Colorectal cancer resection is one of the most common types of abdominal surgery. Though most patients undergoing colorectal resection show recovery of bowel movements within a week, some have prolonged intestinal paralysis or postoperative ileus, resulting in decreasing patient comfort, increasing morbidity and mortality, a longer hospital stay and subsequent increased healthcare costs.

Prevention the incidence of postoperative ileus (POI) is quite important because of the negative clinical outcomes it causes. In the past two decades, many treatments and care approaches, such as fluid restriction, early enteral nutrition, and nonsteroidal anti-inflammatory drug are used for the management of POI. In theory of traditional Chinese medicine, oral simo decoction (SMD) or acupuncture at the tsusanli acupoint can boost gastrointestinal hypomotility. The efficacy of accelerating the return of gastrointestinal function by such single method or combination of them has been validated in randomized controlled trials and systematic review following several types of surgery. In recent years, chewing gum, a new and simple modality, has become a commonly applied method in order to prevent and reduce the POI. Systematic reviews and meta-analyses revealed that chewing gum provided significant benefits for the improvement of postoperative bowel function. More importantly, many official guidelines recommend chewing gum for an evidence-based approach in the prevention of POI. Despite these positive evidence, three newest randomized controlled trials are unable to demonstrate an effect of chewing gum on the recovery of bowel function after colorectal resection.

It is important to note that almost all previous randomized controlled trials are based on small sample size. This raises the question whether postoperative SMD, acupuncture at the tsusanli acupoint, or chewing gum can reduce risk of POI following colorectal resection among patients with large sample size. To examine this question, we conducted this randomized controlled trial to compare incidence of POI and length of hospital stay in colorectal cancer patients who received SMD and acupuncture, chewing gum or no intervention following resection.

Inclusion Criteria:

• Underwent open or laparoscopic colorectal cancer resection
• Diagnosis of colorectal cancer was confirmed by histopathological examination of surgical samples in all patients

Exclusion Criteria:

• Previously underwent exploratory laparotomy
• Known Central Nervous System tumors including metastatic brain disease
• History of organ allograft
• Substance abuse, medical, psychological or social conditions that may interfere with the patient's participation in the study or evaluation of the study results
• Any condition that is unstable or which could jeopardize the safety of the patient and his/her compliance in the study
• Pregnant or breast-feeding patients