Colorectal cancer (CRC) is one of the most common malignant tumors. The probability of suffering from colorectal cancer in a person’s life is 6 %. There are about 1.20 million new colorectal cancer cases in the world each year. Nearly 600,000 people die of colorectal cancer each year. Among all malignant tumors, both incidence and mortality of colorectal cancer are in the third position. In recent years, incidence and mortality of colorectal cancer in western-developed countries have decreased a little, whereas incidence of colorectal cancer in developing countries has still showed a rising trend [1].

Among all malignant tumors, incidence and mortality of colorectal cancer are in the third and fifth position, respectively, with a slight difference in different regions. In 2000, there were about 150,000 new colorectal cancer cases in our country, and nearly 80,000 patients died of colorectal cancer, and it showed a rising trend [2]. Over the past 20 years, epidemiological trend of colorectal cancer in our country has changed and showed some new characteristics: (1) Colorectal cancer showed a trend from low to high incidence. As the population base of our country is great, the absolute number of cases suffering from colorectal cancer and cases that die of colorectal cancer have surpassed that in the United States in recent years. (2) Rising trend of incidence of colon cancer is more significant than that of rectal cancer. (3) Low rectal cancer accounts for a high proportion, and early-stage colorectal cancer accounts for a low proportion. (4) Young people (<30 years old) account for a high proportion; average age of rectal cancer cases shows a trend of approaching to the level in developed countries [3].

Radical surgical resection is the only opportunity to cure colorectal cancer confined in the intestinal wall. Therefore, it has 80 % of the opportunity to cure colorectal cancer still confined in the intestinal wall in definite diagnosis and nearly 90 % of 5-year survival rate after performing radical surgical resection. However, if there is lymph node metastasis, 5-year survival rate will decrease to 60 % or so [4]. In general, earlier stage of colorectal cancer leads to a higher survival rate, and natural prognosis study on colorectal cancer indicates that early discovery is the most important measure to reduce disease-related mortality.

As onset of colorectal cancer is not obvious, clinical manifestation lacks specificity. About 60 % of colorectal cancer cases have had lymph node metastasis or distant metastasis when diagnosed [5]. Therefore, overall prognosis of colorectal cancer is still not optimistic at present. Although pathogeny of colorectal cancer is not clear, there have already been many reports on pathogeny-related risk factors during the course of development in the order of “normal mucosa-adenoma-adenocarcinoma,” which provides the possibility of colorectal cancer screening and early diagnosis.

Zheng Shu et al. carried out colorectal cancer screening by adoption of fecal occult blood test (FOBT) combined with sequential screening scheme. Eight-year follow-up results show that case fatality rate of colorectal cancer of screening group is lower than that of control group by 14.7 %, of which that of rectal cancer is reduced by 31.2 %, which indicates that primary prevention may intervene in and prevent the occurrence of colorectal cancer and secondary prevention can still reduce case fatality rate after occurrence of tumor [6]. Data of US National Polyp Study demonstrate that adenoma canceration rate is directly proportional to age and size of adenoma. Resection of adenoma may significantly reduce incidence rate of colorectal cancer [7].

The present study indicates that hereditary colorectal cancer accounts for about 20 % of the total colorectal cancer. The most common hereditary colorectal cancer includes familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). The former relates to APC gene mutation, whose manifestation is more than 100 diffuse adenomatous polyps in the large intestine, or there is definite familial history or hyperplasia occurs in congenital retinal pigment epithelium although the number of polyps is less than 100, while the latter relates to mismatch repair gene (hMLH1, hMSH2, hPMS1, hPMS2, etc.) mutation, whose manifestation is familial aggregation, where tumors are mostly located at the right colon, and extra-colorectal tumors frequently occur. Therefore, mutation detection of the abovementioned genes may provide reference for early discovery of hereditary colorectal cancer [8].

