Chronic myelogenous leukemia secondary to colon cancer: A case report

Colon cancer is a common malignancy of the digestive tract. An estimated 1148515 new cases of colon cancer were reported in 2020 worldwide. Chronic myeloid leukemia (CML) is a malignant tumor formed by the clonal proliferation of bone marrow hematopoietic stem cells, with an annual incidence rate of 1-2 cases per 100000 people worldwide. Leukemia can be secondary to solid tumors, and vice versa. Reports on CML secondary malignant tumors account for 8.7% but CML secondary to malignancy is extremely rare. Therapy-related CML is a rare but potentially fatal adverse event of chemotherapy or radiotherapy. Herein, we report a case of CML with colon cancer and discuss this unique patient population. Our findings can provide effective raw data and guidance for the diagnosis of this clinical disease.

A 61-year-old male patient attended our hospital due to leukocytosis for 5 days. In February 2020, the patient was diagnosed with colon cancer and underwent radical surgery and conventional chemotherapy with a stable condition. He was diagnosis was CML-chronic phase (Sokal score of 0.72) after examination. He was treated with imatinib (400 mg daily). When his conditions improved, the patient was discharged from our hospital and visited the outpatient department for follow-up twice a month.

CML in patients with colon cancer is extremely rare. Secondary hematological tumors may be multifactorial, and the exact mechanism is currently unknown. Owing to the slow progression of the disease, patients with CML show no symptoms in the early stage. However, with disease progression, obvious but non-specific symptoms may appear, including fever, anemia, bleeding tendency, and hypertrophy. Therefore, complete blood count monitoring for routine examination is recommended after cancer treatment for early detection of occult hematological tumors.