This research plans to collect rectal cancer patients after sphincter-preserving surgery from 14 institutions in China mainland, observe the incidence and risk factors about bowel dysfunction after operation.

Inclusion Criteria:

1. Age ≥ 18 years
2. Adenocarcinoma confirmed by pathology
3. Distance from the lowest margin of tumor to the anal verge is ≤ 12cm, confirmed by hard sigmoidoscope.
4. The tumor is estimated to be resectable and confirmed by multidisciplinary team (MDT).
5. The operation is estimated to be sphincter-preserving.
6. The Eastern Cooperative Oncology Group(ECOG) performance status score of patient is ≤ 2.
7. The estimated life time is not less than one year.
8. The patient agree to sign the informed consent.

Exclusion Criteria:

1. The patient refuse to follow research plan.
2. Emergency case
3. Pregnant and lactating female patient
4. The patient did not accept radical resection.
5. The patient did not accept first stage resection and anastomosis.
6. The patient has experienced anal-rectal surgery.
7. The patient has experienced left colon surgery.
8. The patient suffered long-existing bowel dysfunction before rectal cancer diagnosis.
9. The patient was diagnosed with cognitive or communicative obstacles.
10. The patient was diagnosed with serious repeated infection or other concomitance diseases.
11. The patient has participated other medical research which may affect his/her bowel function.

Rectal cancer patients who accept sphincter-preserving surgery