Because of the living standard, hygiene and health consciousness, and technical reasons, even in relatively developed provinces and municipalities in our country, the large-scale survey system including endoscopy for colorectal cancer, as established in European- and American-developed countries, has not been established; early diagnosis rate of colorectal cancer is low in our country. Overall 5-year survival rate is not so satisfactory either. How to establish an effective and convenient survey system to provide intervention and prevention during the course of development in the order of “normal mucosa-adenoma-adenocarcinoma” or realize early diagnosis after tumor is formed, which is a topic that each of us – colorectal surgeons – must consider carefully.

Digital rectal examination (DRE), as a simple and important examination method, has great significance in early discovery of anal canal cancer and rectal cancer. As mentioned above, incidence of low rectal cancer is high in our country. About 75 % of rectal cancer may be touched when conducting digital rectal examination. Among the cases where diagnosis of rectal cancer is delayed, about 85 % do not receive digital rectal examination. In addition, DRE may help judge the site and size of rectal tumor and its relation with adjacent tissues, such as prostate, vagina, etc., and if there is pelvic-planted metastatic node of colon cancer, etc., and provide reference for making clinical decisions. Therefore, digital rectal examination has important significance in the diagnosis and treatment of rectal cancer. If a patient has symptoms such as there is blood in his stool or his defecation habit changes or his stool deforms, conventional digital rectal examination should be conducted.

Endoscopy includes proctoscopy, sigmoidoscopy, and colonoscopy. At present digital rectal examination and colon fiberscopy are the basic means to examine colorectal cancer. Electronic colon fiberscopy is widely used in clinical applications. Endoscopy can examine the total colon, can even examine the pathological changes in the terminal ileum, and may obtain pathological biopsy simultaneously to define the nature of pathological changes. What should be stressed is that when a great colorectal tumor is discovered by colonoscopy, making the intestinal cavity become too narrow to allow the colonoscope body to pass, endoscopy has been unable to examine the total large intestine mucosa before operation. So the intestinal canal that has been examined by preoperative colonoscope should be examined more carefully during operation. When necessary, intraoperative colonoscope may be used for further examination to avoid omission of missed diagnosis of simultaneous multiple primary carcinoma or other adenomas.

It is indubitable that endoscopy is sensitive to the diagnosis of colorectal cancer, whereas such examination method still has some limitation. For example, examination results are affected by examinator’s operation level. Study shows that about 13 % of 5–9 mm adenomas and 27 % of less than 5 mm adenomas are missed in diagnosis. Even if the size of tumor mass is greater than 1 cm, the rate of missed diagnosis still reaches nearly 6 % [9]. In addition, such examination may be affected by the blind spot of the endoscope and has such risks as perforation, bleeding, or even death. Despite this, no other examination method can replace the important role of endoscopy in the diagnosis of colorectal cancer at present.

Basic principles of colorectal cancer operation are to (1) pay attention to “no-touch isolation technique,” (2) appropriate intestinal segment resection, and (3) normative lymphadenectomy. As for simultaneous multiple primary carcinoma, surgical resection should be strictly subject to colorectal cancer operation principles, respectively.

