioma was diagnosed after estrogen and progesterone receptors were negative. The woman probably inhaled asbestos fibers from working with asbestos-containing hairdryers.
Korsa, L, et al, “Breast Metastasis as the Initial Presentation of Malignant Pleural Mesothelioma”, May 30, 2020, The Breast Journal, Epub ahead of print, https://onlinelibrary.wiley.com/doi/abs/10.1111/tbj.13898
Framarino-Dei-Malatesta, M, et al, “Breast cancer or metastasis? An unusual case of metastatic malignant pleural mesothelioma to the breast”, February 25, 2015, World Journal of Surgical Oncology, Epub ahead of print