Diagnosis and Treatment of Metastatic Colon Cancer in Pregnancy First Presenting as Multiple Liver Masses: A Case Report

Colorectal cancer (CRC) is the second most common cancer in women in Japan. However, it is uncommon during pregnancy. CRC diagnosis during pregnancy is often complicated and delayed due to the overlapping of symptoms, such as abdominal pain and nausea, with those of pregnancy and the limitations placed on potential diagnostic imaging and testing because of concerns for the fetus. A 39-year-old woman was referred from a local hospital at 32 weeks gestation after persistent right abdominal pain, which prompted an ultrasound that showed multiple liver lesions suggestive of malignancy. A combination of non-contrast computed tomography, non-contrast magnetic resonance imaging, contrast-enhanced ultrasound, and colonoscopy was utilized to make a definitive diagnosis; ultimately, colonoscopy confirmed the diagnosis of colon cancer with liver metastasis. A discussion within a multidisciplinary team led to the decision to deliver at 34 weeks by cesarean section and a left hemicolectomy was performed after delivery. The neonate was admitted to the neonatal intensive care unit due to prematurity but had no other complications. Chemotherapy was promptly initiated, and treatment was continued on an outpatient basis. Diagnostic algorithms for CRC during pregnancy are not yet well-established; however, the prognosis of CRC during pregnancy is poor, and clinicians should not hesitate to perform the necessary testing and consult experts in fields such as neonatology, medical oncology, internal medicine, and gastrointestinal surgery. Early diagnosis and intervention are essential for optimizing outcomes for both the mother and the fetus.