Although initial clinical trials of tamoxifen as a treatment of breast cancer were positive, Imperial Chemical Industries (ICI) did not believe this market would be commercially viable. The company had hoped for a contraceptive pill – tamoxifen didn’t work for that – not a cancer treatment. In 1972 the higher-ups at ICI decided to cancel the research.‍

But Dora Richardson, the chemist who had originally synthesized the compound, and her boss, Arthur Walpole, were convinced they were on to something important, something that could save lives. They continued the research in secret. Tamoxifen was eventually launched in 1973 and went on to become a global success, saving hundreds of thousands of lives. Dora Richardson’s role in its development, however, was overshadowed by her a male colleague and all but forgotten.

This Best Of episode first aired in October 2024 to coincide with Breast Cancer Awareness month. It is now also available in a Spanish adaptation, narrated by Laura Gómez.