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Background: The aim of this meta-analysis was to assess the impact of operative blood loss on short and long-term outcomes following colorectal cancer surgery. Methods: A systematic literature review and meta-analysis were performed, from inception to the 10th of August 2020. A comprehensive literature search was performed on the 10th of August 2020 of PubMed MEDLINE, Embase, Science Citation Index Expanded, and Cochrane Central Register of Controlled Trials. Only studies reporting on operative blood loss and postoperative short term or long-term outcomes in colorectal cancer surgery were considered for inclusion. Results: Forty-three studies were included, reporting on 59,813 patients. Increased operative blood loss was associated with higher morbidity, for blood loss greater than 150–350 ml (odds ratio [OR] 2.09, p < 0.001) and > 500 ml (OR 2.29, p = 0.007). Anastomotic leak occurred more frequently for blood loss above a range of 50–100 ml (OR 1.14, p = 0.007), 250–300 ml (OR 2.06, p < 0.001), and 400–500 ml (OR 3.15, p < 0.001). Postoperative ileus rate was higher for blood loss > 100–200 ml (OR 1.90, p = 0.02). Surgical site infections were more frequent above 200–500 ml (OR 1.96, p = 0.04). Hospital stay was increased for blood loss > 150–200 ml (OR 1.63, p = 0.04). Operative blood loss was significantly higher in patients that suffered morbidity (mean difference [MD] 133.16 ml, p < 0.001) or anastomotic leak (MD 69.56 ml, p = 0.02). In the long term, increased operative blood loss was associated with worse overall survival above a range of 200–500 ml (hazard ratio [HR] 1.15, p < 0.001), and worse recurrence-free survival above 200-400 ml (HR 1.33, p = 0.01). Increased blood loss was associated with small bowel obstruction caused by colorectal cancer recurrence for blood loss higher than 400 ml (HR 1.97, p = 0.03) and 800 ml (HR 3.78, p = 0.02). Conclusions: Increased operative blood loss may adversely impact short term and long-term postoperative outcomes. Measures should be taken to minimize operative blood loss during colorectal cancer surgery. Due to the uncertainty of evidence identified, further research, with standardised methodology, is required on this important subject. [ABSTRACT FROM AUTHOR]

Aim: The aim was to assess the benefit of adjuvant chemotherapy in high‐risk Stage II colorectal cancer. Method: A systematic literature review and meta‐analysis was performed comparing survival in patients with resected Stage II colorectal cancer and high‐risk features having postoperative chemotherapy vs no chemotherapy. Results: Of 1031 articles screened, 29 were included, reporting on 183 749 participants. Adjuvant chemotherapy significantly improved overall survival [hazard ratio (HR) 0.61, P < 0.0001], disease‐specific survival (HR = 0.73, P = 0.05) and disease‐free survival (HR = 0.59, P < 0.0001) compared to no chemotherapy. Adjuvant chemotherapy significantly increased 5‐year overall survival (OR = 0.53, P = 0.0008) and 5‐year disease‐free survival (OR = 0.50, P = 0.001). Overall survival and disease‐free survival remained significantly prolonged during subgroup analysis of studies published from 2015 onwards (HR = 0.60, P < 0.0001; HR = 0.65, P = 0.0001; respectively), in patients with two or more high‐risk features (HR = 0.59, P = 0.0001; HR = 0.70, P = 0.03; respectively) and in colon cancer (HR = 0.61, P < 0.0001; HR = 0.51, P = 0.0001; respectively). Overall survival, disease‐specific survival and disease‐free survival during subgroup analysis of individual high‐risk features were T4 tumour (HR = 0.58, P < 0.0001; HR = 0.50, P = 0.003; HR = 0.75, P = 0.05), < 12 lymph nodes harvested (HR = 0.67, P = 0.0002; HR = 0.80, P = 0.17; HR = 0.72, P = 0.02), poor differentiation (HR = 0.84, P = 0.35; HR = 0.85, P = 0.23; HR = 0.61, P = 0.41), lymphovascular or perineural invasion (HR = 0.55, P = 0.05; HR = 0.59, P = 0.11; HR = 0.76, P = 0.05) and emergency surgery (HR = 0.60, P = 0.02; HR = 0.68, P = 0.19). Conclusion: Adjuvant chemotherapy in high‐risk Stage II colorectal cancer results in a modest survival improvement and should be considered on an individual patient basis. Due to potential heterogeneity and selection bias of the included studies, and lack of separate rectal cancer data, further large randomized trials with predefined inclusion criteria and standardized chemotherapy regimens are required. [ABSTRACT FROM AUTHOR]