Association of Dietary Intake and Biomarker of α-Linolenic Acid With Incident Colorectal Cancer: A Dose-Response Meta-Analysis of Prospective Cohort Studies

Background and Objective

There is keen interest in better understanding the impacts of alpha-linolenic acid (ALA), a plant-derived n-3 fatty acid, in ameliorating the development of cancer; however, results of several prospective cohorts present an inconsistent association between ALA intake and the incident colorectal cancer (CRC). We aimed to investigate the summary association of dietary intake and biomarkers of ALA with CRC risk based on the prospective cohorts.

Methods

Pertinent prospective cohorts were identified in Cochrane Library, PubMed, and EMBASE from inception to February 2022. Study-specific risk ratios (RRs) with 95% confidence intervals (CIs) for comparing the top with the bottom quartiles of ALA levels were combined using a random-effects model. Nonlinear dose-response relationships of ALA levels in diet and blood with CRC risk were assessed using the restricted cubic spline models, respectively.

Results

Over the duration of follow-up with a median of 9.3 years ranging from 1 to 28 years, 12,239 CRC cases occurred among 861,725 participants from 15 cohorts (11 studies on diet and 5 studies on biomarkers including 4 on blood and 1 on adipose tissue). The summary RR was 1.03 (95% CI: 0.97, 1.10; I²: 0.00%) for dietary intake and 0.83 (95% CI: 0.69, 0.99; I²: 0.00%) for biomarker. Each 0.1% increase in the levels of ALA in blood was associated with a 10% reduction in risk of CRC (summary RR: 0.90, 95% CI: 0.80, 0.99; I²: 38.60%), whereas no significant dose-response association was found between dietary intake of ALA and the incident CRC (p for non-linearity = 0.18; p for linearity = 0.24).

Conclusions

Blood levels of ALA were inversely and linearly associated with the risk of CRC, which suggested that increased intake of ALA to improve circulating levels was beneficial for CRC prevention.

Application of anticancer agent embolism in Miles' operation

Presented in this paper is a report of the prospective studies on rectal cancer. By using the method of anticancer agent gelatin sponge to form embolism and by ligating the bilateral arteria iliaca internal, we performed Miles' operation on 64 cases of rectal cancer. Only 24 cases in the control group had Miles' operation. The amount of blood transfused during operation, duration of operation, days of hospitalization, infection rate of incision on the peritoneum, and relapse rate in treated group were significantly different from those in the control group (P < 0.05).

The relationship between the morphology of nucleus of liver cells and the liver functions and prognosis of portal hypertension due to hepatic cirrhosis

The morphology of nucleus of liver cells from 30 patients with portal hypertension due to hepatic cirrhosis and 5 normal persons were measured using an image analyzer coupled with a computer. It was found that the diameters, perimeters, areas and form factor (FF) of the nucleus of liver cirrhosis portal hypertension patients were significantly increased as compared with those of the normal subjects (P < 0.05 or P < 0.01). There was a very significant difference in this parameters between the normal persons and patients with Child-Pugh A liver function or patients with Child-Pugh C liver function (P < 0.01 for both). Significant difference in these parameters existed between the normal persons or patients with Child-Pugh A liver function and patients with liver function of Child-Pugh B (P < 0.05). No significant difference in the parameter of optic density (OD) were found between the normal persons and patients with impairment of liver function of varying degrees (Child-Pugh Classification) (P > 0.05). Our results suggest that the hepatocytes of patients with portal hypertension due to hepatic cirrhosis became juvenile and the morphology of the hepatocytes of patients with impairment of liver function of Child-Pugh C changed obviously. The enlargement and sparsity of nucleus of hepatocytes as revealed by pathological examination is a sign of severe impairment of liver function.

