This study shows that neither risk of recurrence nor survival after emergent colon cancer resection was influenced by the specialization of the surgical team performing the operation. No difference in postoperative morbidity or mortality rate was noted. Patients operated by emergency teams had a higher rate of permanent stoma after 3 years compared with patients operated by colorectal surgical teams or general surgeons. This may reflect that colorectal surgeons are more prone to opt for primary anastomosis and diverting ileostomy in left-sided resections.

The rate of microscopically radical resections did not differ between the groups. In contrast, a difference in number of examined lymph nodes was noted, which, however, did not reflect in any difference in risk of recurrence. The difference was small and could as well depend on the pathology as the surgery. Further, all groups had totally sufficient numbers of examined lymph nodes and we perceive the noted difference not to be of clinical importance. Notably, a borderline difference in N-stage, with more N0 in the GST group, was noted. Although the reason for this is elusive, it might reflect a stage migration albeit the sufficient number of examined lymph nodes as any difference in N-stage depending on geography is less likely. Nevertheless, as the whole groups of patients were analyzed, any stage migration should not impact the primary endpoints, survival and recurrence rate.

Several studies have shown an association between outcome and surgical sub-specialization and surgical volume, respectively, in elective surgery for colon cancer [12, 19,20,21,22], although not all were consistent. For example, Hall et al. performed a retrospective registry-based study of 21,432 patients who had undergone elective operation for colon cancer and 5893 operated on for rectal cancer either by colorectal specialists or general surgeons. Colorectal surgeons performed 16.3% of the colon and 27% of the rectal resections. They found no difference in overall 5-year disease-specific survival (DSS) between the specialties except in stage II rectal cancer in a multivariate analysis. When the analysis was limited to high-volume surgeons only, the results remained the same [2].

The impact of specialization and caseload in the emergency settings is much less studied and unclear. Kwan et al. studied the impact of hospital volume on 30-day postoperative mortality following emergency colorectal surgery in 864 patients, of which 63.8% had colon cancer, operated in 15 different hospitals. The hospitals were grouped into low, medium and high operative volume according to caseload. The colorectal POSSUM scoring system was used to adjust for difference in case-mix in the study. Thirty-day mortality was 16.3% without any statistical difference in mortality between hospitals of different case volume [23], a finding in line with our result. Kulyat et al. studied short-term outcomes in patients undergoing emergent colectomies by colorectal surgeons compared to general or emergency care surgeons in 3 academic hospitals. A propensity score matching was performed with 238 patients in each group. Operations performed by colorectal surgeons were associated with significantly lower rates of 30-day mortality (6.7% vs 16.4%, p = 0.001) and postoperative morbidity (45.0% vs 56.7%, p = 0.009). However, only 13.0% of the patients had a malignant disease [24]. A large population-based registry study from the UK showed that emergency laparotomy performed by consultants without a special interest in colorectal surgery had an increased adjusted 30-day mortality risk (OR 1.23, 95 CI 1.13–1.33) as well as increased risk of re-operation (OR 1.13, CI 1.05–1.20) compared to consultants with special colorectal interest [25].

A Swedish registry-based retrospective study on 13,365 patients operated on for colon cancer between 2007 and 2010 focused on formal competence of the most senior surgeon attending the procedure irrespective of surgical team or hospital volume, of which 21.9% were emergency procedure. The result showed superior five-year overall survival in patients operated by colorectal surgeons (36.6%) compared to general surgeons (33.4%) (p < 0.05). However, after adjusting for 30- and 90-day mortality, no statistically significant difference was noted. Hence, the difference in long-term survival was explained by a lower postoperative mortality in the group of patients operated by colorectal surgeons. However, it is unclear to what degree the improved postoperative mortality rate was dependent on the specialization of the surgeon or the competence of the whole team, caring for the patient postoperatively. Probably this result was also affected by a case-mix, such as more frail and severely ill patients, e.g., with peritonitis, had to be operated during on-call and thus by younger less qualified surgeons [26].

Moreover, high-volume hospitals not only have more colorectal specialist, but also better intensive care and a lower rate of failure to rescue (FTR) [27,28,29] which reflects the rate of mortality after major complications. Postoperative complications greatly affect short- and long-term survival after surgery for colon cancer and even more so in patients operated on acutely [30]. Preoperative comorbidities, such as congestive heart failure and chronic renal failure, have been associated with higher rates of FTR in emergency general surgery [31]. These patients may neither tolerate fluid shifts nor the resuscitation required to restore physiologic parameters postoperatively [31]. Hospital factors also influence FTR. Multidisciplinary approach is needed for identification of at-risk patients, prevention of avoidable complications, recognition of unavoidable complications and prompt intervention in attempt to prevent avoidable death [31, 32]. Henneman et al. evaluated the association between structural hospital characteristics (hospital volume, teaching status and intensive care facilities (ICU) and FTR after colorectal cancer surgery. Only higher levels of ICU facilities were associated with lower FTR rates (OR 0.72; 95% CI 0.65–0.88) in multivariate analysis [28]. Intensive care in Sweden is generally of high quality and quite standardized between hospitals which might explain why we did not find any difference in in-hospital mortality between the groups in the present study.

The Union of International Cancer Control (UICC) recommends the evaluation of a minimum of 12 LNs for appropriate staging of patients with pN + disease [33]. Some previous studies report insufficient examined lymph nodes in the emergent setting [34], perhaps due to technical difficulties and instable patients [35], with a subsequent risk of not having adjuvant chemotherapy, as the indication for adjuvant chemotherapy is determined foremost by node positivity. However, also other risk factors for recurrence, including emergent operation constitute indications for adjuvant treatment [36]. In the present study, no difference in the proportion of patients given adjuvant chemotherapy was noted, albeit a numerical difference in N0 stage, probably due to that emergent resection is an indication for adjuvant chemotherapy.

The weakness of the present study is the retrospective design, implying a risk of selection bias although known confounders, such as ASA score, age and TNM stage were adjusted for in the multivariate analysis. Although the five larger hospitals had dedicated teams for colorectal and emergency surgery, there was some overlapping of surgeon´s specialization, especially in the GST where over half of the surgeons had colorectal qualification.