Colonic Metastasis of Lung Adenocarcinoma: A Case Report

Colonic metastases are extremely rare, regardless of primary lung cancer type. A 64-year-old female was referred to the hospital by her gastroenterologist after a same-day colonoscopy revealed a large rectosigmoid mass resulting in near total rectal occlusion. On admission, she complained of abdominal pain and constipation. She had a past medical history of non-small cell lung cancer (T1bN3M0 stage IIIB), diagnosed one year prior. She was thought to be in remission following radiation and immunotherapy with pembrolizumab. She underwent urgent surgical intervention and mass resection with tissue sampling. Pathology confirmed the diagnosis of metastatic lung adenocarcinoma. Systemic chemotherapy with pemetrexed and carboplatin followed by localized radiation to the pelvic region was administered. A refractory pelvic region tumor growth was evident on subsequent imaging. Cessation of chemoradiation therapy occurred after the patient experienced a debilitating stroke and she was transferred to hospice care. Colonic metastasis should be considered when patients with a history of primary lung cancer have abdominal symptoms.