The Glow-in-the-Dark Salt Extracted by Boiling Tons of Rock in a Shed: Radium

Marie Curie, the Discovery of Radium and Cancer Treatment’s First Radioactive Weapon

Occupied Poland, a secret university and the Sorbonne

Maria Salomea Skłodowska was born on 7 November 1867 in Warsaw, then under occupation by the Russian Empire. Her father was a physics and mathematics teacher and her mother was the headmistress of a girls’ school; but Marie lost her mother to tuberculosis when she was only 10. In Russian-occupied Poland, women were forbidden to attend university; Marie and her older sister Bronisława joined the underground educational network known as the "Flying University" (Latający Uniwersytet), which operated secretly and changed locations to evade the Russian authorities.

The two sisters made an agreement: Marie would earn money as a governess to finance Bronisława’s medical studies in Paris; then Bronisława would support Marie in coming to Paris to study. The plan worked. In 1891, at age 24, Marie arrived in Paris and enrolled at the Sorbonne(University of Paris). She studied in poverty in a cold attic, sometimes fainting from hunger; yet she graduated at the top of her class in physics in 1893 and mathematics in 1894.

In 1894, while looking for a laboratory to work in, she met the French physicist Pierre Curie — a calm man devoted to science who studied crystal physics and magnetism. They married in 1895; it was the beginning both of a love story and of one of history’s most productive scientific partnerships.

From Becquerel’s strange observation to a doctoral thesis

In 1896, inspired by Röntgen’s X-rays, Henri Becquerel was investigating whether phosphorescent substances (substances that glow after exposure to light) emitted X-rays. He placed uranium salts over photographic plates and noticed that uranium darkened the plate even without any exposure to light. In other words, uranium spontaneously emitted continuous radiation. Becquerel published the observation but did not pursue it further — and the scientific world showed little interest.

For her doctoral thesis, Marie Curie chose these "Becquerel rays". Using a sensitive electrometer (an instrument measuring electric charge) developed by Pierre, she measured how uranium’s radiation ionized the air. She worked systematically: the radiation’s intensity depended only on the amount of uranium — temperature, light and the chemical compound made no difference. This led to a groundbreaking inference:

In April 1898, Marie gave this phenomenon a name: radioactivité. Then she turned her attention to the uranium ore pitchblende(uraninite). Here she found something unexpected: pitchblende was four to five times more radioactive than the pure uranium it contained. It made no sense. The only explanation was that pitchblende must contain an as-yet undiscovered element even more powerful than uranium.

The old hangar on Rue Lhomond and four years of chemical labor

Becquerel, Pierre and Marie — and the name almost excluded

In 1903, the Nobel Prize in Physics was awarded to Henri Becquerel and the Curie couple for their research on radioactivity. But one detail starkly reveals the gender barriers of the time: the French Academy of Sciences initially nominated only Becquerel and Pierre Curiefor the prize — Marie’s name was not on the list. Knowing that his wife had been the principal investigator of this work, Pierre Curie stated that he would not accept the prize without Marie . Marie was then included in the award and became the first woman in history to win a Nobel Prize .

Beneath a horse-drawn cart on a rainy day in Paris

On 19 April 1906, while walking along a rainy Paris street, Pierre Curie lost his balance on the slippery surface and fell in front of a heavy horse-drawn cart; a wheel passed over his head and he died instantly. He was 46. In a moment, Marie lost the love of her life and her scientific partner.

Despite this devastating loss, Marie did not stop. The Sorbonne gave Marie Pierre’s vacant professorship — for the first time in history, to a woman. She officially became a professor in 1908 and continued the course Pierre had started from where he had left off. She continued purifying radium and studying its properties with her faithful assistant André Debierne.

A second Nobel Prize in the shadow of a scandal

In 1911, Marie Curie received the Nobel Prize in Chemistry, this time on her own— for "the discovery of the elements radium and polonium, the isolation of radium, and the study of the nature and compounds of this remarkable element". This made her the first person to win Nobel Prizes in two different scientific disciplines.

