Risk of Postoperative Ischemic Stroke and Myocardial Infarction in Patients Operated for Cancer.

BACKGROUND: Risk assessment for ischemic stroke (IS) and myocardial infarction (MI) is done routinely before surgery, but the increase in risks associated with surgery is not known. The aim of this study is to assess the risk of arterial ischemic events during the first year after oncological surgery. METHODS: We used Swedish healthcare databases to identify 443,300 patients who underwent cancer surgery between 1987 and 2016 and 4,127,761 matched comparison subjects. We estimated odds ratios (ORs) for myocardial infarction and ischemic stroke during the hospitalization with logistic regression and calculated 1-year cumulative incidences and hazard ratios (HRs) with 95% confidence intervals (CIs) for the outcomes after discharge. RESULTS: The cumulative incidences of myocardial infarction and ischemic stroke during the first postoperative year were 1.33% and 1.25%, respectively. In the comparison cohort, the corresponding 1-year cumulative incidences were 1.04% and 1.00%. During the hospitalization, the OR for myocardial infarction was 8.81 (95% CI 8.24-9.42) and the OR for ischemic stroke was 6.71 (95% CI 6.22-7.23). After discharge, the average HR during follow-up for 365 days was 0.90 (95% CI 0.87-0.93) for myocardial infarction and 1.02 (95% CI 0.99-1.05) for ischemic stroke. CONCLUSIONS: We found an overall increased risk of IS and MI during the first year after cancer surgery that was attributable to events occurring during the hospitalization period. After discharge from the hospital, the overall risk of myocardial infarction was lower among the cancer surgery patients than among matched comparison subjects.

Quality of life and patient reported symptoms after colorectal cancer in a Swedish population.

AIM: A proportion of patients treated for colorectal cancer have impaired quality of life (QoL) but it is uncertain if the level of QoL differs from the corresponding background population. This population-based cohort study aimed to evaluate health-related QoL in colorectal cancer patients and compare their QoL with that of a Swedish reference population. METHODS: Patients who underwent surgery for colorectal cancer Stages I-III in the Stockholm-Gotland region in 2013-2015 received the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and the QLQ-CR29 questionnaires and the low anterior resection syndrome score, 1 year after surgery. Patient and tumour data were collected from the Swedish Colorectal Cancer Registry. The patient cohort was matched to a Swedish reference population regarding EORTC QLQ-C30. Global QoL was compared to the reference population and a patient group with impaired QoL was defined. Detailed patient-reported outcomes were analysed in relation to global QoL in the patient cohort. RESULTS: A total of 925 patients returned the questionnaires and 358 patients (38.70%) reported a clinically relevant impaired global QoL compared to the reference population. Patients with impaired QoL reported clinically relevant and statistically significantly more complaints regarding bowel habits, pain and anxiety. After adjustment for sex, age and stoma, anxiety was the strongest predictor for impaired QoL, with OR 6.797 (95% CI 4.677-9.879). CONCLUSION: A substantial proportion of patients treated for colorectal cancer have impaired global QoL. This impairment is strongly associated with several physical symptoms and anxiety.

Long-term oncological outcomes for minimally invasive surgery versus open surgery for colon cancer-a population-based nationwide study with a non-inferiority design.

