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Mesothelioma Growth Slowed by Breast Cancer Drug

3011324_biotech2A drug most often associated with the treatment and prevention of breast cancer may offer a new way to treat pleural mesothelioma, too.

A new study conducted by Ireland’s Royal College of Surgeons and published in the medical journal Anticancer Research focuses on tamoxifen as a novel mesothelioma therapy.

How Tamoxifen Works

Tamoxifen helps fight breast cancer and protect high-risk women from getting it by blocking cancer cells from using the estrogen they need to grow.

Given that some types of mesothelioma tumors also appear to rely on estrogen to fuel their growth, the Irish scientists theorized that a drug like tamoxifen, which modulates estrogen receptors, could be used to enhance mesothelioma therapy.

Testing Tamoxifen on Mesothelioma Cells

The researchers tested tamoxifen in four different mesothelioma cells lines in the laboratory. Their goal was twofold – to determine whether tamoxifen could slow the growth of pleural mesothelioma and to see if it could improve the action of mesothelioma chemotherapy.

The four cell lines were treated with a combination of tamoxifen and the platinum-based drug cisplatin, one of the primary components of chemotherapy for mesothelioma patients. The news was encouraging for mesothelioma patients.

“Tamoxifen inhibited the growth of malignant pleural mesothelioma cells and also modulated their sensitivity to cisplatin,” writes study author Cormac Jennings, PhD, a molecular medicine specialist with Beaumont Hospital in Dublin.

A Surprise for Mesothelioma Researchers

Although the news was good, the study also produced some surprises. Even though tamoxifen appeared to work against pleural mesothelioma, it was not in the way the researchers had expected.

Instead of acting on the estrogen receptors in these ER-positive mesothelioma cell lines, tamoxifen repressed the expression of cyclins, proteins associated with cell division. The result was an interruption of the normal cell cycle for these mesothelioma cells and an increase in apoptosis, the natural process of programmed cell death.

“The ER-independent actions of tamoxifen on malignant pleural mesothelioma cell proliferation and cell cycle progression may have clinical benefits for a subset of patients with MPM,” concludes Dr. Jennings.

Tamoxifen has been used to treat breast cancer for more than 40 years. It is available in a generic form and is relatively inexpensive. It has not yet been studied in the treatment of mesothelioma patients.


Jennings, CJ, et al, “Tamoxifen suppresses the growth of malignant pleural mesothelioma cells”, November 2016, Anticancer Research, pp. 5905-5913

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