Cancer Risks of Cancer Treatment

Leukemia risk related to cancer treatments

(RxWiki News) You do what you can – what you’re told – to beat the cancer. Chemotherapy is recommended and it works. Years later, though, you’re diagnosed with a blood cancer that could be related to the chemotherapy. Is this really happening?

A recent study has identified certain chemotherapy agents used for some cancers that may increase a cancer patient’s risk of developing leukemia later. Therapy-related acute myeloid leukemia (tAML) is a rare but often fatal condition.

Researchers delved into this unfortunate consequence of cancer treatment and pinpointed which chemotherapies resulted in the greatest risks.

This information may help physicians design therapies that minimize these serious risks.

"Ask about the long-term risks associated with all cancer treatments."

Lindsay Morton, PhD, of the National Cancer Institute (NCI), was the lead author of this study that examined data on hundreds of thousands of cancer patients.

"In the course of improving interventions and survival rates in many types of cancer, we have learned that certain chemotherapies can cause damage to cells in the bone marrow, increasing a patient's risk of leukemia. However, no recent large-scale studies have evaluated how the risk of treatment-related leukemia has evolved with the changing treatment strategies," Dr. Morton said in a statement.

Dr. Morton’s team of researchers from the NCI's Division of Cancer Epidemiology and Genetics used data from cancer registries in the US Surveillance, Epidemiology, and End Results (SEER) Program to identify 426,068 patients who had been treated for cancer with chemotherapy.

To determine overall tAML risk, the scientists evaluated the type of cancer, how old the person was when diagnosed, year of diagnosis and amount of time that had passed since diagnosis.

A total of 801 patients with tAML were identified – a number which is five times higher than the number of cases expected to occur in the general population. About 14,500 Americans are diagnosed with AML every year.

The data did not name the type or dosing of chemotherapy used, so the researchers relied on accepted practices at the time of treatment. Changes in treatment recommendations and new discoveries were considered.

One trend became obvious early on. More patients received chemotherapy to treat many malignancies – with or without radiation – during the study period.

Here’s what the analysis uncovered:

  • Individuals treated for non-Hodgkin lymphoma (NHL) had an increased risk of tAML, a trend that’s been seen over the past several decades. This may have been due to the multiple courses of chemotherapy given to NHL patients, which has improved survival.
  • Researchers identified an increased risk of tAML for patients who underwent chemotherapy since 2000 to treat anal, cervical, esophageal and prostate cancer.
  • Patients treated since the 1990s for bone, joint and endometrial cancers were also at higher tAML risk.
  • Myeloma patients had the highest risk of tAML, which may have been linked to the common use of melphalan (trade name Alkeran) - a medication previous studies have associated with higher leukemia risks.
  • tAML risks for breast cancer patients have been decreasing since the 1980s, which may be due to an increased use of cyclophosphamide-based chemotherapy (trade names Cytoxan, Neosar, among others).  
  • Declines were also seen in ovarian cancer patients, probably because of a switch from melphalan, to platinum-based chemotherapy.
  • After 10 years, patients treated for non-blood cancers no longer had higher tAML risks.
  • tAML risks persisted beyond 10 years for people treated for NHL, Hodgkin's lymphoma and myeloma.

"Future studies should identify patients at the highest risk of tAML so that the risks can be weighed against the benefits of chemotherapy, particularly for cancers with favorable long-term survival," said Dr. Morton.

She added, "Further research is also warranted to assess the risks associated with new targeted and immunomodulatory agents by including secondary malignancies such as tAML as endpoints in prospective clinical studies of new agents or new uses of standard agents."

This study was published February 13 in the journal Blood. The research was supported by Intramural Program of the National Cancer Institute, National Institutes of Health. No conflicts of interest were reported.

Review Date: 
February 14, 2013