AIM: The study aimed to compare 5-year overall survival in a national cohort of patients undergoing curative abdominal resection for colon cancer by minimally invasive surgery (MIS) or by the open (OPEN) technique. METHODS: All patients diagnosed between 2010 and 2016 in Sweden with pathological Union International Contre le Cancer Stages I-III colon cancer localized in the caecum, ascending colon, hepatic flexure or sigmoid colon and those who underwent curative right sided hemicolectomy, sigmoid resection or high anterior resection by MIS or OPEN were included. Patients were identified in the Swedish Colorectal Cancer Registry from which all data were retrieved. The analyses were performed as intention-to-treat and the relationship between surgical technique (MIS or OPEN) and overall mortality within 5 years was analysed. For the primary research question a non-inferiority hypothesis was assumed with a statistical power of 90%, a one-side type I error of 2.5% and a non-inferiority margin of 2%. For the secondary analyses, multilevel survival regression models with the patients matched by propensity scores were employed, adjusted for patient- and tumour-related variables. RESULTS: A total of 11 605 pathological Union International Contre le Cancer Stages I-III patients were included with 3297 MIS (28.4%) and 8308 OPEN (71.6%) and were followed until 31 December 2020. The primary analysis demonstrated superiority for MIS compared to OPEN. The multilevel survival regression analyses confirmed that 5-year overall survival was higher in MIS with a hazard ratio of 0.874 (95% confidence interval 0.791-0.965), and if excluding pT4 the outcome was similar, with a hazard ratio of 0.847 (95% confidence interval 0.756-0.948). CONCLUSION: This observational study demonstrated that MIS was favourable to OPEN with regard to 5-year overall survival. These results support the use of laparoscopic colon cancer surgery in routine practice.

Validation of a diagnostic prediction tool for colorectal cancer: a case-control replication study.

BACKGROUND: Early detection of colorectal cancer (CRC) is crucial for survival. Primary care, the first point of contact in most cases, needs supportive risk assessment tools. We aimed to replicate the Swedish Colorectal Cancer Risk Assessment Tool (SCCRAT) for non-metastatic CRC in primary care and examine if risk factor patterns depend on sex and age. METHODS: 2,920 adults diagnosed with non-metastatic CRC during the years 2015-2019 after having visited a general practitioner the year before the diagnosis were selected from the Swedish Cancer Register and matched with 11,628 controls, using the same inclusion criteria except for the CRC diagnosis. Diagnostic codes from primary care consultations were collected from a regional health care database. Positive predictive values (PPVs) were estimated for the same 5 symptoms and combinations thereof as in the baseline study. RESULTS: The results for patients aged ≥50 years old in the present study were consistent with the results of the SCCRAT study. All symptoms and combinations thereof with a PPV >5% in the present study had a PPV >5% in the baseline study. The combination of bleeding with abdominal pain (PPV 9.9%) and bleeding with change in bowel habit (PPV 7.8%) were the highest observed PPVs in both studies. Similar risk patterns were seen for all ages and when men and women were studied separately. CONCLUSION: This external validation of the SCCRAT for non-metastatic CRC in primary care replicated the baseline study successfully and identified patients at high risk for CRC.

Colon cancer treatment in Sweden during the COVID-19 pandemic: A nationwide register-based study.

AIM: The COVID-19 pandemic has reduced the capacity to diagnose and treat cancer worldwide due to the prioritization of COVID-19 treatment. The aim of this study was to investigate treatment and outcomes of colon cancer in Sweden before and during the COVID-19 pandemic. METHODS: In an observational study, using the Swedish Colorectal Cancer Registry, we included (i) all Swedish patients diagnosed with colon cancer, and (ii) all patients undergoing surgery for colon cancer, in 2016-2020. Incidence of colon cancer, treatments and outcomes in 2020 were compared with 2019. RESULTS: The number of colon cancer cases in Sweden in April-May 2020 was 27% lower than the previous year, whereas no difference was observed on an annual level (4,589 vs. 4,763 patients [-4%]). Among patients with colon cancer undergoing surgery in 2020, the proportion of resections was 93 vs. 94% in 2019, with no increase in acute resections. Time from diagnosis to elective surgery decreased (29 days vs. 33 days in 2020 vs. 2019). In 2020, more patients underwent a two-stage procedure with a diverting stoma as first surgery (6.1%) vs. (4.4%) in 2019 (p = 0.0020) and more patients were treated with preoperative chemotherapy (5.1%) vs. (3,5%) 2019 (p = 0.0016). The proportion of patients that underwent laparoscopic surgery increased from 54% to 58% (p = 0.0017) There were no differences in length of stay, surgical complications, reoperation, ICU-stay or 30-day mortality between the years. CONCLUSION: Based on nationwide annual data, we did not observe adverse effects of the COVID-19 pandemic on colon cancer treatment and short time outcomes in Sweden.

