Childhood leukemia: how a deadly cancer became treatable

Before the 1970s, most children affected by leukemia would quickly die from it. Now, most children in rich countries are cured.

In the past, when I’d hear the words childhood leukemia, I’d picture a young child who suddenly became seriously ill, and whose parents were told their child had only a few years to live.

I’d wonder how a child might grasp the idea of limited time, or how painful it must have been to face the possibility of missing out on growing up, discovering who they are, and forming deep friendships. It would also be a tragic experience for their family, friends, and classmates, who might struggle to understand what’s happening.

This picture, reflected in films, books, and television, depicts what used to be a grim reality. Childhood leukemia was fatal for the vast majority of children who developed it in the past. Before the 1970s, fewer than 10% of children diagnosed with the disease survived five years after diagnosis.

But since then, this outlook has improved dramatically. In North America and Europe, around 85% now survive that long.¹

What made this dramatic change possible? In this article, I’ll describe the progress achieved and some concrete reasons behind it.

This article focuses on data from North America and Europe; death rates from childhood cancers have also declined in other world regions, but remain higher.

Many different types of cancer can affect children. This article focuses on leukemia, the most common type of childhood cancer.

In the chart below, you can see the reduction in cancer death rates in the United States among children of different ages. The decline has been particularly large for leukemia, with a 14-fold drop, but we’ve also made much progress on other, less common childhood cancers.

Explore the data for other countries in an interactive chart.

Leukemia is a cancer of the blood and bone marrow — the tissue that produces blood cells. It develops when immature white blood cells grow out of control and crowd out healthy ones, leading to symptoms like fatigue, infections, easy bruising or bleeding, and pale skin.

While leukemia becomes more common with age, it’s the most frequent cancer in children, making up about a quarter of all childhood cancer cases in the United States.² One reason may be that blood-forming tissues are especially active during childhood, when the body grows quickly and needs a steady supply of new blood cells to carry oxygen, fight infections, and form clots. Many of these cells also have short lifespans, and this stage of life is a crucial period for immune system development.³

This is very demanding for the bone marrow, which must constantly produce new cells. Each time a cell divides, there’s a small chance of a DNA error, and the more divisions that occur, the greater the chance that some of these errors will lead to cancer.

There are two main types of leukemia in children. The most common is acute lymphoblastic leukemia (ALL), which starts in early lymphoid cells. The other is acute myeloid leukemia (AML), which begins in other blood-forming cells.⁴

Most childhood leukemia cases result from genetic mutations that develop spontaneously during this rapid cell division, often occurring before birth, while others are due to inherited genetic mutations, which are less common.⁵ While several environmental exposures have been investigated, there hasnʼt been consistent evidence for any environmental causes.⁶

Survival rates for children with leukemia have risen dramatically in the last 50 years.

The chart below plots overall survival rates — the share of children still alive after a given time since their diagnosis. The data comes from trials by the Children’s Oncology Group, which has enrolled tens of thousands of children since the 1960s, and now includes over half of all children with leukemia.⁷

The top panel displays this for acute lymphoblastic leukemia (ALL) while the bottom panel shows acute myeloid leukemia (AML).

In the top panel, you can see that in the 1960s, only around 14% of children with acute lymphoblastic leukemia survived at least five years. Despite initially improving upon treatment, most relapsed and died soon after.

By the 2010s, the chances of survival had increased dramatically: 94% of children survived at least five years.

Some might wonder whether treatment only delays death rather than being a cure. However, researchers have also analyzed survival rates over the long term and found large improvements: the chart shows that most children are still alive ten years after diagnosis. After the initial years of treatment, their long-term survival is much more stable.

The bottom panel of the chart shows the improvement for acute myeloid leukemia. This subtype, which makes up about 25% of childhood leukemia cases, is more challenging to treat than acute lymphoblastic leukemia. Survival rates for this form have also improved, though not quite as dramatically.

In the 1970s, just 14% of children with acute myeloid leukemia survived at least five years. Now, over 60% do.

This improvement in survival reflects the impact of intensive treatment regimens. These treatments usually still involve years of intensive chemotherapy, which is often physically and mentally challenging and can cause long-term side effects. However, chronic health problems after treatment have become less common, and the long-term health of these children has improved significantly.⁸

This dramatic improvement in survival rates is reflected in the large declines in death rates we saw in the previous section.

You may notice from the chart above that much of this progress has been continuous. Progress in treating leukemia hasn’t come from a single breakthrough but from a series of advances building on one another.

Before the 1940s, children with leukemia usually died within a few weeks of diagnosis, and only comfort care was available. The first chemotherapy agents — aminopterin and, later, 6-mercaptopurine — could briefly eliminate leukemia cells. They gave families hope, but the cancer almost always returned.⁹

Chemotherapy is better tailored to each child

Researchers identified more drugs during the 1950s and early 1960s. Then they took the next logical step: giving several medicines together as a combination and using cranial radiation on spinal fluid — that is, targeting the brain and spine with radiation to kill hidden cancer cells. This helped eliminate leukemia cells that remained in the central nervous system, and doctors began to notice that a small number of patients were being cured.