Eastern and western scholars always have dispute on whether or not conventional lateral pelvic lymphadenectomy (LPLD) should be performed for rectal cancer. Most Japanese scholars believe that lateral lymph node metastasis rate is between 14 and 29 %. Lateral lymphadenectomy may result in reduction of postoperative local recurrence rate by nearly 50 % and increase in 5-year survival rate by about 10 %. Therefore, conventional lateral pelvic lymphadenectomy is recommended. Japanese scholars proposed extended radical resection for rectal cancer by dissection of Clearance A, B, and C of the peripheral connective tissues of the rectum, of which A is the tissue resected by the aforesaid TME, B is the inside dissection of the internal iliac artery of the lateral lymph node, and C is the outside dissection of the internal iliac artery of the lateral lymph node, including obturator lymphadenectomy. Takahashi analyzed 764 rectal cancer cases that received the abovementioned three-clearance dissection, of which lateral lymph node metastasis occurred in 66 cases; cases with lateral lymph node metastasis account for 8.6 % of all rectal cancer cases and account for 16.4 % of low rectal cancer cases (less than 5 cm above dentate line). Therefore, the author’s opinion is that rectal cancer patients should receive extended dissection [28]. Domestic study carried out by Dong Xinshu et al. showed that among 782 cases of rectal cancer patients, lateral lymph node metastasis occurred in 64 cases; cases with lateral lymph node metastasis account for 8.2 % of all rectal cancer cases, of which lateral lymph node metastasis rate of rectal cancer below the peritoneal reflection is 12.5 %, while lateral lymph node metastasis rate of rectal cancer above the peritoneal reflection is 1.3 %. Based on this, the author thinks that upper metastasis and lateral metastasis are different paths. As for the rectal cancer below the peritoneal reflection, conventional lymphadenectomy should be performed [29]. But Grinnell in the United States reported that positive rate of the lateral lymph node is only 1.9 %. In addition, the author thinks that lateral lymph node metastasis should belong to distant metastasis; dissection has no clinical significance. Therefore, lateral pelvic lymphadenectomy is not recommended [30]. Why the study results between eastern and western scholars are so different? Yano et al. recently studied and compared many years of literature of both parties to the dispute and think that difference in the results of both parties is likely caused by different rectal cancer staging concept between east and west. If staging standard of rectal cancer is unified, lateral lymph node metastasis of low rectal cancer perhaps may result in similar positive rate in Japan and western countries [31].

As range of lateral lymphadenectomy is big, incidence rate of postoperative micturition and sexual dysfunction caused by intraoperative damage to the pelvic autonomic nerve also increases. For this reason, some scholars proposed extended radical resection of PANP, called as “functional extended radical resection.” After performing this operation, 62.3 % and 57.1 % of the patients can maintain normal erectile and sexual functions, respectively, and postoperative 5-year survival rate is 61.2 % [32]. However, Wan Yuanlian et al. also reported that lateral dissection may reduce pelvic recurrence from 17.7 % by adoption of traditional radical resection to 5.6 %, but there is no significant improvement of 5-year survival rate. Further analysis was conducted on the cases that had lateral lymph node metastasis and received radical resection and lateral dissection. Recurrence still occurred in 80 % of the patients within 2 years after operation; distant metastasis occurred in 75 % of the patients, and 3- and 5-year survival rate after operation was only 16.7 % and 0, which indicates that as lateral metastasis breaks through the barrier of fascia propria, it is not only local pathological change in the pelvic cavity, but also belongs to a part of pathological change of the whole body. Lateral dissection can reduce local recurrence rate, but cannot significantly improve survival rate [33, 34].

From the above analysis, although rectal cancer lateral lymphadenectomy can reduce postoperative local recurrence rate, great dispute still exists on the significance of dissection. Lymphatic diversion path and rule of middle and low rectal cancer need further illustration. Whether or not biological behaviors of lateral lymph node metastasis belong to a part of systemic metastasis requires further study and demonstration, and whether or not conventional lateral lymphadenectomy should be conducted for rectal cancer below the peritoneal reflection needs validation through multicenter randomized clinical trial on a large size of samples.

In 1991, Jacobs M reported laparoscopic radical resection of colorectal cancer for the first time. Through nearly 20 years of development, laparoscopic radical resection of colorectal cancer has achieved great development. Laparoscopic radical resection of colorectal cancer should observe all basic principles for open operation. As range of surgical resection is big, operative gap is small, and field of vision is often disturbed by the small intestine, there is some difficulty to perform such operation. Along with the accumulation of experience and development of advanced devices, laparoscopic-assisted resection of colorectal cancer increasingly becomes mature, and its safety and effectiveness are also recognized by many scholars both at home and abroad.