Life with a stoma across five European countries-a cross-sectional study on long-term rectal cancer survivors.

PURPOSE: Stoma-related problems are known to be important to patients and potentially affect everyday life. The prevalence of stoma-related problems in rectal cancer survivors remains undetermined. This study aimed to examine aspects of life with a long-term stoma, stoma management, and stoma-related problems and explore the impact of stoma-related problems on daily life. METHODS: In total, 2262 patients from 5 European countries completed a multidimensional survey. Stoma-related problems were assessed using the Colostomy Impact score. Multivariable regression analysis, after adjusting for potential confounding factors, provided odds ratio (OR) and 95% confidence intervals (CI) for stoma-related problems' association with restrictions in daily life. RESULTS: The 2262 rectal cancer survivors completed the questionnaire at a median of 5.4 years (interquartile range 3.8-7.6) after stoma formation. In the total sample, leakage (58%) and troublesome odour (55%) were most prevalent followed by skin problems (27%) and pain (21%). Stoma-related problems were more prevalent in patients with parastomal bulging. A total of 431 (19%) reported feeling restricted in daily activities in life with a stoma. Leakage, odour, skin problems, stool consistency, and frequent appliance changes were significantly associated with restrictions in daily life. The highest risk of experiencing restrictions was seen for patients having odour (OR 2.74 [95% CI: 1.99-3.78]) more than once a week and skin problems (OR 1.77 [95% CI: 1.38-2.27]). CONCLUSION: In this large cohort with rectal cancer, stoma-related problems were highly prevalent and impacted daily life. Supportive care strategies should entail outreach to patients with a long-term stoma.

Oncological outcomes after complete mesocolic excision in right-sided colon cancer: a population-based study.

AIM: Complete mesocolic excision (CME) has been proposed as the preferred surgical technique for resection of colon cancer. This prospective cohort study evaluates the effect of CME surgery on colon cancer mortality after right-sided hemicolectomy on a population level. METHODS: Data from the Swedish Colorectal Cancer Registry and the Cause of Death Registry on all patients treated with elective right-sided hemicolectomy for colon cancer Stages I-III in the Stockholm County 2008-2012 were analysed. Adherence to principles of CME surgery was determined by structured analysis of anonymized surgical reports regarding the presence of five essential features. The exposure to CME was graded as group 0 (not exposed to CME), group 1 (intermediate) and group 2 (exposed to CME). RESULTS: In total, 1171 patients were analysed with 234 (20.0%) patients in CME group 0, 453 (38.7%) patients in CME group 1 and 484 (41.3%) in CME group 2. The 5-year colon cancer mortality was 20.2% in CME group 0, 13.9% in CME group 1 and 13.1% in CME group 2 (P = 0.026). The adjusted hazard ratio for colon cancer mortality was 0.61 (95% CI 0.42-0.91; P = 0.014) for CME group 1 and 0.52 (95% CI 0.35-0.77; P = 0.001) for CME group 2. DISCUSSION: The presence of predefined CME features in surgical reports was related to a graded benefit on cancer-specific mortality after right-sided hemicolectomy for colon cancer Stages I-III.

Emergency resection or diverting stoma followed by elective resection in patients with colonic obstruction due to locally advanced cancer: a national cohort study.

