Nested case-control study on the risk factors of colorectal cancer

Colorectal cancer in the Linxian China Nutrition Intervention Trial: Risk factors and intervention results

BACKGROUND

Colorectal cancer (CRC) is among the most common cancers in economically developed countries and developing world. While dietary factors are associated with risk of CRC in the West and urban China, little is known about risk or protective factors in rural China.

METHODS

The Linxian General Population Nutrition Intervention Trial (NIT) cohort was established over 30 years ago to test whether daily multivitamin/mineral supplements could reduce the incidence and mortality of esophageal/gastric cardia cancer. The cohort included a total of 29,553 healthy participants 40-69 years old who were randomly assigned to supplements or placebos via a 24 fractional factorial study design. We examined risk factors for the development of CRC as well as the effects of four different nutritional factors (Factor A: retinol, zinc; B: riboflavin, niacin; C: ascorbic acid, molybdenum; D: selenium, alpha-tocopherol, beta-carotene,) on CRC incidence following 5.25 years of supplementation in this randomized, placebo-controlled intervention trial.

RESULTS

CRC risk increased with age and height as well as piped water usage, family history of CRC, and consumption of foods cooked in oil, eggs, and fresh fruits. No effect on CRC was seen for any of these four intervention factors tested in both genders, but CRC was reduced 37% in females who received Factor D (selenium/alpha-tocopherol/beta-carotene) (RR = 0.63, 95% CI = 0.43-0.92, P = 0.016) compared to females who did not receive Factor D.

CONCLUSIONS

In this undernourished rural Chinese population, CRC risk factors in this Chinese cohort showed both similarities and differences compared to Western and urban Asian Chinese populations. Intervention results suggested a potential benefit for women supplemented with selenium/alpha-tocopherol/beta-carotene.

Validity of an observational assessment tool for multifaceted evaluation of faecal condition

Faecal volume, form, colour, and odour are associated with various diseases, dietary habits, and the gut microbiome. Multifaceted assessment of faecal condition will be needed for future research and practice. Faecal observation has advantages, as it is non-invasive, frequent, and easy. We have developed and validated an illustrative card tool for comprehensively faecal assessment. In 38 healthy adults, observations of volume, form, colour, and odour of faeces using the tool were compared to the objective characteristics of the actual faeces determined using a weighing scale, moisture meter, hardness meter, colourimeter, and odour measuring device. A significant positive correlation (ρ = 0.778) was observed between the number of faecal model (2 cm × 10 cm) units and the actual weight. The Bristol Stool Form Scale showed a significant positive correlation with the moisture content (ρ = 0.717) and negative correlations with faecal hardness (ρ = −0.843) and adhesiveness (ρ = −0.761). The L*a*b* colour space values of the stool differed significantly among observational judgments using the colour card tool. No significant correlation was observed between the observation of odour and the measured odour index. In conclusion, the faecal volume, form, and colour can be estimated by observation using the multifaceted assessment card tool.

Characteristics and comparison of colorectal cancer incidence in Beijing with other regions in the world

Background

Population-based epidemiologic studies about colorectal cancer are lacking in China. This study aims to provide a basis for colorectal cancer screening and prevention, through analysis and comparisons the characteristics of the trends in colorectal cancer incidence in Beijing and selected representative regions.

RESULTS

The annual incidence rate in Beijing region increased significantly, from 9.40/100,000 in 1998 to 18.61/100,000 in 2012. The stratified rate showed that the incidence of distal colon adenocarcinoma increased substantially in men, especially in those aged > 75 years and residing in urban areas. Although the incidence rate in Beijing is still lower than in Shanghai, Jiashan, and Hong Kong in China, it is increasing rapidly. Further, the incidence rate in Beijing is lower than in New York, Oxford and Osaka, but higher than in Mumbai and Kyadondo. The incidence trend in Beijing is increasing especially in older groups, while in other regions such as New York, it is decreasing in these age groups.

Materials and Methods

Colorectal cancer incidence data were obtained from Beijing Cancer Registry and Cancer Incidence in Five Continents Plus database. All incidence rates were age-standardized according to Segi's world population. Incidence trends were characterized by calculating the annual percent changes using the Joinpoint Regression Program.

Conclusions

Compared with other regions, Beijing has a medium level of colorectal cancer incidence, however, it is increasing significantly. There are obvious differences in the cancer subsite, sex and age distributions between Beijing and other regions. Prevention and screening of colorectal cancer in Beijing should be strengthened.

