Rectal Cancer Complicated by Acute Promyelocytic Leukemia

Globally colorectal cancer is one of the leading causes of mortality among men. Treatment modalities of chemotherapy and radiotherapy may put a risk in developing therapy related myeloid leukemia (TRML). TRML has been reported with Oxaliplatin, Capecitabine, and radiation therapy, which may consequently lead to DNA damage, causing a secondary disease. Acute Promyelocytic Leukemia (APL) is a type of TRML that occurs as a result of such therapies. We present a case of a 30 year old male who presented as a case of colorectal cancer. Subsequently, the patient received Capecitabine with radiotherapy followed by abdominoperineal resection. He received four additional cycles of XELOX protocol of chemotherapy. Months later, he returned with an intestinal obstruction and a picture of TRML. After a bone marrow biopsy, fluorescence in situ hybridization (FISH) and cytogenetics evaluation, the diagnosis of APL was confirmed. All-trans retinoic acid (ATRA) therapy was initiated with excellent response. In conclusion, TRML in the form of APL needs to be diagnosed early and treated as a medical emergency to prevent the high mortality rate associated with the disease.