On Monday, the U.S. Food and Drug Administration (FDA) issued a draft guidance calling for greater inclusion of men in clinical breast cancer trials.

Historically, male participation has either been excluded or limited in breast cancer research, making it difficult to predict long-and-short term outcomes for male patients.

“Less than one per cent of all breast cancer cases occur in men, but men are more likely to be diagnosed at an older age and have a more advanced stage of disease,” Richard Pazdur, M.D., director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said in a statement.

While some FDA-approved treatments are gender-neutral in their indication, several therapies are only approved for women, Dr. Pazdur says.

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“As breast cancer in men is rare, they have typically not been included in clinical trials for breast cancer treatment. This has led to a lack of data, so their treatment is generally based upon studies and data collected in women.”

When finalized, Dr. Pazdur says the guidance is expected to “provide clarity for industry regarding how additional data to support efficacy and safety for male patients with breast cancer can be generated through a variety of trial designs using different data sources, including studies using real-world data.”

The full statement can be read on the FDA website.