In 2021, Carol Rosen, a 70-year-old retired schoolteacher, died painfully weeks after a standard metastatic breast cancer treatment. Rosen suffered severe reactions to a chemotherapy drug due to an enzyme deficiency, an issue affecting many cancer patients. Each year, over 275,000 U.S. cancer patients receive fluorouracil (5-FU) or its pill form, capecitabine. Without the enzyme to metabolize these drugs, patients experience overdose-like effects, leading to hundreds of deaths annually. A simple test can identify this deficiency, yet only 3% of U.S. oncologists routinely conduct it, as national guidelines don’t mandate it.
The FDA, criticized for not requiring the test, recently updated 5-FU’s label with warnings but stopped short of making the test mandatory. In contrast, European authorities have recommended this testing since 2020.
Despite scientific advances, many U.S. oncologists are reluctant to change protocols. For example, genetic tests that could prevent toxic reactions from common drugs like clopidogrel are often overlooked. After Rosen’s death, her daughter pushed for routine testing at Dana-Farber Cancer Institute, leading to successful detection of at-risk patients.
The debate continues, with some experts calling for mandatory testing and acknowledging the need for different tests catering to diverse ancestries. Others, like UCSF oncologist Dr. Alan Venook, argue against mandatory testing, fearing undertreatment. However, the rising number of lawsuits and institutional changes might drive a shift towards mandatory testing.
