Research led by Osaka International Cancer Institute in Japan shows that rates of therapy-related acute myeloid leukemia, linked to treatment for an earlier cancer, are going up as the overall number of cancer survivors increases.
As reported in the journal Cancer, the researchers showed the rates of treatment-related acute myeloid leukemia (AML) almost tripled between 1990 and 2020. The share of overall AML cases taken up by these patients has also increased from 4.4% to 8.2% over a similar time period.
With increasing numbers of cancer survivors in the U.S. and elsewhere, understanding the adverse effects of cancer treatment is becoming increasingly more important. Therapy‑related AML is a rare but serious complication of cytotoxic chemotherapy, and different chemotherapy drugs carry different levels of leukemia risk. Radiotherapy can also lead to this condition, but the risk is considered lower than that of chemotherapy.
“Several population‐based studies have analyzed the long‐term trend of therapy-related AML incidence, and the results are controversial,” write lead author Kenji Kishimoto, MD, PhD, a researcher at the Osaka International Cancer Institute, and colleagues.
“A national population‐based study did not demonstrate an increase in the incidence of therapy-related AML in Denmark between 2000 and 2013. In contrast, a significant increase in therapy-related AML incidence between 1997 and 2015 was identified in a Swedish nationwide study.”
As few such studies have been carried out in Asia, Kishimoto and colleagues analyzed how such rates have changed over time and whether the initial cancers leading to therapy-related AML have changed in Japan.
The researchers identified 9841 patients with AML in the Osaka Cancer Registry, 636 (6.5%) of whom had therapy-related AML. These patients were older when diagnosed than other AML patients at a median of 69 versus 66 years. There were also slightly more women with therapy-related AML than standard AML at 45% versus 40%. The time lag between first cancer and resultant AML was between two and 11 years (median five years).
In 1990, the incidence of therapy related AML was 0.13 per 100,000 people, but this had increased to 0.36 per 100,000 people by 2020. The share of all AML cases made up by therapy-related cases almost doubled from 4.4% in 1990 to 8.2% after 2010.
The most common earlier cancers before therapy-related AML were blood cancers (23%), breast cancer (15%), colorectal cancer (12%), and gastric cancer (9%). The mix shifted over time and gastric cancer became less common as the first cancer, while breast, head‑and‑neck, and lung cancers became more prominent.
“The study provides an important step towards better understanding how the nature of therapy-related AML is changing with the increasing number of cancer survivors,” said Kishimoto in a press release.
“Findings from this study lay the foundation for further studies to elucidate the mechanism of the change in therapy-related AML epidemiology,” add the authors.
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