The impact of structural factors in colon and rectal cancer surgery

Abstract: The aim of this thesis was to investigate the importance and effect of some key-structural factors on outcome of colorectal cancer surgery.Considerable improvements in the treatment of colorectal cancer, i.e. radiotherapy, chemotherapy and operative technique, have taken place since the beginning of the 80s. Recent years have also seen the introduction of multidisciplinary team (MDT) meetings in routine care, although evidence that this has benefitted treatment selection and outcome is weak. A challenge still remaining, regarding colon cancer surgery, is to improve outcome for the large number of patients presenting as an emergency. Outcome in the emergency situation remains worse in both the short- and long-term perspective compared to elective cases. Although studied extensively, the impact of surgeon’s case-load and degree of specialisation on outcome of surgery remains unclear.The following specific factors were studied: the effect of surgeon’s case-load and degree of specialisation on long-term survival in a well-defined, population-based, and recent cohort; the impact of surgeon’s case-load or degree of specialisation on the number of lymph nodes harvested in routine colon cancer surgery; predictors of preoperative discussion of rectal cancer patients at a MDT conference in Sweden, and whether or not MDT assessment influences decision-making in the treatment of rectal cancer; factors associated with an increased risk for loco-regional recurrence in patients operated as an emergency for colon cancer, in a population-based cohort.Data from the Swedish Colorectal Cancer Register (SCRCR) and the local (Uppsala/Örebro) ROC-register were used to study the effect of surgeon’s caseload and surgeon’s degree of specialisation on long-term survival. Data from six hospitals in the Uppsala/Örebro health care region were extracted for the periods 1995-2006 for rectal cancer, and 1997-2006 for colon cancer. These data were updated with a surgeon-specific number and competence level as well as other missing data. Colon and rectal cancer were analysed separately and each cancer stage was analysed separately (Stages I and II grouped together). Data on patients who had undergone right-sided hemicolectomy were extracted from these data and used to investigate whether the surgeon’s case-load or degree of specialisation had an impact on the number of lymph nodes harvested. For the study on predictors of discussion at a preoperative MDT conference, data on all patients without known metastatic disease at diagnosis, who underwent elective surgery for rectal cancer 2007-2010 in Sweden, were extracted from the SCRCR. For the study on factors associated with preoperative radiotherapy, two groups were extracted from this cohort and analysed separately. The first group comprised patients who had undergone elective tumour resection with curative intent for pT3c, pT3d, pT4 tumours, and the second comprised patients who had undergone elective tumour resection with curative intent for lymph node-positive tumours. For the study on colon cancer patients operated as an emergency, the local colon cancer registry for the Stockholm-Gotland health care region was used to identify all colon cancer patients subjected to emergency resection with curative intent in this region 1997-2007. Patient records with missing information were updated. The impact of reason for emergency resection, time from admission to surgery, daytime versus night-time operation, ASA score, blood loss, and T- and N-stages on the risk for locoregional recurrence was assessed.When the highest degree of specialisation of surgeons participating in the operation was a non-colorectal surgeon, there was a slightly lower long-term survival for rectal cancer Stages I-II (HR 2.03; 95%CI 1.05-3.92). Apart from this, neither the degree of specialisation nor case-load was associated with better survival. Surgeons with colorectal accreditation were associated with a signifcantly higher proportion of patients having 12 or more lymph nodes harvested from surgical specimens after right-sided hemicolectomy in both non-adjusted and multivariate analyses, as was also university pathology department. Emergency surgery did not affect the lymph node yield. The number of rectal cancer procedures performed per year at each hospital (hospital volume) was the main predictor of MDT evaluation. Patients treated at hospitals with <29 procedures per year had an odds ratio (OR) for MDT evaluation of 0.15. Tumour stage and age also influenced the chance of MDT evaluation. MDT evaluation significantly predicted the likelihood of being treated with preoperative radiotherapy in patients with pT3c-pT4 tumours (OR 5.06) and lymph node-positive tumours (OR 3.55), even when corrected for co-morbidity and age. The only factor tested, apart from stage, influencing the risk for local recurrence after emergency colon cancer surgery was the indication for emergency surgery; perforations of the colon being a higher risk with a HR of 1.96 (95%CI 1.12-3.43).Case-load and degree of specialisation of the surgeon were found not to be important predictors of outcome in colorectal cancer surgery in this cohort. This suggests that there are other structural-related factors that are more important for outcome in colon and rectal cancer. The degree of specialisation of the surgeon did, however, influence the number of lymph nodes harvested from specimens obtained during routine right-sided colon cancer surgery, which might indicate that a higher degree of specialisation is associated with more extensive surgery. Patients with rectal cancer treated at high-volume hospitals were more likely to be discussed at a MDT conference. This in turn was identified as an independent predictor of treatment with adjuvant radiotherapy. MDT evaluation is thus a structural factor with a potentially greater impact on treatment and outcome than surgeon’s caseload and degree of specialisation, at least for patients with rectal cancer. Structural-related risk factors that were expected to predict outcome in emergency colon cancer surgery had no significant influence on the risk for locoregional recurrence.