[Techniques and classification of intersphincteric resection for ultra-low rectal cancer].

ISR is the most widely used anal-preserving operation for ultra-low rectal cancer. It can be divided into total ISR, subtotal ISR and partial ISR according to the resection range of internal sphincter. The advantage of ISR is that it can preserve the sphincter while ensuring the safety of oncology for ultra-low rectal cancer, representing the state of the art. However, it still needs to face the problem that the quality of life will decline due to poor postoperative anal function. The conformal sphincter-preserving operation (CSPO) is a functional anal-preserving surgery improved on the basis of ISR. It is superior to ISR in the postoperative anal function and patients' quality of life. So it can be a new choice for ultra-low rectal cancer.