Cancer of the blood, called leukemia, occurs most often in adults older than 55, but it's also the most common cancer in children younger than 15. When you have leukemia, your body makes too many abnormal white blood cells, which crowd out healthy cells. Treatment for leukemia has come a long way, but here are some things you may not know about the disease.
1. Not all leukemias are alike.
There are two major types of leukemia: acute and chronic. Acute leukemia develops in immature cells, called blasts, and it grows rapidly, requiring immediate treatment. Chronic leukemia develops slowly in more mature cells that can behave normally for long periods of time and then enter a phase where they grow more quickly. Chronic leukemia can go unnoticed for years before it's diagnosed.
2. Different types of leukemia involve entirely different kinds of cells.
Doctors classify leukemia cases based on the kinds of cells that are affected. Two types of leukemia occur within your immune system: acute lymphocytic leukemia (ALL) and chronic lymphocytic leukemia (CLL). The other two types involve myeloid cells, which give rise to blood cells and platelets. They include acute myelogenous leukemia (AML), and chronic myelogenous leukemia (CML).
3. Not all leukemia needs to be treated right away.
People who are diagnosed with a chronic form of leukemia and are not yet showing symptoms may not need immediate treatment. Using an approach called "watchful waiting," doctors monitor the leukemia and, if it becomes more active, will start therapy. People who take this approach can change their mind at any time and request treatment if they become concerned.
4. Children and adults tend to get different kinds of leukemia.
ALL, or acute lymphocytic leukemia, accounts for about three of four leukemia cases in children and teenagers. Most of the other cases are acute myelogenous leukemia, or AML. By contrast, the most common types of leukemia in adults are AML, which tends to develop in older people, at an average age of 67, and chronic lymphocytic leukemia (CLL). Experts don't yet understand why leukemia takes different forms in different age groups.
5. Most children who get leukemia survive.
When it comes to patients with acute lymphocyte leukemia (ALL), more than 90% of patients younger than 15 are alive five years after treatment ends-and after five years, their leukemia is unlikely to return. For children younger than five years old, the five-year survival rate is even higher–almost 93%. Taking into account all forms of leukemia, the five-year survival rate is over 70%. It's a huge step forward since the 1960s, when the survival rate for children with ALL was only 10%.
6. Many adults beat leukemia, as well.
Survival rates in the United States have quadrupled in the past 50 years; today, more than 60% of leukemia patients are alive five years post-treatment. There are more than 345,000 people living with, or in remission from, leukemia in the United States today. In the 1960s, the survival rate was only 15% for groups who were tracked. Even with the significant improvement that recent statistics show, leukemia is currently still one of the top 10 causes of cancer deaths.
7. The rate of developing leukemia has increased slightly.
The overall incidence of leukemia has increased-rising an average of 0.2% each year from 2002 to 2011. However, the death rate has fallen faster, at an average of 1% each year for roughly the same period. Leukemia is a bit more common in men than women, and seen more often in Caucasians than in other races and ethnicities.
8. Leukemia cells don't die naturally.
Unlike normal blood cells, leukemia cells don't die when they become old or damaged, so they can build up and crowd out normal blood cells. The lack of healthy blood cells also makes it harder for the body to get oxygen to the tissues, control bleeding, or fight infections. Leukemia cells can also spread to other organs, such as the lymph nodes, spleen and brain. Chemotherapy and radiation kill cancerous cells, but they kill healthy cells too, which is part of the reason side effects can be significant. Doctors now can prescribe medications to reduce these side effects.
9. The discovery of the "Philadelphia chromosome" was a game changer for leukemia treatment.
The Philadelphia chromosome, named for the city in which it was discovered in 1960, is a marker in almost all cases of CML and some cases of ALL. Identifying it led to breakthroughs in cancer treatment, allowing researchers to develop genetically targeted treatments for people with these types of leukemia. The treatments kill unhealthy cells more precisely and leave healthy cells undamaged, unlike earlier chemotherapies. Some of the side effects of targeted drugs, such as high blood pressure and a kind of skin rash that looks like acne, can actually indicate a good response to the medications.