What happened, in summary

A 62-year-old woman underwent anterior rectal resection in 2009 for an upper rectal cancer. Chest and abdominal CT imaging at that time showed no distant metastases, and she received no further treatment after the operation. She remained without symptoms for several years. In November 2015, general fatigue, anal discharge and bleeding, abdominal distension, anemia and weight loss led to renewed evaluation. Examination showed a large tumor visible at the anus and perineal skin. Chest and abdominal CT again excluded lung, liver and other distant metastases, but showed extensive local growth through the perineal region. The tumor involved the levator ani and was closely adherent to the posterior bladder, uterus, vagina and perineal skin. Because the mass caused perianal obstruction, a left colostomy was performed to restore bowel passage. Her postoperative recovery was satisfactory without severe complications. She then received 6 cycles of mFOLFOX6 chemotherapy followed by radiotherapy to 40 Gy. Pathology showed invasive rectal adenocarcinoma with numerous malignant glands extending into the perirectal fat and reaching the serosal surface. The recurrence pattern was unusual because the disease had become very extensive locally around the perineum while repeated imaging still did not show distant metastatic spread.