AIM: The aim was to assess long-term prognosis after emergency resection versus primary diverting stoma followed by elective tumour resection. METHOD: A national-register-based cohort study with retrospective analysis of prospectively collected data was performed. All Swedish patients with non-metastatic obstructive locally advanced colon cancer treated with emergency resection or diverting stoma, followed by an elective resection, between 2007 and 2017 were included. The Kaplan-Meier method and Cox proportional hazards model were used to compare all-cause mortality between patients with emergency resection and elective right- and left-sided resection. The multivariable model was adjusted for year of diagnosis, age at diagnosis, sex, Charlson Comorbidity Index, American Society of Anesthesiologists class, tumour location and pN stage. RESULTS: In all, 751 patients with a tumour in the right colon and 700 patients with a tumour in the left colon were included. Emergency resection was more common in patients with right-sided colon tumours (681/751) than in patients with left-sided colon tumours (483/700). The 5-year overall survival in patients with right-sided tumours was 25% after emergency resection and 46% after diverting stoma followed by elective resection (log-rank test P = 0.001). The corresponding numbers for patients with left-sided colon tumours were 40% and 64% (P < 0.001). Emergency resection was independently associated with increased all-cause mortality in patients with left-sided tumour (hazard ratio 1.63, 95% CI 1.21-2.19) but not in patients with right-sided tumour (hazard ratio 1.21, 95% CI 0.80-1.81). CONCLUSION: Diverting stoma followed by elective resection is associated with improved survival compared with emergency resection in patients with left-sided colonic obstruction due to locally advanced tumours.

Translation and international validation of the Colostomy Impact score.

AIM: Optimal oncological resection in cancers of the lower rectum often requires a permanent colostomy. However, in some patients a colostomy may have a negative impact on health-related quality of life (HRQoL). The Colostomy Impact (CI) score is a simple questionnaire that identifies patients with stoma dysfunction that impairs HRQoL by dividing patients into 'minor' and 'major' CI groups. This aim of this study is to evaluate construct and discriminative validity, sensitivity, specificity and reliability of the CI score internationally, making it applicable for screening and identification of patients with stoma-related impaired HRQoL. METHOD: The CI score was translated in agreement with WHO recommendations. Cross-sectional cohorts of rectal cancer survivors with a colostomy in Australia, China, Denmark, the Netherlands, Portugal, Spain and Sweden were asked to complete the CI score, the European Organization for Research and Treatment of Cancer (EORTC) quality of life 30-item core questionnaire, the stoma-specific items of the EORTC quality of life 29-item colorectal-specific questionnaire and five anchor questions assessing the impact of colostomy on HRQoL. RESULTS: A total of 2470 patients participated (response rate 51%-93%). CI scores were significantly higher in patients reporting reduced HRQoL due to their colostomy than in patients reporting no reduction. Differences in EORTC scale scores between patients with minor and major CI were significant and clinically relevant. Sensitivity was high regarding dissatisfaction with a colostomy. Regarding evaluation of discriminative validity, the CI score relevantly identified groups with differences in HRQoL. The CI score proved reliable, with equal CI scores between test and retest and an intraclass correlation coefficient in the moderate to excellent range. CONCLUSION: The CI score is internationally valid and reliable. We encourage its use in clinical practice to identify patients with stoma dysfunction who require further attention.

Endometriosis, the great imitator - a successful case of fertility preservation in a woman receiving sterilizing treatment due to a diagnosis of rectosigmoid carcinoma.

Bowels are the most common site of extrapelvic endometriosis. Still, colonic endometriosis often presents a diagnostic challenge, mimicking a broad spectrum of diseases including primary colonic malignancy. For women of fertile age, the consequences of endometriosis being misdiagnosed as colorectal cancer may include loss of fertility. We hereby present a case of endometriosis mimicking rectosigmoid adenocarcinoma in a young woman, where fertility preservation prior to the start of antineoplastic treatments turned out to be of crucial importance for the woman's future attempts to achieve a pregnancy and livebirth.

Administration of adjuvant chemotherapy for stage II-III colon cancer patients: An European population-based study.

