摘要Multiple primary cancers refer to the condition where more than two cancers occur independently in an individual. The incidence of lung cancer in cases of colorectal cancer is rare and synchronous rectal cancer and lung cancer is even rare. A 61-year-old man was referred to our hospital with a 2-month history of blood in his stool, tenesmus, and mucous discharge in July 2010. Colonoscopy showed an irregular ulcerated rectal mass and histological examination of biopsy material showed a poorly differentiated adenocarcinoma. Computed tomography (CT) scan of the chest and abdomen showed a mass in the posterior segment of the right upper lobe of the lung and a mass in the right rectal wall of upper rectum. The rectal tumor was diagnosed as primary cancer based on the findings of immunohistochemical stain. An anterior resection (AR) and video assisted thoracoscopic (VAT) wedge resection were performed and histological findings of resected rectal and lung tumor specimen showed synchronous primary rectal cancer and lung cancer. A combination chemotherapy regimen with docetaxel and lobaplatin was used and the patient was successfully discharged from hospital in August 2010. Although the incidence of synchronous multiple primary cancers is very low, we need to remain suspicious, when faced with two or even multiple organ lesions, and employ the necessary examination methods to confirm the diagnosis. For synchronous multiple primary cancers, if conditions allow, surgical resection for all the cancers can be performed in a single operation.