925 Maintenance of Elective Surgical Care During Covid-19 Pandemic

Introduction

Recent publications demonstrate significant morbidity in surgical patients with concurrent COVID-19 infection. This, combined with the redistribution of resources to support the pandemic, led to abrupt cessation in planned operating. COVID-19-free ‘cold’ sites were established to enable elective surgery to resume with reduced risk. We evaluate the outcomes and limitations of a newly established cold site.

Method

Data were collected retrospectively for all patients operated between June and September 2020 by either General Surgery or Urology. Primary outcomes were 30-day COVID-19 infection and 30-day mortality. Secondary outcomes included length of stay, 30-day complications, and need for transfer to ‘hot’ hospital sites.

Results

881 patients were included. No patients had a positive COVID-19 test within 30 days of their operation. 30-day mortality was 0.01% (n = 1). The mean (+/-SD) length of stay was 1.69+/-3.42 days. 12.15% (n = 107) of patients experienced a complication within 30 days and 11.7% (n = 103) were readmitted within 30 day of discharge. 3.3% (n = 29) of patients required transfer to a ‘hot’ hospital site. 44.8% of these were admitted to level 2 or level 3 care, 17.2% required total parenteral nutrition, and 20.7% returned to theatre.

Conclusions

‘Cold’ surgical sites are effective in preventing peri-operative COVID-19 infection. Elective surgery can therefore continue safely through the pandemic with such precautions. Further development of on-site resources, including provision for total parenteral nutrition and access to higher level care, will help to minimise the need for patient transfers to COVID-19 exposed sites.

Necrotizing fasciitis of chest wall complicating empyema thoracis

Necrotizing fasciitis affecting the chest wall is a rare condition and carries high mortality. It spreads rapidly, requiring early diagnosis and immediate extensive surgical debridement. The case of a 32 year old man afflicted with this uncommon condition following tube thoracostomy for empyema thoracis is described and literature reviewed.

Glutathione S-transferase GSTT1 genotypes and susceptibility to cancer: studies of interactions with GSTM1 in lung, oral, gastric and colorectal cancers

Allelism in glutathione S-transferase GSTM1 and GSTT1 has been suggested as a risk factor in various cancers. Accordingly, we describe a group of case-control studies carried out to identify associations between GSTT1 genotypes and susceptibility to lung, oral, gastric and colorectal cancers. The frequencies of the putatively high risk GSTT1 null genotype were not increased in the lung, oral or gastric cancer cases compared with controls but the frequency of this genotype was significantly increased (P = 0.0011, odds ratio = 1.88) in the colorectal cancer cases. No significant interactions between the GSTT1 and GSTM1 null genotypes types were identified in the cancer groups studied. Indeed, no significant associations between GSTM1 genotypes and susceptibility were identified though further evidence was obtained that the protective effect of GSTM1*A and GSTM1*B is not equal. The data complement studies showing that GSTT1 null is associated with an increased susceptibility to total ulcerative colitis and suggests that this enzyme is important in the detoxification of unidentified xenobiotics in the large intestine.

Polyadenylation polymorphism in the acetyltransferase 1 gene (NAT1) increases risk of colorectal cancer

Exposure to carcinogens present in the diet, cigarette smoke, or the environment may be associated with increased risk of colorectal cancer. Aromatic amines (aryl- and heterocyclic) are a class of carcinogens that are important in these exposures. These compounds can be N- or O-acetylated by the NAT1 or NAT2 enzymes, resulting in activation or in some cases detoxification. Recent studies have shown that both NAT2 and NAT1 genes exhibit variation in human populations and that rapid acetylation by the NAT2 enzyme may be a risk factor for colorectal cancer. In this study we have analyzed for genetic polymorphism in both NAT1 and NAT2 in a group of 202 colorectal cancer patients and 112 control subjects from Staffordshire, England. We find significantly increased risk (odds ratio, 1.9; 95% confidence interval, 1.2-3.2; P = 0.009) associated with the NAT1*10 allele of NAT1, an allele that contains a variant polyadenylation signal. Individuals with higher stage tumors (Duke's C) were more likely to inherit this variant allele (odds ratio, 2.5; 95% confidence interval, 1.3-4.7; P = 0.005). In contrast, rapid acetylation genotypes of NAT2 were not a significant risk factor in this English population. However, we found that the risk associated with the NAT1 variant allele (NAT1*10) was most apparent among NAT2 rapid acetylators (odds ratio, 2.8; 95% confidence interval, 1.4-5.7; P = 0.003), suggesting a possible gene-gene interaction between NAT1 and NAT2 (test for interaction; P = 0.12). This is the first study to test for cancer risk associated with the NAT1 gene, and these positive findings suggest that NAT1 alleles may be important genetic determinents of colorectal cancer risk.

Enteric alpha-1-antitrypsin loss and comparison with Okokit II and Haemoccult for the detection of colorectal cancer

Faecal samples from patients with symptomatic colorectal cancer (n = 19) and from control subjects (n = 54) were analysed for alpha-1-antitrypsin (A1AT) and compared with Haemoccult and Okokit II. A1AT was also measured in paired samples of normal colonic mucosa and cancer tissue (n = 16) and in media from four human colorectal cell lines (COLO 320 DM, SW620, HT29, LS 174T). Faecal A1AT concentrations were greater than controls (P < 0.0001) and detected 12 (63%) patients with cancer compared to 10 (53%) by Okokit II and 7 (37%) by Haemoccult (P > 0.05). A1AT concentrations from colonic mucosa (median, range: 0.46, 0.17-0.79 mg/g wet wt) were greater (P = 0.01) than cancer tissue (0.29, 0.13-0.74 mg/g wt wt). Adjusting for albumin, A1AT concentrations from mucosa (12.0, 3.8-32.2 mg/g albumin) remained greater (P = 0.003) than for cancer tissue (5.9, 2.4-21.4 mg/g albumin). A1AT was not detected in any of the cell-line media. The most likely mechanisms for increased faecal A1AT concentrations, apart from increased blood loss, are increased cell turnover or leakage from epithelial tight junctions. The use of faecal A1AT measurement for the detection of colorectal cancer deserves further assessment.

Reduction of mucosal crypt cell proliferation in patients with colorectal adenomatous polyps by dietary calcium supplementation

The crypt cell production rate was measured in 14 patients with adenomatous colorectal polyps, 17 patients with colorectal cancer and 12 control subjects. The median (interquartile range) rate (cells per crypt per hour) was found to be significantly higher (P less than 0.001) in the polyp (2.45 (1.94-3.20)) and cancer (3.01 (2.35-3.68)) groups compared with controls (1.25 (0.70-1.85)). A double-blind cross-over study was performed in patients with adenomatous polyps consisting of 2 months' treatment, 2 weeks' washout, followed by 2 months' treatment with dietary calcium supplementation (1.25 g day-1) versus placebo. A significant reduction in the crypt cell production rate occurred with calcium treatment compared with the placebo (1.25 (0.6-2.25) versus 2.15 (1.58-3.08) cells per crypt per hour, P = 0.035). This study demonstrates a significant reduction in mucosal cell proliferation by dietary calcium supplementation in patients with adenomatous polyps. Such treatment may be worthy of further investigation in patients at high risk of developing colorectal polyps.