The advantage of adjuvant chemotherapy (ACT) for treating Stage III colon cancer patients is well established and widely accepted. However, many patients with Stage III colon cancer do not receive ACT. Moreover, there are controversies around the effectiveness of ACT for Stage II patients. We investigated the administration of ACT and its association with overall survival in resected Stage II (overall and stratified by low-/high-risk) and Stage III colon cancer patients in three European countries including The Netherlands (2009-2014), Belgium (2009-2013) and Sweden (2009-2014). Hazard ratios (HR) for death were obtained by Cox regression models adjusted for potential confounders. A total of 60244 resected colon cancer patients with pathological Stages II and III were analyzed. A small proportion (range 9-24%) of Stage II and over half (range 55-68%) of Stage III patients received ACT. Administration of ACT in Stages II and III tumors decreased with higher age of patients. Administration of ACT was significantly associated with higher overall survival in high-risk Stage II patients (in The Netherlands (HR; 95%CI = 0.82 (0.67-0.99), Belgium (0.73; 0.59-0.90) and Sweden (0.58; 0.44-0.75)), and in Stage III patients (in The Netherlands (0.47; 0.43-0.50), Belgium (0.46; 0.41-0.50) and Sweden (0.48; 0.43-0.54)). In Stage III, results were consistent across subgroups including elderly patients. Our results show an association of ACT with higher survival among Stage III and high-risk Stage II colon cancer patients. Further investigations are needed on the selection criteria of Stages II and III colon cancer patients for ACT.

Management and Outcome After Multivisceral Resections in Patients with Locally Advanced Primary Colon Cancer.

BACKGROUND: Locally advanced colon cancer invading surrounding organs or structures is challenging to surgeons and oncologists. Multivisceral resections with tumor removal en bloc with invaded tissues provide the best chance for cure. OBJECTIVE: We aimed to assess the management and outcomes after multivisceral resections in patients with clinically infiltrative, locally advanced primary colon cancer. DESIGN: This is a descriptive retrospective cohort study. SETTINGS: A total of 121 consecutive patients with locally advanced primary colon cancer underwent en bloc multivisceral resections at a tertiary referral unit for colorectal cancer between 2007 and 2014. MAIN OUTCOME MEASURES: Patient demographics, surgical details, histopathological findings, and outcomes were analyzed through registry data and reviews of patient files. RESULTS: An R0 resection was achieved in 112 patients (92.6%), and an R1 resection was achieved in 9 patients (7.4%). Actual tumor cell infiltration in resected tissues was found in 77 patients (63.6%), and inflammation was found in 44 patients (36.4%). The estimated 5-year overall survival was 60.8% and 86.9%. Survival was significantly better after R0 than after R1 resections. After a median follow-up of 28 months, recurrent disease was diagnosed in 25 patients (20.7%). Female sex, low tumor stage, and adjuvant chemotherapy, but not tumor infiltration per se, were independently associated with better overall survival in a multivariate analysis. LIMITATIONS: The main limitations of the study are the retrospective design and the fact that all patients were operated on at 1 institution by a small number of surgeons. CONCLUSIONS: Patients with locally advanced colon cancer can be cured with an R0 resection. All involved surrounding tissues should be removed en bloc with the primary tumor. See Video Abstract at http://links.lww.com/DCR/A548.

Waiting times for cancer patients in Sweden: A nationwide population-based study.

AIMS: The reported long waiting times for cancer patients have mostly been related to prognostic outcome and less to patient-related experience to outcome. We assessed waiting times for patients with cancer of the breast, prostate, colon or rectum in Sweden. METHODS: The median time from referral to start of treatment was assessed using data from clinical cancer registers for patients who received curative treatment during 2011, 2012 and 2013. RESULTS: The median overall waiting time in different counties ranged from 7 to 28 days for breast cancer, from 117 to 280 days for prostate cancer, from 27 to 64 days for colon cancer and from 48 to 80 days for rectal cancer. For the entire nation, the median time from referral to start of treatment remained unchanged from 2011 to 2013 for each cancer diagnosis. CONCLUSIONS: Large variations were found in waiting times between different counties in Sweden and between different types of cancer. The long waiting times identified in this study emphasize the need to improve national programmes for more rapid diagnosis and treatment.

The loss in expectation of life after colon cancer: a population-based study.

