Improvement in colorectal cancer survival: A population-based study
Introduction
With some 36 000 incident cases in France each year, colorectal cancer is the second most common cancer in women and the third most common in men [1]. Prognosis remains poor, but improvement in survival has been reported recently in some European countries 2, 3, 4, 5 and in the United States of America (USA) [6]. Improved diagnostic procedures, earlier diagnosis and improved therapeutic procedures have been suggested to explain survival trends 2, 4, 5, 7. Community-based studies including all cases diagnosed in a well-defined population represent the only feasible approach for assessing real improvement in prognosis in non-selected series. Such studies are rare, because they require accurate and detailed data collection, which is seldom available from general cancer registries. Two recent population-based studies have reported important changes in the management of rectal cancer with improvement in survival 4, 5. We have demonstrated previously how reduced operative mortality plays a major role in the improvement of overall survival after curative surgery [8]. The purpose of this project was to study colorectal survival trends over a 24-year period in a well-defined French population in order to explore the reasons for improvement in survival, over and above the impact of reduced operative mortality.
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Patients
A population-based registry for digestive tract cancers was established in the Côte d’Or administrative area (Burgundy, France) in 1976. It covers a resident population of 506 800 inhabitants, according to the 1999 census. Information on new cases is collected from public and private pathology laboratories, university and local hospitals, the regional cancer institute, private surgeons, oncologists and gastroenterologists, general practitioners and death certificates. No cases were registered
Trends in overall survival
Median overall survival increased from 16.4 months for patients diagnosed during 1976–1979 to 40.5 months for 1988–1991 and has remained almost stable since then for patients diagnosed up to 1999. The 5-year relative survival rate increased from 37.8% (1976–1979) to 53.4% (1988–1991) and was 52.1% for 1996–1999. The corresponding relative survival curves by period of diagnosis (Fig. 1) confirm the progressive improvement in prognosis up to 1991 with little subsequent change.
Operative mortality
Discussion
Colorectal cancer survival increased dramatically over the 24-year period between 1976 and 1999 in France. The aim of this population-based study was to explore the reasons for this improvement. Whereas results from specialised centres may be misleading due to referral bias, cancer registries allow the analysis of true epidemiological trends. Cancer survival improvement may be related to progress in diagnostic or therapeutic procedures. We have shown in a previous study that reduced operative
Conflict of interest statement
None declared.
Acknowledgements
We thank Professor Michel Coleman and Dr. Bernard Rachet from the Cancer and Public Health Unit at London School of Hygiene and Tropical Medicine, London, United Kingdom, for their help and advice.
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