Curative surgery for obstruction from primary left colorectal carcinoma: primary or staged resection?

BACKGROUND

In 8 to 29% of patients with colorectal carcinoma, obstruction is the main symptom at diagnosis, and 85% of patients undergoing emergency colorectal surgery have obstruction from colorectal carcinoma. The prognosis of patients who undergo emergency surgery for obstruction is often poor. So far, two types of surgical approach have been used for this condition: primary resection (primary anastomosis or Hartmann's procedure) with simultaneous treatment of carcinoma and obstruction, or staged resection (treatment of the obstruction prior to resection).However, neither strategy has been found to have any advantages over the other.

OBJECTIVES

To ascertain whether primary resection in patients with obstruction from left colorectal carcinoma has advantages over staged resection in terms of morbidity and mortality.

SEARCH STRATEGY

Electronic database searches of Cochrane Controlled Trials Register, Medline, Cancerlit, Embase. Hand searching of the most important journals in the fields of oncology and surgery from 2003 and onward until the time of writing.

SELECTION CRITERIA

Randomised Clinical Trials (RCT) and Controlled Clinical Trials (CCT), in which a group of patients who undergo primary resection for intestinal obstruction from left primary colorectal carcinoma is compared with a group of patients who undergo staged resection for the same condition. Since only one study of this type was available, we considered all other studies, except for case-controls, on the basis of the best possible available evidence. Studies were considered without language restrictions.

DATA COLLECTION AND ANALYSIS

Two reviewers (GLDS, CG) examined all the citations and abstracts derived from the electronic search strategy. Reports of potentially relevant trials were retrieved in full. Both reviewers independently applied the selection criteria to trials reports. Reviewers were not blind to the names of institutions, journals or authors of trials. A third opinion (SP, ML) was obtained to resolve disagreements.

MAIN RESULTS

We identified 2043 citations: Medline 1205, Embase 635, Cancerlit 203. One study for potential inclusion was identified, but was then excluded (Kronborg 1995).

REVIEWERS' CONCLUSIONS

The limited number of identified trials together with their methodological weaknesses do not allow a reliable assessment of the role of either therapeutic strategy in the treatment of patients with bowel obstruction from colorectal carcinoma. It would appear advisable to conduct high quality large scale RCT to establish which treatment is more effective. However, it is doubtful whether they could be carried out in a timely and satisfactory way in this particular surgical context.

Curative surgery for obstruction from primary left colorectal carcinoma: primary or staged resection?

BACKGROUND

In 8 to 29% of patients with colorectal carcinoma, obstruction is the main symptom at diagnosis, and 85% of patients undergoing emergency colorectal surgery have obstruction from colorectal carcinoma. The prognosis of patients who undergo emergency surgery for obstruction is often poor. So far, two types of surgical approach have been used for this condition: primary resection (primary anastomosis or Hartmann's procedure) with simultaneous treatment of carcinoma and obstruction or staged resection (treatment of the obstruction prior to resection). However, neither strategy has been found to have any advantages over the other.

OBJECTIVES

To ascertain whether primary resection in patients with obstruction from left colorectal carcinoma has advantages over staged resection in terms of morbidity and mortality.

SEARCH STRATEGY

Electronic database searches of Cochrane Controlled Trials Register, Medline, Cancerlit, Embase. Hand searching of the most important journals in the fields of oncology and surgery from the year 2000 until the time of writing.

SELECTION CRITERIA

Randomised Clinical Trials (RCT) and Controlled Clinical Trials (CCT), in which a group of patients who undergo primary resection for intestinal obstruction from left primary colorectal carcinoma is compared with a group of patients who undergo staged resection for the same condition. Since only one study of this type was available, we considered all other studies, except for case-controls, on the basis of the best possible available evidence. Studies written in English, French, German and Italian and, where necessary, other languages, were considered.

DATA COLLECTION AND ANALYSIS

Two reviewers (GLDS, CG) examined all the citations and abstracts derived from the electronic search strategy. Reports of potentially relevant trials were retrieved in full. Both reviewers independently applied the selection criteria to trials reports. Reviewers were not blind to the names of institutions, journals or authors of trials. A third opinion (SP, ML) was obtained to resolve disagreements.

MAIN RESULTS

The electronic database searches yielded a total of 1412 citations: Medline 1026, Embase 386. From these, one study for potential inclusion was identified, but was then excluded.