Red Meat and Colorectal Cancer: A Quantitative Update on the State of the Epidemiologic Science

The potential relationship between red meat consumption and colorectal cancer (CRC) has been the subject of scientific debate. Given the high degree of resulting uncertainty, our objective was to update the state of the science by conducting a systematic quantitative assessment of the epidemiologic literature. Specifically, we updated and expanded our previous meta-analysis by integrating data from new prospective cohort studies and conducting a broader evaluation of the relative risk estimates by specific intake categories. Data from 27 independent prospective cohort studies were meta-analyzed using random-effects models, and sources of potential heterogeneity were examined through subgroup and sensitivity analyses. In addition, a comprehensive evaluation of potential dose-response patterns was conducted. In the meta-analysis of all cohorts, a weakly elevated summary relative risk was observed (1.11, 95% CI: 1.03-1.19); however, statistically significant heterogeneity was present. In general, summary associations were attenuated (closer to the null and less heterogeneous) in models that isolated fresh red meat (from processed meat), adjusted for more relevant factors, analyzed women only, and were conducted in countries outside of the United States. Furthermore, no clear patterns of dose-response were apparent. In conclusion, the state of the epidemiologic science on red meat consumption and CRC is best described in terms of weak associations, heterogeneity, an inability to disentangle effects from other dietary and lifestyle factors, lack of a clear dose-response effect, and weakening evidence over time. KEY TEACHING POINTS: •The role of red meat consumption in colorectal cancer risk has been widely contested among the scientific community.•In the current meta-analysis of red meat intake and colorectal cancer, we comprehensively examined associations by creating numerous sub-group stratifications, conducting extensive sensitivity analyses, and evaluating dose-response using several different methods.•Overall, all summary associations were weak in magnitude with no clear dose-response patterns.•Interpretation of findings from epidemiologic studies investigating diet and health outcomes involves numerous methodological considerations, such as accurately measuring food intake, dietary pattern differences across populations, food definitions, outcome classifications, bias and confounding, multicollinearity, biological mechanisms, genetic variation in metabolizing enzymes, and differences in analytical metrics and statistical testing parameters.

Performance of a colorectal cancer screening protocol in an economically and medically underserved population

The performance of combining fecal immunochemical tests (FITs) and a high-risk factor questionnaire (HRFQ) in colorectal cancer (CRC) screening in economically and medically underserved populations is uncertain. This study investigated the performance of a CRC screening protocol of combining FITs and an HRFQ as primary screening methods in a rural Chinese population. A CRC mass screening was conducted using FITs and an HRFQ as the first and colonoscopy as the second stage of screening in Jiashan, 2007-2009. The target population was 31,963 residents in three communities. The compliance was 84.7% for HRFQ, 76.4% for FITs, and 78.7% for colonoscopy. The detected rates of cancer, adenoma, nonadenomatous polyps, and advanced neoplasm were 2.7%, 14.8%, 5.9%, and 8.9% by FITs, which were higher than those by HRFQ (0.5%, 9.2%, 4.8%, and 3.8%, respectively). There was no significant difference in detected rate for nonadenomatous polyps between FITs and HRFQ. A total of 41.2% adenomas, 53.2% nonadenomatous polyps, and 29.8% advanced neoplasms were detected by HRFQ but missed by FITs. Positive predictive value of the screening protocol of combining FITs and HRFQ for advanced neoplasm was 5.7%, which was higher than FITs alone. Men had a higher prevalence of advanced neoplasm than women. Results indicate that combining FITs and HRFQ as primary screening methods is an efficient CRC screening strategy in economically and medically underserved populations.

Red and processed meat and colorectal cancer incidence: meta-analysis of prospective studies

BACKGROUND

The evidence that red and processed meat influences colorectal carcinogenesis was judged convincing in the 2007 World Cancer Research Fund/American Institute of Cancer Research report. Since then, ten prospective studies have published new results. Here we update the evidence from prospective studies and explore whether there is a non-linear association of red and processed meats with colorectal cancer risk.