However, the award came in the shadow of a scandal. At the time, it had been leaked to the press that Marie was having an affair with Pierre’s former student, the married physicist Paul Langevin; the conservative French press conducted a campaign of vilification centered on the theme "foreign, Polish, widowed woman". Some Nobel Committee members suggested she should not come to Stockholm under the shadow of the scandal. Marie’s response was clear and dignified: stating that the prize had been awarded for her scientific achievement and that her private life had nothing to do with it, she went to Stockholm and accepted the prize.

The "glow-in-the-dark salt" becomes a treatment weapon

The discovery of radium opened a direct door for cancer medicine. Like X-rays (day 81), the radiation emitted by radium was soon found to damage biological tissue. In an experiment, Pierre Curie himself deliberately exposed his arm to radium and examined the resulting scar (a burn-like lesion) — early evidence that radium could destroy living tissue.

The reasoning quickly followed: if radium could damage healthy tissue, perhaps it could also destroy malignant tumor tissue. As early as 1899, a malignant skin tumor was reported to have been cured through the application of a radioactive source. Thus a new branch of cancer treatment was born:

Marie Curie saw and supported radium’s medical value, but never patented it. She made the method of isolating radium freely available to everyone — like Röntgen’s refusal to patent X-rays (day 81), in the belief that scientific knowledge should belong to humanity.

Mobile X-ray vehicles traveling to the front

When World War I broke out (1914), Marie Curie set aside her scientific career and turned to the war effort. She knew X-ray imaging could save lives by locating bullets and shrapnel inside wounded soldiers. She designed mobile X-ray units — portable radiology units mounted on cars and equipped with generators. These vehicles became popularly known as "petites Curies" (little Curies).

Marie did more than design them; she learned to drive herself, drove to the front, trained radiology technicians and, together with her daughter Irène , performed X-rays in frontline hospitals. Approximately 20 mobile units and 200 fixed radiology stations were established during the war; it is estimated that more than a million wounded soldiers were imaged with this system. This was the first large-scale field application of medical imaging.

The arrival of radium and radiotherapy in Türkiye

Radioactivity and the medical use of radium reached Ottoman and early Republican medicine in the first half of the 20th century. The institutionalization of modern radiotherapy in Türkiye accompanied the Republic’s advances in health care: university hospitals in Istanbul and Ankara installed radium tubes first, then (from the middle of the 20th century) cobalt-60 devices and linear accelerators. The institutional history of the Turkish Society for Radiation Oncology forms the professional backbone of this development.

In contemporary oncology practice, radiation oncology is one of the three main pillars of cancer treatment alongside surgery and medical oncology. Adjuvant radiotherapy after surgery for a breast cancer patient, brachytherapy for a cervical cancer patient, ⁱⁿ⁷⁷Lu-PSMA radionuclide therapy for a prostate cancer patient — all are the direct legacy of Marie Curie, boiling tons of rock in a Paris shed in 1898. The radiation oncologist’s seat at modern multidisciplinary tumor boards is today’s extension of this 125-year lineage.

This article is day 82 of the Cancer History in 365 Days Series. Marie Curie’s discovery of radioactivity and radium is a cornerstone of modern radiation oncology (radiotherapy, brachytherapy/Curie therapy, nuclear medicine and radiopharmaceutical treatment). Together with Röntgen’s discovery of X-rays (day 81), radiation became the basis of cancer diagnosis (imaging), cancer treatment (radiotherapy) and, tragically, radiation-induced cancers and diseases; this threefold nature is at the ethical and technical center of radiation science. Marie Curie’s death from radiation-related aplastic anemia and early radiation tragedies such as the "Radium Girls" led to the development of modern radiation safety science (radiobiology, dose limits, the ALARA principle). This sensitive subject is presented in balanced language to inform readers who have concerns about radiation. In contemporary oncology practice, radiation oncology is one of the three main pillars of cancer treatment alongside surgery and medical oncology. This article takes a popular historical perspective; it contains no guidance on medical treatment. All dates, biographical details and scientific data in the article have been verified from Ève Curie’s 1937 biography, the Quinn 1995 and Goldsmith 2005 biographies, official Nobel Foundation records, Mould’s 1993/1999 medical history studies, Britannica and modern academic sources.