Experimental study on hepatic inflow occlusion in rabbits

To evaluate the effect of hepatic inflow occlusion on the liver remnant, three methods of inflow occlusion of the right outside lobe of liver, which was finally resected, were performed in 30 rabbits. The mortality rate of 12 animals (6 in Group I and 6 in Group II) undergone 30 minutes of portal triad clamping (PTC) and selective hepatic artery reserving (SHAR) was both 66.7%. No death occurred in Group III (PTC, n = 6) and IV (SHAR, n = 6) for 20 minutes of hepatic ischemia, but with an irreversible damage to the hepatocytes. The level of serum glutamic-pyruvic transaminase (GPT) in Groups III and IV animals rose to 282.17 U/L and 155.33 U/L on the first postoperative day and thereafter declining slowly to the preoperative level on the 5th and 3rd days, respectively. In Group V with selective hemihepatic vascular occlusion (SHHVO) serum GPT showed only temporary mild rise (112.83 U/L) on the first postoperative day and no hepatic pathologic change appeared. It is obvious that the function of the liver remnant can be best preserved during hepatic resection under SHHVO.

Experimental study on hepatic vascular exclusion with atrioportacaval shunt in dogs

The main effects of hepatic vascular exclusion (HVE) on the body are hemodynamic changes and metabolic disorders. We developed a new technique--atrioportacaval shunt (APCS) both to increase the blood--return volume and to decompress the portal system and the inferior vena cava below the occlusion during HVE in canine. Experimental results showed that HVE-APCS is characteristic of simplicity and safety. During HVE-APCS central venous pressure (CVP), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), pulmonary capillary wedged pressure (PCWP) and pulmonary vascular resistance (PVR) remained almost stable while cardiac output (CO) decreased by 34.5-45.6% and systemic vascular resistance (SVR) increased by 46.8-65.7%. The recirculation injury to ischemic liver was mild owing to concomitant decompression of the portal system. It may be concluded that HVE-APCS is an ideal method to control the bleeding from the major hepatic veins and retrohepatic vena cava.

[An experimental study on bloodless hepatic resection under vascular exclusion with atrioportacaval shunt (HVE-APCS)]

We developed a new technique--atrioportacaval shunt (APCS) both to increase the blood-return volume and to decompress the portal system and the inferior vena cava below the occlusion during hepatic vascular exclusion (HVE) in canine. A balloon catheter with a hole on its side was inserted up into inferior vena cava (IVC) through a venotomy just above the confluence of the bilateral renal veins, until the tip with the balloon was at the level of diaphragm. The caudal outside IVC was passed into portal vein. HVE-APCS was performed with clamping hepatic pedicle, tightening an umbilical tape around IVC immediately above the confluence of bilateral suprarenal veins, and finally inflating the balloon. Blood of the portal system and IVC below the occlusion was allowed to return to the right atrium through the catheter. The experimental results showed that HVE-APCS is characteristic of simplicity and safety, and of less harmful effect on the systemic hemodynamics. Because of the portal decompression, the recirculation injury to the ischemic liver was mild. It is concluded that HVE-APCS is an ideal method to control the bleeding from the major hepatic veins and retrohepatic vena cava.

Application of CDFI and portal system pressure measurement in the study of portal hypertension hemodynamics

It has been discovered in portal system hemodynamics research using CDFI and pressure measurement, that among 40 portal hypertension patients the demonstrating rate of left gastric vein (LGV) was 77.5%, and all were hepatofugal. The demonstrating rates of spontaneous splenorenal vein shunt collaterals and of patency umbilical vein (UV) with blood signal were 85%, 12.5% respectively, and the thrombosis rate of portal system was 10%. Blood flow direction of main portal vein (MPV) in all patients was hepatopetal, and one case of superior mesenteric vein (SMV) and another one of splenic vein (SV) were hepatofugal. The patients with MPV thrombosis or portal system hepatofugal should be operated on by shunt. Shunt capacity of portal vein in gastroplenic region was 34.07% on average. This demonstrated that devascularization was applicable. Internal diameter, blood capacity and time average velocity (TAV) of the left portal vein (LPV) and right portal vein (RPV) with portal hypertension were almost equal, their difference being not significant (P > 0.2). This should be a basis for the diagnosis of portal hypertension. Free portal pressure (FPP) and internal diameter, blood capacity and TAV of MPV, SV, SMV, LGV were not correlative with each other.