The 1960s and 1970s saw another breakthrough. Researchers tried “multi-phase” chemotherapy regimens, where treatment was given in four key stages — induction, consolidation, delayed intensification, and maintenance — typically over two to three years. Each phase uses combinations of chemotherapy drugs to eliminate leukemia cells and prevent relapse.¹⁰ In clinical trials, these regimens were successful, seeing survival rates of more than 50%, and hospitals in both North America and Europe ran similar studies and adopted the regimen.¹¹

In the 1980s and early 1990s, researchers found that intensive chemotherapy directed at the spinal fluid could protect the brain just as well as cranial radiation, but with far fewer long-term side effects.¹¹

By the mid-1990s, it also became clear that a single regimen didn’t fit everyone. Large trials sorted children into risk groups (this is called “risk stratification”) based on their age, white blood cell counts, and early genetic findings. Researchers found that lighter chemotherapy could spare the low-risk group from side effects, while stronger chemotherapy could save many in the high-risk group.¹²

Laboratory science then gave doctors even sharper diagnostic tools. For example, tests of “measurable residual disease”, which became widely used in the early 2000s, can spot a single leukemia cell among 10,000 normal cells and help guide further treatment — such as whether to dial treatment back or trigger extra therapy.¹³

All of this showed that large improvements came not just from inventing new drugs, but from optimizing how existing drugs were used. This included finding the right combinations and dosages for different risk groups, adjusting treatment timing and duration to minimize toxic side effects, and identifying subgroups that could safely receive less intensive chemotherapy.

But how did researchers learn which treatment strategies work best?

A key reason was widespread collaboration in clinical trials and research networks.

Large collaborations made better research possible

Childhood leukemia is rare, so it’s very unlikely that a single hospital will see enough cases to draw strong conclusions on its own. To overcome this, researchers formed large collaborative groups and enrolled thousands of children in research studies and clinical trials. These trials helped test which regimens were safer and more effective.

Since then, research groups merged into even larger collaborations to run bigger clinical trials, like the Children’s Oncology Group in North America and the International BFM Study Group in Europe.¹⁴ Over 50% of children with leukemia in the US are enrolled in clinical trials.⁷ This coordination has been crucial in increasing survival rates.

It has helped increase “statistical power” — the ability to detect differences between treatments. It also helped address another challenge: before these clinical trials, treatment was highly variable, with different doctors and hospitals using protocols that were often suboptimal, and survival rates varied widely.

The result was better treatment standards, refined chemotherapy regimens, and reduced harmful practices. One example I mentioned earlier was cranial irradiation, which was once commonly used to prevent leukemia from spreading to the brain. Although it was effective, it carried serious long-term risks, including cognitive impairment and growth problems. Based on the results of these trials, it has now been largely replaced by less toxic chemotherapy-based strategies.¹⁵

Breakthroughs in genetic and molecular research led to further progress

Advances in genetic and molecular research have also transformed the treatment of childhood leukemia. By uncovering which genetic mutations drove different subtypes of the disease, researchers could better identify which children were likely to benefit from standard therapy, and which needed more intensive chemotherapy or other types of treatment, as part of the “risk stratification” approach mentioned earlier.

The research also led to targeted drugs to block some children's specific cancer mutations. One prominent example was imatinib (“Gleevec”), a drug initially developed for chronic myeloid leukemia in adults. It blocks a mutant protein that triggers leukemia cells to multiply rapidly. Although only a small percentage of children with leukemia have this mutation, their survival used to be very poor, and they often needed bone marrow transplants. When imatinib was added to chemotherapy regimens in the 2000s, their survival improved dramatically, and many no longer needed a transplant.¹⁵

More recently, new immunotherapies have reshaped treatment, including CAR-T cell therapy and antibody therapies.¹⁶

Better supportive care helped children

While chemotherapy, targeted therapy, and immunotherapy get much of the attention, better supportive care has also been critical in treating childhood leukemia. This is important because chemotherapy can harm vital organs and suppress the immune system, so children need protection from infections, bleeding, and complications.

Over the last few decades, new treatments and vaccines have helped protect children against these other complications, including:

• Routine platelet transfusions. Before the 1970s, low platelet counts caused fatal bleeds in the brain or gut during intensive chemotherapy. Once blood banks learned to collect and store platelet concentrates at room temperature, daily blood transfusions became practical and deaths fell.¹⁷
• Antibiotics, antifungals, and antivirals to prevent and treat infections, which are a major cause of early deaths during chemotherapy. Recently, more treatments have been approved and added to standard care for leukemia.¹⁸
• Expanded use of vaccines to protect children with weakened immune systems. Over the past few decades, new vaccines — for example, against pneumococcal disease, chickenpox (varicella), and rotavirus — have helped prevent common but potentially serious infections in children with cancer. Some vaccines are recommended for patients themselves, while others are for family members and caregivers to reduce the risk of passing infections.
• Stem cell transplantation is still reserved for the hardest cases, but how it’s done has changed. Years ago, doctors performed transplants with full-body radiation and often reinfused the child’s cells — both practices raised long-term risks and could risk cancer cells sneaking back in. Today, they usually give high-dose chemotherapy instead of radiation, and use stem cells from another donor, which can also help hunt down remaining leukemia cells.¹⁹

For families today, a diagnosis of childhood leukemia is no longer the terrifying death sentence it once was. Most children now survive, complete treatment, return to school, and grow up being able to look forward to longer, healthier lives.

The experience is still incredibly difficult. Hospital visits, harsh side effects, and long periods of uncertainty take a serious emotional toll. Not every child is cured, and there are long-term risks from treatment, though these have been reduced as well.

The impact of this progress is undeniable. Children now live longer and healthier, and their families can hope for and plan for the future in ways that weren’t possible just a few decades ago.

The story of childhood leukemia shows how science, collaboration, and persistence can turn a deadly disease into a largely treatable one. In just decades, it has gone from one of the most feared childhood illnesses to one of the most treatable cancers, and it’s a model for what medical research can achieve.

The next big challenge is ensuring that these advances reach children everywhere. This article has focused on progress in high-income countries, but access to timely diagnosis and treatment is still limited in many parts of the world. Expanding access globally is essential so that every child, no matter where they live, has the chance to live a long life.

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