The promises and potential pitfalls of organ preservation for locally advanced rectal cancer. Surgical Oncology

摘要

Two steps ahead, you are a leader; 10 steps ahead, you are a target. I wonder which Norm Nigro felt like when he first argued that abdominoperineal resection should be used only as a salvage operation for anal cancer > 30 years ago. Because of his efforts, organ preservation became the standard for anal cancer without a randomized trial. What is different about rectal cancer? Several things. Most importantly, the intrinsic radiosensitivity is dramatically different. Durable complete responses to chemoradiation combinations for anal cancer vary from 60% to 90%, depending on patient selection, the radiation dose, and possibly the chemotherapeutic agents that are used,2'3 compared with pathologic complete response rates that usually range from 10% to 20% with neo-adjuvant chemoradiation in rectal tumors. Second, differences in anatomical location and tumor biology contribute to higher salvage rates for recurrent anal cancer than for rectal cancer. Anal cancer recurrences produce symptoms (tumor mass, analcanal pain, or bleeding) early and are accessible for physical examination, resulting in detection most often when they are localized and resectable. In contrast, recurrent rectal cancer is a devastating problem with frequent infiltration of the sacrum, low resectability, low 5-year overall survival rates, and significant morbidity even when resected. Biologically, anal cancers also tend to remain locoregionally confined much longer than rectal cancers. The greater tendency of rectal tumors to metastasize makes giving them a second chance to do so undesirable. Therefore, the intrinsic radiosensitivity, resectability rates, and propensity for distant metastasis distinguish anal and rectal cancers.