Patients are often surprised when they learn that cancer treatments such as radiation and chemotherapy may also cause cancer. Many chemotherapy drugs kill cancer cells by interfering with the synthesis of DNA. Since these drugs affect all cells, it is not surprising that they also affect the DNA of healthy cells. Consequently, these healthy cells may be slightly more likely to become leukemia cells if the patient survives his original cancer. Smart clinicians and patients can balance the likelihood of curing the current problem against the likelihood of future risks and design treatments that provide the maximum benefit with minimal risk.
Alkylating Agents
The Merck Manuals report that alkylating agents cause an increased risk of leukemia. Alkylating agents are a large class of chemotherapeutic drugs. The National Cancer Institute defines alkylating agents as drugs that interfere "with the cell's DNA and inhibit cancer cell growth." FamilyPracticeNotebook.com lists cyclophosphamide, mechlorethamine, chlorambucil, melphalan and cisplatin as akylating agents commonly used in cancer chemotherapy. Cyclophosphamide is also used to treat autoimmune diseases such as lupus and various diseases of the kidney.
Adriamycin
The website Chemocare.com reports that the chemotherapy drug adriamycin is associated with a slight risk of developing leukemia. According to the website, adriamycin is used to treat cancers of the "bladder, breast, head and neck, leukemia (some types), liver, lung, lymphomas, mesothelioma, multiple myeloma, neuroblastoma, ovary, pancreas, prostate, sarcomas, stomach, testis (germ cell), thyroid and uterus."
Research Issues
Measuring the relative risk posed by these drugs is difficult because they are often given in combination with other drugs. A 2005 paper published in the "Journal of Clinical Oncology" illustrates this problem. This study showed that 30 out of 9,796 patients treated with epirubicin and cyclophosphamide later presented with acute myeloid leukemia and myelodysplastic syndrome. Five other patients presented with other types of leukemia. Even if all types of leukemia are included, it appears that the relative risk is merely 0.35 percent.
Many of the leukemia patients in the study had taken drugs such as cisplatin, mitoxantrone and fluorouracil, which made it impossible to determine which drug caused the problem.