METHODS AND FINDINGS

Relevant prospective studies were identified in PubMed until March 2011. For each study, relative risks and 95% confidence intervals (CI) were extracted and pooled with a random-effects model, weighting for the inverse of the variance, in highest versus lowest intake comparison, and dose-response meta-analyses. Red and processed meats intake was associated with increased colorectal cancer risk. The summary relative risk (RR) of colorectal cancer for the highest versus the lowest intake was 1.22 (95% CI  =  1.11-1.34) and the RR for every 100 g/day increase was 1.14 (95% CI  =  1.04-1.24). Non-linear dose-response meta-analyses revealed that colorectal cancer risk increases approximately linearly with increasing intake of red and processed meats up to approximately 140 g/day, where the curve approaches its plateau. The associations were similar for colon and rectal cancer risk. When analyzed separately, colorectal cancer risk was related to intake of fresh red meat (RR(for 100 g/day increase)  =  1.17, 95% CI  =  1.05-1.31) and processed meat (RR (for 50 g/day increase)  =  1.18, 95% CI  =  1.10-1.28). Similar results were observed for colon cancer, but for rectal cancer, no significant associations were observed.

CONCLUSIONS

High intake of red and processed meat is associated with significant increased risk of colorectal, colon and rectal cancers. The overall evidence of prospective studies supports limiting red and processed meat consumption as one of the dietary recommendations for the prevention of colorectal cancer.

Red meat and colorectal cancer: a critical summary of prospective epidemiologic studies

Meat consumption and cancer has been evaluated in hundreds of epidemiologic studies over the past three decades; however, the possible role of this food group on carcinogenesis is equivocal. In this comprehensive review, the currently available epidemiologic prospective studies of red meat intake and colorectal cancer are summarized to provide a greater understanding of any potential relationships. Specifically, salient demographic, methodological and analytical information is synthesized across 35 prospective studies. Collectively, associations between red meat consumption and colorectal cancer are generally weak in magnitude, with most relative risks below 1.50 and not statistically significant, and there is a lack of a clear dose-response trend. Results are variable by anatomic tumour site (colon vs. rectum) and by gender, as the epidemiologic data are not indicative of a positive association among women while most associations are weakly elevated among men. Colinearity between red meat intake and other dietary factors (e.g. Western lifestyle, high intake of refined sugars and alcohol, low intake of fruits, vegetables and fibre) and behavioural factors (e.g. low physical activity, high smoking prevalence, high body mass index) limit the ability to analytically isolate the independent effects of red meat consumption. Because of these factors, the currently available epidemiologic evidence is not sufficient to support an independent positive association between red meat consumption and colorectal cancer.

Genetic polymorphisms of the uridine diphosphate glucuronosyltransferase 1A7 and colorectal cancer risk in relation to cigarette smoking and alcohol drinking in a Chinese population

BACKGROUND

The impact of uridine diphosphate glucuronosyltransferase 1A7 (UGT1A7) polymorphisms on genetic susceptibility to digestive system cancer has received close attention since the discovery by Guillemette, the polymorphisms of which may alter enzyme activity. To clarify the allele frequency distribution and its association with risk of colorectal cancer, a population-based case-control study was carried out in Chinese population.

METHODS

A total of 140 patients with colorectal cancer and 280 cancer-free frequency-matched controls from a follow-up cohort population established in 1989, were enrolled. For the UGT1A7 polymorphisms analysis, polymerase chain reaction (PCR)-based genotyping techniques including semi-nested PCR, allele-specific PCR and PCR-restriction fragment length polymorphism (RFLP) were developed.

RESULTS

The variant allele frequencies in patients and controls were 50.0% and 38.6%, respectively, which were significantly associated with risk of colorectal cancer (odds ratio [OR]: 1.59; 95% confidence interval [CI]: 1.19-2.13). For the variant genotypes analysis, *2/*2 and *3/*3 exhibited a significant association with risk of colorectal cancer (OR: 7.80, 95%CI: 2.66-22.87; OR: 3.47, 95%CI: 1.51-7.97, respectively). Stratification analysis indicated that in previous-current cigarette smoking (cigarette smoking history), current cigarette smoking (current cigarette smoking status), previous-current alcohol drinking (alcohol drinking history) or current alcohol drinking individuals (current alcohol drinking status), the risk developing colorectal cancer increased: OR (95%CI), 2.81 (0.97-8.11), 3.39 (1.19-9.67), 2.89 (0.99-8.46) and 3.14 (1.09-9.09), respectively.

CONCLUSIONS

UGT1A7 polymorphisms may have a significant modifying effect on colorectal cancer risk, which may interact with environmental factors, cigarette smoking and alcohol drinking in colorectal carcinogenesis.

The association between drinking water source and colorectal cancer incidence in Jiashan County of China: a prospective cohort study

BACKGROUND

The pollution of drinking water, e.g. from rivers and pools, has long been recognized to be associated with an increased risk for colorectal cancer (CRC), but there are few direct prospective cohort studies related to person-years on the relative risks of different sources of drinking water for CRC, hence the reason for our study.

