Chemo after solid tumors linked to higher risk for rare blood cancers

Dec. 20 (UPI) -- Chemotherapy is a common treatment for cancer, but in some cases, it could be causing more harm than good, new findings say.

The research, published Thursday in JAMA Oncology, found that people who received chemotherapy to treat 22 of the 23 solid experienced between a 1.5 fold to 10 fold increase in risk of developing therapy-related myelodysplastic syndrome/acute myeloid leukemia, or tMDS/AML.

"Certain types of chemotherapy are known to elevate risk for acute myeloid leukemia/myelodysplastic syndrome, including alkylating agents, platinum compounds and topoisomerase II inhibitors," Dr. Lindsay Morton, lead author of the study and a senior investigator in the National Cancer Institute's Division of Cancer Epidemiology and Genetics, told UPI. "These agents are thought to elevate risk for blood cancers because they cause direct damage to the DNA in blood cells, but the exact mechanism is still under investigation."

Because incidents of the disease are so sparse, past studies of tMDS/AML included small sample sizes that produced scant data.

For this study, researchers examined data from more than 700,000 people between ages 20 and 84 diagnosed with solid tumors who survived at least one year after receiving initial chemotherapy between 2000 and 2013.

More than 1,600 of these people developed therapy-related myelodysplastic syndrome/acute myeloid leukemia, or tMDS/AML, a rare but fatal blood cancer.

Throughout the study period, the number of patients treated with platinum-based chemotherapy agents rose sharply, from 57 percent of patients between 2000 and 2001 to 81 percent between 2012 and 2013.

Platinum-based chemotherapy agents can increase risk of tMDS/AML, researchers say.

The Leukemia & Lymphoma Society expects that new leukemia, lymphoma and myeloma cases to make up 10 percent of approximately 1.7 million new cancer diagnoses by the end of this year.

Morton wanted to use her research to pinpoint more precisely the risk of developing tMDS/AML.

"Modern cancer therapy has resulted in improved survival for many people with cancer," Morton said. "The goal of our research was to quantify the risk of therapy-related acute myeloid leukemia/myelodysplastic syndrome, which occurs infrequently, in order to help balance these risks for patients treated in the modern era against potential gains in survival from chemotherapy."

The researchers hope the study can help limit the use dangerous of chemotherapy drugs and push for the development of safer solid cancer treatments in the future.

"Chemotherapy-related risks have been reported previously," Morton said. "For example, there have been detailed studies of platinum-based chemotherapy for testicular and ovarian cancer showing elevated risk for treatment-related leukemia."

"Continued efforts are needed to minimize exposure to cytotoxic chemotherapy without sacrificing efficacy. It is critical that we develop additional effective agents and cancer treatment approaches with fewer late sequelae," she added.