REVIEWER'S CONCLUSIONS

The limited number of identified trials together with their methodological weaknesses do not allow a reliable assessment of the role of either therapeutic strategy in the treatment of patients with bowel obstruction from colorectal carcinoma. It would appear advisable to conduct high quality large scale RCT to establish which treatment is more effective. However, it is doubtful whether they could be carried out in a timely and satisfactory way in this particular surgical context.

Genetic effects of chromium tannins

Seventeen tannins used in the hide and leather industry, most of which contain mainly Cr(III) sulphates, were tested for the ability to directly induce gene mutations in Salmonella typhimurium (TA 100 strain) and chromosomal effects (sister chromatid exchanges, SCE) in cultured hamster cells (CHO line). Total chromium [Cr(III) + Cr(VI)] content and contaminating Cr(VI) were determined spectrophotometrically by reaction with diphenylcarbazide. None of the tested compounds induced gene mutations, whereas eight tannins were able to increase significantly the frequency of SCE. A contamination with Cr(VI) was detected in four compounds (from 30 up to 100 parts of Cr(VI) per 10(6) parts of compound), insufficient to be revealed by the Salmonella assay but sufficient to account for the observed SCE increase. On the other hand, the increase of SCE induced by the other four tannins could not be explained by the level of Cr(VI) contamination, and can be ascribed to other impurities present in those industrial compounds. These four tannins did not induce gene mutations in the S. typhimurium assay even when strain TA 98 was used in addition to TA 100, independently of microsomal activation. By prolonging the time of the SCE assay from 30 to 48 h in order to facilitate Cr(III) endocytosis, a significant increase of the SCE frequency was induced by an analytical-grade Cr(III) reagent (chromium chloride), absolutely uncontaminated by Cr(VI), as well as by three Cr(III) tannins, otherwise inactive in the SCE assay.

Effects of nitrilotriacetic acid on the induction of gene mutations and sister-chromatid exchanges by insoluble chromium compounds

The influence of nitrilotriacetic acid trisodium salt (NTA) on the mutagenic and clastogenic activity of several water-insoluble or poorly soluble chromium compounds was determined by means of the Salmonella/microsome assay (plate test on TA100 strain) and the sister-chromatid exchange (SCE) test in mammalian cell cultures (CHO line). NTA in itself did not induce gene mutations nor did it increase the frequency of SCE. Cr(VI) compounds (Pb, Ba, Zn, Sr and Ca chromates) and an industrial Cr(VI) pigment, chromium orange (containing PbCrO4 PbO), were inactive or scarcely active mutagens in the Salmonella/microsome test when dissolved in water, but they were increasingly mutagenic when solubilized by 0.5 N NaOH or NTA (10 or 100 mg/ml). Also, the mutagenic activity of Cr(VI), contaminating an industrial Cr(III) pigment (chromite), was slightly enhanced by NTA. Mutagenicity of chromates was correlated with the amounts of Cr(VI) solubilized by NTA or alkali, as determined by the colorimetric reaction with diphenylcarbazide and atomic absorption spectrophotometry, and was decreased by incubation with microsomes, due to reduction of Cr(VI) to the genetically inactive Cr(III) form. In the SCE assay, the insoluble or poorly soluble Ba, Zn, Sr and Ca chromates and the insoluble Cr(VI) pigments zinc yellow (containing ZnCrO4 Zn(OH2], chromium yellow and molybdenum orange (both containing PbCrO4) were directly clastogenic due to cellular endocytosis taking place in prolonged treatments, and NTA significantly increased their chromosome-damaging activity.

Mutagenic activity and polycyclic aromatic hydrocarbon levels in urine of workers exposed to coal tar pitch volatiles in an anode plant

The mutagenicity of urinary extracts and the excretion of PAH from workers occupationally exposed to coal tar pitch volatiles in an anode plant were analyzed. Mutagenicity of the urinary extracts was measured by means of the plate test using S. typhimurium strain TA 98. After concentration, hydrolysis and reduction of the urine samples, PAH levels were measured by high resolution gas chromatography/mass spectrometry. No significant difference was found in the mutagenicity of the urinary extracts of non-smokers occupationally exposed to PAH as compared with the controls. Low PAH concentrations were found in the urine of the exposed subjects, which lends further support to the negative results obtained with the Ames' test. The increase of urinary PAH excretion, in relation to occupational exposure, was mainly due to the less mutagenic, low molecular weight compounds.