Trends in rectal cancer survival in relation to the local control strategy

Abstract

13536 Background: The Swedish Rectal Cancer Trial showed improved survival with improved local control due to adjuvant radiotherapy. Improved survival in several population-based studies, credited to improved local control due to quality assurance programs involving surgery, ± radiotherapy, has also been reported. In Manitoba (Canada) local control in rectal cancer was suboptimal in the mid 1990’s (local recurrence >18% in stage I-III) despite adopting the 1991 NIH chemo-radiotherapy guidelines. There continues to be no quality assurance program. We were interested in exploring trends in survival in Manitoba, particularly in the subset of patients where local control is an issue. Methods: All patients diagnosed with rectum and rectosigmoid adenocarcinoma from 1985 to 1999 were identified from the Manitoba Cancer Registry. Demographic, peri-operative and operative treatment information, and death dates were abstracted from the Registry. Manitoba population and death counts used in the calculation of age-specific relative survival probabilities were obtained from Statistics Canada. Survival was examined for all patients for the time periods of 1985–89, 1990–94 and 1995–99 and subsequently limited to those that underwent major rectal cancer surgery (Hartmann’s, anterior, and abdominal perineal resection). The Ederer II method was used in the estimation of survival probabilities. Results: A total of 3021 rectal cancer patients were identified with 1723 (57.0%) having major surgery. Five-year relative survival for all patients was 48.7%, 49.6% and 56.2% for the three periods respectively. The major surgery group results were 56.9%, 58.1% and 59.7%. Peri-operative radiotherapy was used in 38% of the 1995–99 major surgery group, twice the rate of 1985–89; peri-operative chemotherapy 41%, a ten-fold increase. Conclusions: Consistent with other studies, overall rectal cancer five-year survival in Manitoba has improved since 1985. Smaller survival improvements in the major surgery subgroup, despite increased radiotherapy use (as well as chemotherapy), suggests that better local control was not the major factor in the overall survival improvement, as has been suggested in other studies. Future work should include review of the local control strategy and factors to explain the improved survival. No significant financial relationships to disclose.