BACKGROUND: To demonstrate how assessment of life expectancy and loss in expectation of life can be used to address a wide range of research questions of public health interest pertaining to the prognosis of cancer patients. METHODS: We identified 135,092 cases of colon adenocarcinoma diagnosed during 1961-2011 from the population-based Swedish Cancer Register. Flexible parametric survival models for relative survival were used to estimate the life expectancy and the loss in expectation of life. RESULTS: The loss in expectation of life for males aged 55 at diagnosis was 13.5 years (95 % CI 13.2-13.8) in 1965 and 12.8 (12.4-13.3) in 2005. For males aged 85 the corresponding figures were 3.21 (3.15-3.28) and 2.10 (2.04-2.17). The pattern was similar for females, but slightly greater loss in expectation of life. The loss in expectation of life is reduced given survival up to a certain time point post diagnosis. Among patients diagnosed in 2011, 945 life years could potentially be saved if the colon cancer survival among males could be brought to the same level as for females. CONCLUSION: Assessment of loss in expectation of life facilitates the understanding of the impact of cancer, both on individual and population level. Clear improvements in survival among colon cancer patients have led to a gain in life expectancy, partly due to a general increase in survival from all causes.

Risk of Venous Thromboembolic Events After Surgery for Cancer.

Importance: The risks and benefits of thromboprophylaxis therapy after cancer surgery are debated. Studies that determine thrombosis risk after cancer surgery with high accuracy are needed. Objectives: To evaluate 1-year risk of venous thromboembolic events after major cancer surgery and how these events vary over time. Design, Setting, and Participants: This register-based retrospective observational matched cohort study included data on the full population of Sweden between 1998 and 2016. All patients who underwent major surgery for cancer of the bladder, breast, colon or rectum, gynecologic organs, kidney and upper urothelial tract, lung, prostate, or gastroesophageal tract were matched in a 1:10 ratio with cancer-free members of the general population on year of birth, sex, and county of residence. Data were analyzed from February 13 to December 5, 2023. Exposure: Major surgery for cancer. Main Outcomes and Measures: The main outcome was incidence of venous thromboembolic events within 1 year after the surgery. Crude absolute risks and risk differences of events within 1 year and adjusted time-dependent cause-specific hazard ratios (HRs) of postdischarge events were calculated. Results: A total of 432 218 patients with cancer (median age, 67 years [IQR, 58-75 years]; 68.7% women) and 4 009 343 cancer-free comparators (median age, 66 years [IQR, 57-74 years]; 69.3% women) were included in the study. The crude 1-year cumulative risk of pulmonary embolism was higher among the cancer surgery population for all cancers, with the following absolute risk differences: for bladder cancer, 2.69 percentage points (95% CI, 2.33-3.05 percentage points); for breast cancer, 0.59 percentage points (95% CI 0.55-0.63 percentage points); for colorectal cancer, 1.57 percentage points (95% CI, 1.50-1.65 percentage points); for gynecologic organ cancer, 1.32 percentage points (95% CI, 1.22-1.41 percentage points); for kidney and upper urinary tract cancer, 1.38 percentage points (95% CI, 1.21-1.55 percentage points); for lung cancer, 2.61 percentage points (95% CI, 2.34-2.89 percentage points); for gastroesophageal cancer, 2.13 percentage points (95% CI, 1.89-2.38 percentage points); and for prostate cancer, 0.57 percentage points (95% CI, 0.49-0.66 percentage points). The cause-specific HR of pulmonary embolism comparing patients who underwent cancer surgery with matched comparators peaked just after discharge and generally plateaued 60 to 90 days later. At 30 days after surgery, the HR was 10 to 30 times higher than in the comparison cohort for all cancers except breast cancer (colorectal cancer: HR, 9.18 [95% CI, 8.03-10.50]; lung cancer: HR, 25.66 [95% CI, 17.41-37.84]; breast cancer: HR, 5.18 [95% CI, 4.45-6.05]). The hazards subsided but never reached the level of the comparison cohort except for prostate cancer. Similar results were observed for deep vein thrombosis. Conclusions and Relevance: This cohort study found an increased rate of venous thromboembolism associated with cancer surgery. The risk persisted for about 2 to 4 months postoperatively but varied between cancer types. The increased rate is likely explained by the underlying cancer disease and adjuvant treatments. The results highlight the need for individualized venous thromboembolism risk evaluation and prophylaxis regimens for patients undergoing different surgery for different cancers.

