In the history of medicine there are a few cases that produced the opposite effect to what was initially intended. One such case was the Tamoxifen pill, with a contraceptive compound applicable to the concept of the “morning-after pill”. In other words, the woman had to ingest the tablet hours after sexual intercourse in order not to become pregnant. A decade after its launch, they discovered that it caused the opposite effect, since it favored ovulation.
The “morning-after pill” that proved ineffective.
It was 1962 when a British company (Imperial Chemical Industries) was researching new components for a contraceptive pill. The chemist Dora Richardson tested this new component on rats and the effect was the intended one, contraception. However, ten years later, they confirmed that in humans it did not have the same effect as in rodents. Rather, it turned out to be the opposite, it favored the pregnancies that they were trying to avoid by means of the pill.
The company opted to cease research altogether, however, the project continued due to the persistence of the scientific team leader, Dr. Arthur Walpole. This scientist kept the project active by threatening to resign if the research was not kept ongoing.
They tested the same pill to fight breast cancer.
In parallel to contraception, they tested the famous pill in the treatment of breast cancer. The first trials, dating back to 1971 at the Christie Hospital in Manchester, gave positive results. It also had the advantage of having no side effects. For economic reasons they did not continue with this branch of research. However, the trials carried out with the drug applied to breast cancer resulted in some publications and aroused scientific interest in other parts of the world.
This led the British company to seek to obtain a license in 1973 for the drug, which was given a new name. However, due to lack of funds for further research, the drug was not brought to market. Sadly, Dr. Walpole passed away four years later.
Shortly thereafter, the World Health Organization listed the compound Tamoxifen as essential for the treatment of breast cancer.
Breast cancers with estrogen receptors are known as estrogen receptor-positive cancers, indicating their dependence on this female hormone for growth. The drug is highly effective because it acts as a blocker, slowing tumor growth. This drug binds to the estrogen receptor, inhibiting its function and preventing the tumor from receiving the nutrients necessary for its development.
During 2020, 2.3 million breast cancer diagnoses were reported globally, with more than 70% of these cases classified as estrogen receptor positive. Although Tamoxifen did not fulfill its role as the “morning-after pill,” it plays a critical role in preserving millions of lives.