The purpose of this study is to determine: (1) whether laparoscopy-assisted nerve-preserved total mesorectal excision (LNTME) is as safe as open TME for rectal cancer, and (2) whether LNTME is more effective for protection of pelvic autonomic nerve function from surgical impairing when comparing to open TME.

Inclusion Criteria:

1. Male patients
2. From 18 years old to 60 years old
3. Normal sexual function
4. Tumor located in rectum (defined as 5- to 12-cm from the anal verge)
5. Pathological confirmed rectal cancer
6. Preoperative T stage ranging from T1 to T4a according to the 7th Edition of AJCC Cancer Staging Manual
7. Tumor size < 5 cm
8. ASA score was I-II
9. Informed consent was written

Exclusion Criteria:

1. Distant cancer metastasis
2. History of abdominal surgery
3. With other type of malignancy
4. Preoperative voiding dysfunction
5. Preoperative sexual dysfunction
6. Refusing to attend this trial