Study Finds That Quality Of Colon Cancer Surgery Is An Important Factor In Patient Survival

Main Category: Colorectal Cancer
Also Included In: GastroIntestinal / Gastroenterology;  Cancer / Oncology
Article Date: 24 Sep 2008 - 2:00 PDT

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A research study has suggested for the first time that the quality of surgery for colon cancer is associated with patient survival. UK researchers found marked variability in the plane of surgery - the directions in which dissection is carried out - in operations to remove colon cancers, with direct impact on survival, when they analysed the tissue removed during cancer surgery in nearly 400 patients.

Previous studies have shown that the quality of rectal cancer surgery improves patient outcomes and total mesorectal excision (TME) for rectal cancer has now become the standard surgical procedure for this cancer type. The researchers in this study wanted to see whether the quality of colon cancer surgery could have a similar effect on patient outcomes. They decided to examine whether the removal of an intact colonic mesentery, or mesocolon (the folds of peritoneum that attach the colon to the posterior wall of the abdomen), might minimise the risk of cancer spread. To test this, they carefully examined all resections for primary colon adenocarcinoma carried out at one UK hospital, Leeds General Infirmary, between 1 January 1997 and 30 June 2002. They photographed all of the specimens of tissue removed during surgery and graded them according to the plane of mesocolic dissection and followed up the patients to see if this was associated with five-year survival.

The study identified a total of 521 cancers. Nearly one-quarter of these (122 specimens) were excluded because there were no photographic images or insufficient images to allow grading of the surgery, leaving 399 specimens for analysis. The researchers graded the surgery using a system initially developed for the Medical Research Council Conventional versus Laparoscopic Assisted Surgery In patients with Colorectal Cancer (CLASSIC) trial. This classified surgery as being in the muscularis propria plane, which was considered a 'poor' plane of surgery, with little bulk to the mesocolon and disruptions extending down into the muscularis propria (the inner circular and outer longitudinal muscle layers of the colon wall); the intramesocolic plane, which was judged 'moderate', with moderate bulk to the mesocolon with irregularity but incisions not reaching down to the muscularis propria; or the mesocolic plane, which was considered a 'good' plane of surgery, giving an intact mesocolon with a smooth peritoneal-lined surface.

The new results revealed marked variation in the proportion of each plane of surgery used. Dissection had been carried out along the muscularis propria in just under one-quarter (24%) of the specimens, was intramesocolic in nearly half (44%) and mesocolic in nearly one-third (32%) of specimens. The average cross-sectional area of tissue outside the muscularis propria was significantly higher with mesocolic plane surgery (2181 mm2) than with the intramesocolic (1273mm2) and the muscularis propria plane (1447mm2).

Survival results showed that patients undergoing mesocolic plane surgery had a 15% overall survival advantage at five years when compared with those who had surgery in the muscularis propria plane (hazard ratio 0.57 [95% confidence interval 0.38-0.85, p=0.006) when analysed in univariate analysis.

This association was no longer significant in the multivariate model, which took account of other factors with a significant effect of survival (HR 0.86 [95% CI] 0.56-1.31, p=0.472). However, it remained significant for patients with stage III cancers, who showed a 27% survival advantage at five years if their surgery was carried out in the mesocolic plane (HR 0.45 [95% CI 0.24-0.85], p=0.014). Overall, the planes of surgery and the amount of mesocolon removed were better in left-sided resections than right-sided procedures, which were better than transverse resections (p<0.0001).

The researchers, let by Nicholas West, from the Leeds Institute of Molecular Medicine at the University of Leeds, said: "We have shown that good quality colon cancer surgery by use of mesocolic plane dissection removes more tissue around the tumour, which is associated with a 15% survival advantage at five years, rising to 27% in stage III disease. Improving the plane of dissection might improve survival, especially in patients with stage III disease." They added: "Our study suggests that in stage III disease, twice as many patients will be alive at five years if they are operated on in the mesocolic plane compared with the muscularis propria plane."

The research group concluded: "If this is confirmed by clinical trials, improvement of the plane of dissection might be a new cost-effective method of decreasing morbidity and mortality in patients with colon cancer." The plane of dissection is one of the measures currently being evaluated in the ongoing National Cancer Research Institute Fluoropyrimidine, Oxaliplatin and Targeted Receptor pre-Operative Therapy for colon cancer (FOxTROT) trial in patients with advanced resectable colon cancer.

In an accompanying editorial, Marcel den Dulk and Cornelis van de Velde, from Leiden University Medical Centre, Leiden, Netherlands, considered that the findings on the quality of surgical resection in colon cancer were 'alarming.' They agreed with the study authors that, as for rectal cancer, the quality of surgery seemed to be a very important factor in the prognosis of patients with colon cancer. They suggested that standardised pathological quality assessment of resection specimens of all solid cancers should be implemented in all new oncological trials and in daily clinical practice to provide feedback to surgeons to continuously improve the number of radical resections in the future.

Commenting on the study, Lars Påhlman, Professor of Surgery in the Department of Surgical Sciences, Colorectal unit, University Hospital Uppsala, Sweden, considered that it provided a more thorough evaluation of the pathology of colon cancer than had been carried out previously. He considered that the study findings were likely to apply to other surgical centres. "It pinpoints the necessity of thorough pathology," he suggested. "It is also important that there is a quality assurance in pathology, which has slowly been used in surgery and radiotherapy but not in medical oncology and pathology in cancer care."

"The paper from this center is a paper of excellence regarding the importance of assessing specimens in pathology. Therefore, it is of utmost importance that this systematic evaluation of specimens and their pathology is adopted in all other centres to make it possible to compare results from different centres and trials," Professor Påhlman concluded.

References

West, NP, Morris, EJ, Rotimi, O et al. Pathology grading of colon cancer surgical resection and its association with survival: a retrospective observational study. Lancet Oncology 2008; 9: 857-865.

Den Dulk, M, van de Velde, CJH. Time to focus on the quality of colon-cancer surgery. Lancet Oncology 2008; 9: 815-817.

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