Primary lung cancer is the leading cause of cancer-related deaths globally, and approximately 50% had metastatic disease at the time of diagnosis. A rectal mass and unintended weight loss are common manifestations of rectal cancer. Our case presented with a rectal mass, but workup revealed a metastatic lesion from lung cancer. Lung cancer metastases to the lower gastrointestinal tract imply reduced survival compared with the already poor mean survival of stage IV lung cancer. Despite relevant therapy, the patient died 5 months after referral.