METHODS

Based on a screening for CRC among residents aged 30 years and over in Jiashan County, Zhejiang Province, China, a total of 64,115 residents were classified into five cohorts by their source of drinking water and followed-up from 1st May 1990 to 1st January 2001. Person-years was calculated for every cohort member and Poisson regression was used to control potential confounding variables including demographic variables and smoking history, and to attain crude and adjusted relative risks based on person-years.

RESULTS

A trend was seen toward increasing incidence rates for CRC from the drinking water sources of municipal, river, ditch, mixed water to well in turn as shown by relative risk rates of 29.61, 32.67, 33.45, 40.87 and 58.67 per 100,000 inhabitants. Only the role in risk of well water was significantly different from municipal water (P < 0.05). After the confounding variables were adjusted, the significant risk from well water could be seen for colon cancer, rectal cancer as well as CRC. The relative risks were 1.741 [95% confidence interval (CI) 1.001-3.029], 2.228 (95% CI 1.432-3.466) and 2.022 (95% CI 1.432-2.854), respectively.

CONCLUSION

Drinking well water over a long period was identified as playing a role in the risk for CRC, especially for rectal cancer.

Alcohol drinking and colorectal cancer: A population-based prospective cohort study in China

STUDY OBJECTIVE

To asses the association between alcohol consumption and the risk of colorectal cancer (CRC) in the Chinese population.

DESIGN

A population-based prospective cohort study was initiated from the colorectal cancer screening population in Jiashan County in 1989-1990. The drinking habits of individuals were investigated with demographic information.

SETTING

A cohort study was followed-up from 1st May 1990 to 1st January 2001 and censored at the date of diagnosis of CRC, at death from any causes, or at 1st January 2001, whichever came first, and the person-time was computed.

PARTICIPANTS

Two hundred and forty two CRC patients were diagnosed during the study period and 64,100 individuals finished the follow-up.

RESULTS

The distribution of sex, smoking status, occupation, education level and marital status were all significantly different among different drinking habits at baseline. When the above factors were adjusted, no significant association was observed between alcohol consumption and the risk of CRC. Exclusion of individuals diagnosed cancer less than 1 year after the examination date did not alter the strength of an alcohol-CRC relationship. Further analysis in sex strata also did not show a significant relationship.

CONCLUSIONS

Alcohol drinking may not be associated with a higher risk of CRC in the Chinese population.

Mutational spectra of p53 in geographically localized esophageal squamous cell carcinoma groups in China

BACKGROUND

Esophageal carcinoma is a particularly interesting tumor because of the dramatic difference in its incidence and geographic distribution among populations of similar ethnic origin. Epidemiologic data have suggested that many environmental exposures may be associated with an increased risk of its formation.

METHODS

In this study, 92 samples of esophageal squamous cell carcinoma (ESCC) were collected from patients who resided in 2 geographic areas in China with different incidences of ESCC: Linxian and Zhejiang. Overexpression and mutations of the p53 tumor-suppressor gene were examined by using immunohistochemistry, single-strand conformation polymorphism analysis, and direct sequencing.

RESULTS

The rates of point mutation and overexpression of p53 in the ESCC specimens studied were 30.4% (29 of 92 specimens) and 51.1% (47 of 92 specimens), respectively. The overexpression of p53 was associated with tumor metastasis and with 5-year case fatality. Significant differences were found in the rates of overexpression and mutations in patients with clinical T2 tumors between the specimens from Linxian, which is a high-incidence geographic area, and the specimens from Zhejiang, which is a low-incidence area. Furthermore, different mutational spectra were found in the tumor samples from these two geographic areas: In tumor samples from Linxian, the most common substitution mutation was a transversion in exon 5, whereas the most common mutations in tumor samples from Zhejiang were transitions in exon 7.

CONCLUSIONS

The data suggest that the mutation and overexpression of p53 may play important roles in the development of ESCC. The changes in p53 may reflect environmental exposure to the different combinations of mutagenic factors and genetic instability demonstrated by the populations in Linxian and Zhejiang. The overexpression of p53 protein may have significance as a prognostic factor for patients with esophageal carcinoma.

Inhibitirve effect of caffeic acid phenethyl ester on proliferation of human colorectal cancer cell line HCT116

AIM: To study the effect of caffeic acid phenethyl ester (CAPE) on proliferation, cell cycle, apoptosis in the cultured colorectal cancer cell line HCT116.

