COLUMBUS, Ohio -- One of the longest running studies to follow leukemia patients has confirmed that chromosomal abnormalities seen in many of these patients can help determine treatment and predict the likelihood of cure.
The study is a 15-year follow-up of 628 patients with acute myeloid leukemia (AML). This was the first large group of AML leukemia patients for which information on chromosomal abnormalities was prospectively collected. The study of chromosomal abnormalities is known as cytogenetics.
“This study provides stronger evidence for the correlation between cure and a patient’s cytogenetics, and between cytogenetics, survival, and the treatment that patients receive,” said Clara Bloomfield, director of the Ohio State University's Comprehensive Cancer Center and William G. Pace III Professor of Cancer Research.
“It also showed that the majority of patients who were continuously disease-free for five years after diagnosis were cured.”
The study, which was led by Bloomfield, appears in a recent supplement to the journal Cancer. The 628 patients, median age 49 years, had primary AML that was diagnosed between 1980 and 1982.
Median survival of the patients was 7 months, although survival varied significantly according to the chromosomal abnormalities present. For example, patients whose leukemia cells showed a loss of, or damage to, one of the two copies of chromosome 5 or 7 had a median survival of 3 months, while those showing damage to chromosome 16 had a median survival of 18 months.
Of the 628 AML patients in the study, 56 (9 percent) were alive five years after diagnosis. Of these, nine died of AML between 5 and 10 years, one died of AML 11 years after diagnosis, and 7 seven were unavailable for further follow-up.
This left 39 patients, or 6.2 percent, alive 10 to 15 years after their AML diagnosis.
“These data are among the first to confirm that a percentage of people with AML are cured,” she said. “They also show that whether patients are cured or not depends on the type of leukemia they have as determined by cytogenetics and on the type of treatment they receive.
“It’s important to remember that these patients were treated between 1980 and 1982,” said Bloomfield. “The treatment received by AML patients today results in a much larger number of long-term disease-free survivors.”
For example, the drugs used today are more effective, and the way they are used is also different.
Today, the initial chemotherapy treatment (known as induction therapy) given patients with primary AML produces complete remission in about 60 percent of patients. During remission, patients are then usually given courses of high-dose chemotherapy that are designed to eliminate remaining cancer cells. This second plan of treatment is known as intensification therapy.
Stem-cell transplantation is another line of therapy available to AML patients whose disease doesn’t respond well to chemotherapy.
A patient’s cytogenetics helps determine treatment by identifying the subtypes of leukemia that are likely to respond to a certain type of therapy and those that probably won’t. For example, a patient with cytogenetics that shows a good prognosis (such as damage to chromosome 16, as mentioned above) might receive today’s standard therapy. A patient with cytogenetics that indicates a poor prognosis might be recommended for stem-cell transplant or an experimental therapy.
“Intensification therapy and stem-cell transplantation are the two main things that are done for patients today that were not done for the patients in this study,” said Bloomfield.
“Today probably about 40 percent of patients with primary AML who achieve complete remission are cured. It’s a big difference.”
Contact: Clara Bloomfield, (614) 293-7048; Bloomfield-1@medctr.osu.edu
Written by Darrell E. Ward, (614) 292-8456; Ward.25@osu.edu
Journal
Cancer