Leukemia, once regarded as an incurable disease, is turning into "a cancer that can be cured" thanks to advances in diagnostic and treatment technology. Leukemia is known as "cancer of the blood." It develops when hematopoietic stem cells in the bone marrow — the factory that produces blood — turn into cancer cells and generate abnormal blood cells (white blood cells, red blood cells, platelets). While solid tumors begin in a single organ and progress and spread, leukemia has the characteristic that cancer cells have already spread throughout the body via the blood from the moment of diagnosis.
Back in the 1970s, there were few ways to treat leukemia, and most patients died. But today the situation has completely changed. Along with a variety of drugs, the development of technology to transplant healthy hematopoietic stem cells from other people has greatly increased treatment success rates.
Cho Byung-sik, Director of the Leukemia Center at the Catholic Hematology Hospital of Seoul St. Mary's Hospital and a professor of hematology known as a "leukemia authority," said, "Leukemia was regarded as an incurable disease in the past, but with recent advances in treatment technology, treatment outcomes have improved so much that a considerable number of patients, even elderly ones, can be cured." According to statistics from the National Cancer Information Center, 60 to 70 percent of leukemia patients are known to be cured.
On Seoul Economic Daily TV's "Now, the Authority," airing at 9 p.m. on Sunday, Professor Cho appears to explain the causes and symptoms of leukemia and the latest treatments.
◇ Acute Myeloid Leukemia Common in Adults
Acute leukemia is broadly divided into "acute lymphoblastic leukemia (ALL)" and "acute myeloid leukemia (AML)." In children, acute lymphoblastic leukemia is common and tends to respond well to chemotherapy. In adults, acute myeloid leukemia is more common and occurs especially in the elderly.
The causes of leukemia are mostly unknown. "High-dose radiation exposure, secondary leukemia after chemotherapy, and exposure to organic solvents such as benzene are known risk factors," Professor Cho said. "However, in most cases leukemia develops without any such history of exposure." He added, "Leukemia risk rises with age. As people grow older, genetic damage to hematopoietic stem cells accumulates and is believed to transform them into cancer cells."
Hereditary leukemia is rare. Professor Cho explained that the main purpose of genetic testing in leukemia patients is not to check whether the disease is passed from parent to child, but to identify genomic mutations in the leukemia cells in order to establish a treatment strategy.
◇ When Anemia, Bruising, and Infections Recur, Start With a Blood Test
It is hard to say leukemia has any specific symptoms. However, when red blood cells fall, anemia symptoms such as fatigue and shortness of breath appear; when platelets fall, bruising and bleeding occur; and when white blood cell function is impaired, unexplained fever or infections can recur. "These symptoms can arise for other reasons too, so it is hard to call them symptoms of leukemia, but if you feel something wrong with your body for no reason, I recommend checking for blood cell abnormalities through a simple blood test (CBC) at a nearby hospital," Professor Cho said.
◇ When Chemotherapy Does Not Cure, Stem Cell Transplantation
For acute myeloid leukemia, the most common type in adults, chemotherapy is the standard. The intensity of chemotherapy varies from patient to patient. Chromosome testing and next-generation sequencing (NGS) analysis are performed on leukemia cells obtained through bone marrow examination, classifying prognostic groups (good, intermediate, poor) before establishing a tailored treatment strategy. "In good-prognosis types, a cure without recurrence can be expected with chemotherapy alone," Professor Cho said. "For intermediate and poor types, we establish a strategy that leads to allogeneic hematopoietic stem cell transplantation after chemotherapy."
Allogeneic hematopoietic stem cell transplantation is a treatment that transplants healthy hematopoietic stem cells from another person. In the transplantation process, the patient's bone marrow and leukemia cells are first removed, then the donor's hematopoietic stem cells are infused through a blood vessel. The donor's stem cells settle in the patient's bone marrow, attacking the leukemia cells remaining in the patient's body while at the same time producing new blood cells.
Allogeneic hematopoietic stem cell transplantation is an effective treatment, but half of transplant patients develop a complication called "graft-versus-host disease (GVHD)." GVHD is a complication in which the donor's immune cells attack the patient's normal tissues, such as the skin, intestines, and liver, causing an inflammatory reaction.
Good drugs have also emerged for GVHD, improving the treatment outlook. "The first-line treatment for GVHD is high-dose steroids, but recently the targeted immunomodulator 'Jakavi (a JAK inhibitor)' has come into use, increasing the options," Professor Cho explained. "For cases that do not respond even to Jakavi, we use a treatment called 'Rezurock (a ROCK2 inhibitor),' and with the recent expansion of insurance coverage, treatment outcomes have become better than in the past."
◇ Elderly Patients Also Get Stem Cell Transplants, Raising Survival Rates
In the past, only young and healthy patients could undergo hematopoietic stem cell transplantation, but recently transplants have been expanding among the elderly as well. "The biggest change is that elderly patients can now undergo transplantation by using low-intensity chemotherapy for conditioning regimens," Professor Cho said. "The broadening of the donor pool and advances in drugs to treat graft-versus-host disease, the representative complication, are also reasons behind the expansion of transplants and improved survival rates for elderly patients."
He cited the "introduction of targeted anticancer drugs" as the reason treatment outcomes have improved since 2017 in particular. "For a long time, acute myeloid leukemia had few options other than chemotherapy and transplantation, but since 2017 targeted anticancer drugs have been introduced every year, improving treatment outcomes," Professor Cho explained. "For patients who reach remission after chemotherapy and go on to allogeneic transplantation, six out of 10 can expect a cure even if they are elderly."
On preventing leukemia, Professor Cho said, "There is no clear preventive method," but advised, "Healthy lifestyle habits are important, and if minor symptoms such as unexplained fatigue, bruising, or infections recur, be sure to get a blood test."
Regarding health checkup items, he advised, "It varies by checkup, but you should get a 'CBC' test that examines white blood cells, red blood cells, and platelets together."
"Because of dramas and movies, the misconception remains that leukemia is a hopeless disease, but with advances in targeted therapy, immunotherapy, and precision medicine, tailored treatment plans have become possible, and it has become a disease that can be overcome," Professor Cho stressed. "The treatment process is long and not easy, but if you endure to the end, you can overcome it."
Leukemia, the "Cancer of the Blood," Is No Longer Incurable [Professor Cho Byung-sik, Department of Hematology, Seoul St. Mary's Hospital]