METHODS: HCT116 cells were treated with CAPE at serial concentrations of 80, 40, 20, 10, 5, and 2.5 mg/L. The proliferative status of HCT116 cells was measured by using methabenzthiazuron (MTT) assay. Cell cycle was analyzed by using flow cytometry (FCM) with propidium iodide (PI) labeling method. The rate of apoptosis was detected by using FCM with Annexin V-FITC and PI double labeling method.

RESULTS: After HCT116 cells were exposed to CAPE (80, 40, 20, 10, 5 and 2.5 mg/L) for 24, 48, 72 and 96 h, CAPE displayed a strong growth inhibitory effect on HCT116 cells in a dose-and time-dependent manner. FCM analysis showed that G0 /G1 phase rate increased, S phase rate decreased and apoptosis rate increased after HCT116 cells were exposed to CAPE (10, 5, and 2.5 mg/L) for 24 h, which were positively related to the concentration of CAPE.

CONCLUSION: CAPE can inhibit the proliferation of human colorectal cancer cell line HCT116, which is related to the cell cycle arrest and apoptosis.

Relationship between VEGF-C expression and lymph node metastasis and prognosis in large intestinal carcinoma

AIM: To explore the expression of endothelial growth factors C (VEGF-C) in large intestine carcinoma, and its relationship to clinicopathological features and prognosis.

METHODS: The expression of VEGF-C in 96 cases of large intestine carcinoma was detected by SP immunohistochemical technique and its relationship to clinicopathological features and prognosis were analysed.

RESULTS: The expression of VEGF-C was significantly higher in intratumoral tissue than that in normal mucosa(42/96 vs 19/96, P < 0.01). VEGF-C positive expression was significantly correlated with tumor differentiation, Dukes' stage, lymph node metastasis and prognosis in 96 cases of large intestine carcinoma (P < 0.01 or P < 0.05), but its relationship to age and gender of patient, size, site and depth of invasion of tumour and organ metastasis was not found (P>0.05). The expression of VEGF-C in metastatic lymph nodes was fairly consistent with that in the primary tumour (P < 0.01).

CONCLUSION: The overexpression of VEGF-C in large intestine carcinoma can develop lymph node metastasis by inducing lymphangiogenesis, and it may serve as one prognostic factor and guide the treatment.

Anatomic pathology of tumor cell spread through lymph nodes in the mesorectum of rectal cancer

AIM: To investigate the size, distribution, and pattern of metastases and micrometastases of lymph nodes (LNs) within the mesorectum of rectal cancer.

METHODS: All rectal cancer specimens obtained by total mesorectal excision were treated with lymph node revealing solution to retrieve all LNs, which were detected with a combination use of haematoxylin and eosin staining and immunohistochemical (IHC) staining with an antibody against cytokeratin 20.

RESULTS: A total of 548 LNs in 31 specimens were harvested, with 17.7 nodes per case. 153 nodes (27.9%) in 27 patients (87.1%) were found positive by routine pathological examination and IHC staining. Of all the nodes retrieved, nodes <0.5 cm numbered 366 (66.8%) with 91 (59.5%) positive. Among the 27 metastasized cases, there were 15 cases whose tumors were located in the back wall of the rectum, in which 78 nodes were detected positive with 75 nodes along the superior rectal artery. In the other 12 cases with tumors positioned in the lateral wall, 75 nodes were diagnosed positive, with 37 nodes, 8 nodes around the branch of superior rectal artery and middle rectal artery on tumor side, and 9 nodes, 0 nodes on the opposite side, respectively.

CONCLUSION: The majority of tumor positive LNs in the mesorectum are <0.5 cm in diameter. LNs within the mesorectum are distributed mainly along major supplying vessels with around the superior rectal artery most. The pattern of lymphatic spread of rectal cancer has close relationships with tumor location in the rectal wall. Tumors in the posterior wall may spread in both sides of the mesorectum simultaneously, while tumors localized in one lateral wall tend to metastasize preferably to LNs in the mesorectum of tumor side.

