Treatment and Survival From Colorectal Cancer in Denmark, England, Norway, and Sweden: A Population-Based Study

Background: Colorectal cancer (CRC) patients in Denmark and England have historically had worse outcomes than patients diagnosed in other high-income countries with similar healthcare coverage. This survival deficit may be partly explained by differences in stage distribution due to delays in cancer diagnosis, however, differences in stage-specific survival suggest that differences in treatment also explain the survival gap. Aim: We aim to provide a comparison of stage-specific survival of CRC patients diagnosed in Denmark, England, Norway and Sweden, and compare the probability of receiving potentially curative surgery (PCS) by patient and tumor characteristics to understand whether differences in stage and treatment help explain the international differences in survival. Methods: Population-based information on patients aged 18-99 years diagnosed with primary malignant colon or rectal cancer in Denmark, England, Norway, and Sweden during 2010-2012 was extracted from national CRC registries. We compared the prevalence of PCS by stage and age category, and estimated the probability of receiving it using multivariate logistic regression. Age-standardized net survival was estimated using a multivariable modeling approach. Results: There were 13,230 patients diagnosed with CRC in Denmark, 99,869 in England, 11,754 in Norway, and 17,584 in Sweden between 2010 and 2012. The proportion of patients with missing stage information was higher in England than in the other countries. Stage distribution was otherwise similar. Survival of patients with stage I-II tumors was generally comparable between the countries, but lower in England and - to a lesser degree - in Denmark for stage III-IV disease. Patients with unknown stage had lower survival than staged patients in all countries. We found marked disadvantages in the probability of receiving PCS in older patients with stage II-IV disease in England, and stage IV colon cancer patients in Denmark. The proportion of surgically-treated rectal cancer patients (and their survival) was comparable between Denmark, Norway and Sweden for each combination of age group and stage, except for patients diagnosed with stage I disease. The proportion of patients receiving surgery and survival from rectal cancer was generally lower in England. Conclusion: Denmark seems to be catching up with Norway and Sweden, especially in rectal cancer survival. Despite recent improvements, CRC survival in England remains lower than in Sweden and Norway. Survival generally paralleled countries' relative performance in the provision of potentially curative surgery. Differences in patient selection for surgery, especially in older patients and/or with advanced disease, may partly explain the survival deficit. Increases in the proportion treated, in combination with efforts in postoperative care and with other treatment modalities, may translate into better longer-term outcomes, especially for frail patients.