Henrietta Lacks, who would one day become known for her unintended contribution to medical science.

In 1951, a 31-year-old mother-of-five walked into Maryland’s Johns Hopkins Hospital for what she called “a knot on my womb”. The knot, it turned out, was a virulent cancer that had started in her cervix. She would soon die in agony of the disease, then the number one killer of American women. The woman was Henrietta Lacks, who would one day become known for her unintended contribution to medical science. After her death, scientists would take her cancer cells and reproduce them into perpetuity without her family’s knowledge, using them to investigate diseases from Aids to polio. If Lacks had been given a Pap smear, she may have survived. Developed a decade earlier, the simple screening tool – named after its creator, Greek gynaecologist George “Pap” Papanicolaou – was the newest and most promising technology in early cancer detection. It rose to become the gold standard in cancer screening, and would be instrumental in slashing cervical cancer rates by 70% over the next half century. But its benefits were not applied equally. In the 1950s United States, the face of cancer prevention campaigns was a well-to-do white woman; reproductive cancer in black women was all but invisible. (Even when the magazine Colliers told the story of Lacks, whom they called “Mrs L”, they pointedly left out her race.) Far fewer black women got the test, either because their doctor never offered it or because they didn’t know to ask. You might also like: The woman who changed human fertility forever How a black science pioneer was failed The woman who saved 90,000 infants Yet at the same time that Lacks’ tumour was growing, a gynaecologist named Helen Octavia Dickens was driving around Philadelphia in an American Cancer Society van, giving black women free Pap smears. She parked her van at local churches, and invited women to come inside for what she described as “a painless, simple, five-minute procedure”. Many times she found cancer and was able to operate, turning those patients into lifelong devotees. Getting them to enter the van, however, was no small feat. Besides the silence surrounding cervical cancer, Dickens had to overcome a deep and well-founded distrust of the US medical system. Black women, she knew, had good reasons to be wary of getting a pelvic exam from a (usually) white male doctor. These fears went back to James Marion Sims, the Southern doctor dubbed the “father of modern gynaecology,” who purchased enslaved black women suffering from fistulas to experiment on in the days before anaesthesia.