chemotherapy
Credit: Rhoda Baer
The risk of developing myelodysplastic syndromes (MDS) or leukemias after treatment for early stage breast cancer is higher than previously reported, according to a study published in the Journal of Clinical Oncology.
Data from earlier studies showed that about 0.25% of breast cancer patients develop MDS or leukemia as a late effect of chemotherapy, said Judith Karp, MD, of the Johns Hopkins University School of Medicine in Baltimore, Maryland.
But Dr Karp and her colleagues found the 10-year incidence of MDS and leukemia among breast cancer patients to be about 0.5%.
“[T]he cumulative risk over a decade is now shown to be twice as high as we thought it was, and that risk doesn’t seem to slow down 5 years after treatment,” Dr Karp said. “Most medical oncologists have come to think that the risk is early and short-lived. So this was a little bit of a wake-up call that we are not seeing any plateau of that risk, and it is higher.”
Dr Karp and her colleagues reviewed data on 20,063 breast cancer patients treated at 8 US cancer centers between 1998 and 2007 whose cancer recurrence and secondary cancer rates were recorded in a database kept by the National Comprehensive Cancer Network.
At a median follow-up of 5.1 years, 50 patients had developed a marrow neoplasm, including acute myeloid leukemia (n=24), MDS/acute myeloid leukemia (n=15), chronic lymphocytic leukemia/small lymphocytic lymphoma (n=5), chronic myeloid leukemia (n=3), or acute lymphoblastic leukemia (n=3).
The risk of developing MDS/leukemia was about 7 times higher for patients who underwent surgery and received chemotherapy, compared to patients who did not receive chemotherapy. For patients who underwent surgery and received both chemotherapy and radiation, the risk was about 8 times higher.
The MDS/leukemia rates per 1000 person-years were 0.16 for surgery, 0.43 for surgery plus radiation, 0.46 for surgery plus chemotherapy, and 0.54 for all 3 modalities.
The cumulative incidence of MDS/leukemia doubled between years 5 and 10, rising from 0.24% to 0.48%. And only 9% of patients were alive at 10 years.
Antonio Wolff, MD, of the Johns Hopkins University School of Medicine, said this study could help early stage breast cancer patients and their physicians think more carefully about the use of preventive or adjuvant chemotherapy, especially when patients have a low risk of cancer recurrence.
“Our study provides useful information for physicians and patients to consider a potential downside of preventive or adjuvant chemotherapy in patients with very low risk of breast cancer recurrence,” he said.
“It could be a false and dangerous security blanket to some patients by exposing them to a small risk of serious late effects with little or no real benefit from the treatment.”
The researchers included a hypothetical case to put the risks of early stage breast cancer and its treatment in perspective. They described a 60-year-old woman in average health who was diagnosed with stage 1 breast cancer that was rapidly growing and estrogen receptor-positive.
The patient had an estimated 12.3% risk of dying of breast cancer after 10 years. She could improve her 10-year survival rate by 1.8% with 4 cycles of chemotherapy, but she would also increase her risk of MDS/leukemia over that same time by 0.5%.
Dr Wolff noted that it’s unclear whether the increased risk of MDS/leukemia after postsurgical chemotherapy applies to patients with other kinds of solid tumors, as the drug regimens used in breast cancer differ from those used for other cancers.