Stage at diagnosis and colorectal cancer survival in six high-income countries: a population-based study of patients diagnosed during 2000-2007.

BACKGROUND: Large international differences in colorectal cancer survival exist, even between countries with similar healthcare. We investigate the extent to which stage at diagnosis explains these differences. METHODS: Data from population-based cancer registries in Australia, Canada, Denmark, Norway, Sweden and the UK were analysed for 313 852 patients diagnosed with colon or rectal cancer during 2000-2007. We compared the distributions of stage at diagnosis. We estimated both stage-specific net survival and the excess hazard of death up to three years after diagnosis, using flexible parametric models on the log-cumulative excess hazard scale. RESULTS: International differences in colon and rectal cancer stage distributions were wide: Denmark showed a distribution skewed towards later-stage disease, while Australia, Norway and the UK showed high proportions of 'regional' disease. One-year colon cancer survival was 67% in the UK and ranged between 71% (Denmark) and 80% (Australia and Sweden) elsewhere. For rectal cancer, one-year survival was also low in the UK (75%), compared to 79% in Denmark and 82-84% elsewhere. International survival differences were also evident for each stage of disease, with the UK showing consistently lowest survival at one and three years. CONCLUSION: Differences in stage at diagnosis partly explain international differences in colorectal cancer survival, with a more adverse stage distribution contributing to comparatively low survival in Denmark. Differences in stage distribution could arise because of differences in diagnostic delay and awareness of symptoms, or in the thoroughness of staging procedures. Nevertheless, survival differences also exist for each stage of disease, suggesting unequal access to optimal treatment, particularly in the UK.

A machine learning tool for identifying non-metastatic colorectal cancer in primary care.

BACKGROUND: Primary health care (PHC) is often the first point of contact when diagnosing colorectal cancer (CRC). Human limitations in processing large amounts of information warrant the use of machine learning as a diagnostic prediction tool for CRC. AIM: To develop a predictive model for identifying non-metastatic CRC (NMCRC) among PHC patients using diagnostic data analysed with machine learning. DESIGN AND SETTING: A case-control study containing data on PHC visits for 542 patients >18 years old diagnosed with NMCRC in the Västra Götaland Region, Sweden, during 2011, and 2,139 matched controls. METHOD: Stochastic gradient boosting (SGB) was used to construct a model for predicting the presence of NMCRC based on diagnostic codes from PHC consultations during the year before the date of cancer diagnosis and the total number of consultations. Variables with a normalised relative influence (NRI) >1% were considered having an important contribution to the model. Risks of having NMCRC were calculated using odds ratios of marginal effects. RESULTS: Of the 361 variables used as predictors in the stochastic gradient boosting model, 184 had non-zero influence, with 16 variables having NRI >1% and a combined NRI of 63.3%. Variables representing anaemia and bleeding had a combined NRI of 27.6%. The model had a sensitivity of 73.3% and a specificity of 83.5%. Change in bowel habit had the highest odds ratios of marginal effects at 28.8. CONCLUSION: Machine learning is useful for identifying variables of importance for predicting NMCRC in PHC. Malignant diagnoses may be hidden behind benign symptoms such as haemorrhoids.

Trends in Treatment of Colorectal Cancer and Short-term Outcomes During the First Wave of the COVID-19 Pandemic in Sweden.