Effect of diet, life style, and other environmental/chemopreventive factors on colorectal cancer development, and assessment of the risks

This review presents a comprehensive, evenhanded evaluation of the evidence from experimental, in vitro and human studies associating environmental and therapeutic factors with risk of colorectal cancer. Life styles correlated with the greatest increase in colorectal cancer risk are the ones that typify a diet rich in fat and calories, alcohol drinking and tobacco smoking, and low intake of vegetable, fruits and fibers, referred to as a "western diet," as well as sedentary style (i.e., no- or low-exercise). This kind of life style has also been associated with other chronic diseases (other cancers, obesity, dyslipedemia, diabetes, hypertension cardiovascular, and hypertension). The evidence does not implicated red meat as a risk factor, and fiber has been shown to protect against colorectal adenomas and carcinomas. Calcium, vitamin D, folate, and some antioxidant vitamins and minerals (gamma-tocopherol and selenium) have protective effects, and daily exercise for > or =30 min results in a significant decrease in risk. Estrogen use (hormone replacement therapy) substantially reduces colorectal cancer risk in postmenopausal women. Nonsteroidal anti-inflammatory drugs (e.g., aspirin) in excessive doses is protective, especially in high risk populations, but the side effects of its use and cost incurred due to its continued intake over long periods must be carefully scrutinized before any recommendations are made for the general public.

Comparative evaluation of immune response after laparoscopical and open total mesorectal excisions with anal sphincter preservation in patients with rectal cancer

AIM: The study of immune response of open versus laparoscopical total mesorectal excision with anal sphincter preservation in patients with rectal cancer has not been reported yet. The dissected retroperitoneal area that contacts directly with carbon dioxide is extensive in laparoscopic total mesorectal excision with anal sphincter preservation surgery. It is important to clarify whether the immune response of laparoscopic total mesorectal excision with anal sphincter preservation (LTME with ASP) in patients with rectal cancer is suppressed more severely than that of open surgery (OTME with ASP). This study was designed to compare the immune functions after laparoscopic and open total mesorectal excision with anal sphincter preservation for rectal cancer.

METHODS: This study involved 45 patients undergoing laparoscopic (n = 20) and open (n = 25) total mesorectal excisions with anal sphincter preservation for rectal cancer. Serum interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necrosis factor α (TNF_α) were assayed preoperatively and on days 1 and 5 postoperatively. CD3⁺ and CD56⁺ T lymphocyte count, CD3^- and CD56⁺ natural killer cell (NK) count and immunoglobulin (IgG/IgM/IgA) were assayed preoperatively and on day 5 postoperatively. The numbers of CD3⁺ and CD56⁺ T lymphocytes and CD3^- and CD56⁺ NK cells were counted using flow cytometry. An enzyme-linked immunosorbent assay (ELISA) was used for IL-2, IL-6 and TNF_α determination. And IgG, IgM, and IgA were assayed using immunonephelometry.

RESULTS: The demographic data of the two groups had no difference. The preoperative levels of CD3⁺ and CD56⁺ T lymphocyte count, CD3^- and CD56⁺ NK count, serum IgG, IgM, IgA, IL-2, IL-6 and TNF_α also had no significant difference in the two groups (P > 0.05). The CD3⁺ and CD56⁺ T lymphocyte counts had no obvious changes after surgery in laparoscopic (d = -0.79% ± 3.83%) and open (d = 0.42% ± 2.09%) groups. The CD3^- and CD56⁺ NK counts were decreased postoperatively in both laparoscopic (d = -7.23% ± 11.33%) and open (d = -9.21% ± 13.93%) groups. The differences of the determined values of serum IgG, IgM and IgA on the fifth day after operation subtracted those before operation were -2.56 ± 2.14 g/L, -252.35 ± 392.94 mg/L, -506.15 ± 912.24 mg/L in laparoscopic group, and -1.81 ± 2.10 g/L, -282.72 ± 356.75 mg/L, -252.20 ± 396.28 mg/L in open group, respectively. The levels of IL-2 were decreased after operation in both groups. However, the levels of IL-6 were decreased after laparoscopic surgery (d₁ = -23.14 ± 263.97 ng/L and d₅ = -40.08 ± 272.03 ng/L), and increased after open surgery (d₁ = 27.38 ± 129.14 ng/L and d₅ = 21.67 ± 234.31 ng/L). The TNF_α levels were not elevated after surgery in both groups. There were no significant differences in the numbers of CD3⁺ and CD56⁺ T lymphocytes and CD3^- and CD56⁺ NK cells, the levels of IgG, IgM, IgA, IL-2, IL-6 and TNF_α between the two groups (P > 0.05).

CONCLUSION: There are no differences in immune responses between the patients having laparoscopic total mesorectal excision with anal sphincter preservation and those undergone open surgery for rectal cancer.