The chemo that’s eliminating a first cancer may cause another later; while targeting the DNA of cancer cells, the drugs also affect normal cells. Among the cells affected are the stem cells in bone marrow that go on to create red and white blood cells, making leukemia—blood cancer—a later risk.
According to the American Cancer Society, several types of chemotherapy have been linked to leukemia, usually two to ten years after initial treatment. Last December, Johns Hopkins researchers reported that about one in every 200 women—one half of one percent—receiving chemo for breast cancer develops leukemia within ten years. It’s a relatively small number, but it’s five times higher than women treated with surgery alone.
What you can do: Make sure the benefit of the chemotherapy you receive is worth the risk. Various genetic tests are helping doctors tailor treatments for individual patients. These tests aim to maximize the chance of a cure and avoid toxicity—including the risk of second cancers—whenever possible by treating only those most likely to benefit.
Sharon Hayden, 62, of Niuli’i, Hawaii, was able to avoid chemotherapy this way. When she developed stage 2 breast cancer in 2012, she was offered a test of gene activity in the tumor. The analysis revealed she had a low risk of recurrence and would receive little added benefit from chemo.
The test Hayden benefited from, called Oncotype DX, became available in 2004; since then, about 300,000 women have had their tumors analyzed. “In about 37 percent of the women, the results changed decisions about treatment, and there has been about a 20 percent decrease in the use of chemotherapy, usually in favor of hormonal treatment alone,” says Steven Shak, MD, chief medical officer at Genomic Health. The company has a similar test available for colon cancer, and tests for prostate, lung, and kidney cancers are in the works.