Importance: The COVID-19 pandemic has had a large impact on health care systems, not least the treatment of malignant diseases, including colorectal cancer. Objective: To investigate the treatment of colorectal cancer and short-term outcomes during the first wave of the COVID-19 pandemic, compared with the year before. Design, Setting, and Participants: This register-based cohort study used information from the Swedish Colorectal Cancer Registry during the years 2020 and 2019. Patients were from the Stockholm-Gotland region, 1 of 6 health care regions in Sweden, with approximately one-fifth of the country's population and 8 hospitals. All patients with a diagnosis of colorectal cancer from March 1 to August 31, 2019, and March 1 to August 31, 2020, were eligible. Data were analyzed from May to June 2021. Exposures: Diagnosis of colorectal cancer during the peak of the COVID-19 pandemic in 2020. Main Outcomes and Measures: The study aimed to compare the number of patients, time to surgery, operation methods, short-term complications, and residents' involvement in surgical practice between 2019 and 2020. Subanalyses were conducted for colon and rectal cancer. Results: A total of 1140 patients (583 men [51%]; median [IQR] age, 74 [26-99] years in 2019 and 73 [24-96] years in 2020) were enrolled. Fewer patients received a diagnosis of colorectal cancer in March through August 2020 compared with the same months in 2019 (550 vs 590 patients). Overall, patient characteristics were similar, but pretherapeutic tumor stage was more advanced in 2020 compared with 2019, with an increased proportion of T4 tumors (30% [172 patients] vs 22% [132 patients]; χ23 = 21.1; P < .001). The proportion of patients undergoing laparoscopic surgery, time to surgery, and 30-day complications were similar, but the proportion of patients treated with ostomy almost doubled between 2019 and 2020, from 17% (53 patients) to 30% (96 patients) (absolute risk, 13.0%; 95% CI, 6.8% to 20.0%). Residents participated in fewer resections in 2020 than in 2019 (35% [108 patients] vs 27% [83 patients]; absolute risk, -7.90%; 95% CI, -15.00% to -0.55%). On the other hand, the treatment and outcomes for rectal cancer were comparable between the years. Significantly more patients were transferred to the nonemergency, COVID-free hospital in the region in 2020. Conclusions and Relevance: In this Swedish register-based cohort study of patients who received a diagnosis of colorectal cancer during the most intense period of the COVID-19 pandemic, a significant increase in ostomy formation for patients with colon cancer and a lower participation of residents during surgery were observed. These changes most likely were aimed at reducing complications and intensive care unit care.

The impact of hospital volume on survival in patients with locally advanced colonic cancer.

BACKGROUND: High hospital volume has been shown associated with improved survival in patients with several cancers. The aim of this nationwide cohort study was to investigate whether hospital volume affects survival in patients with locally advanced colonic cancer. METHODS: All patients with non-metastatic locally advanced colonic cancer diagnosed between 2007 and 2017 in Sweden were included. Tertiles of annual hospital volume of locally advanced colonic cancer were analysed and 5-year overall and colonic cancer-specific survival were calculated with the Kaplan-Meier method. HRs comparing all-cause and colonic cancer-specific mortality rates were estimated using Cox models adjusted for potential confounders (age, sex, year of diagnosis, co-morbidity, elective/emergency resection, and university hospital) and mediators (preoperative multidisciplinary team assessment, neoadjuvant chemotherapy, radical resection, and surgical experience). RESULTS: A total of 5241 patients were included with a mean follow-up of 2.7-2.8 years for low- and high-volume hospitals. The number of patients older than 79 years were 569 (32.3 per cent), 495 (29.9 per cent), and 482 (26.4 per cent) for low-, medium- and high-volume hospitals respectively. The 3-year overall survival was 68 per cent, 60 per cent and 58 per cent for high-, medium- and low-volume hospitals, respectively (P < 0.001 from log rank test). High volume hospitals were associated with reduced all-cause and colon cancer-specific mortality after adjustments for potential confounders (HR 0.76, 95 per cent CI 0.62 to 0.93 and HR 0.73, 95 per cent CI 0.59 to 0.91, respectively). The effect remained after inclusion of potential mediators. CONCLUSIONS: High hospital volume is associated with reduced mortality in patients with locally advanced colonic cancer.