The effects of short-course preoperative irradiation on local recurrence rate and survival in rectal cancer: a population-based nationwide study.

BACKGROUND

Preoperative irradiation with 5 × 5 Gy in randomized trials reduces local recurrence rate and may improve survival in patients with resectable rectal cancer.

OBJECTIVE

The aim of this study was to determine whether the same favorable effects could be observed in a population-based study.

DESIGN

This study was conducted via a retrospective analysis of prospectively collected data from the Swedish Rectal Cancer Registry.

SETTINGS

This study examined population-based data from Sweden.

PATIENTS

All newly diagnosed rectal cancers in Sweden are reported to the Swedish Rectal Cancer Registry.

INTERVENTIONS

Between 1995 and 2001, 6878 patients (stages I-III) were operated on with an anterior resection, an abdominoperineal resection, or a Hartmann's procedure. Short-course irradiation was given to 41% of patients preoperatively. To reduce bias, patients operated on with a Hartmann procedure or older than 75 years were excluded when 5-year survival was analyzed (n = 3466). Tumors were analyzed according to height (0-5 cm, 6-10 cm, 11-15 cm).

MAIN OUTCOME MEASURES

Five-year cumulative local recurrence and survival rates.

RESULTS

The 5-year cumulative local recurrence rate was 6.3% (95% CI 5.4-7.4) for patients receiving preoperative irradiation and 12.1% (95% CI 10.8-13.5) for patients not receiving preoperative irradiation. Multivariate analyses indicated the risk of local recurrence was 50% lower for patients receiving preoperative irradiation compared with patients not receiving irradiation (hazard ratio = 0.50; 95% CI 0.40-0.62). Among patients younger than 76 years and operated on with an anterior resection or abdominoperineal resection, the 5-year cumulative survival rate was 0.70 (95% CI 0.69-0.72). Disease-free and overall survivals were higher in irradiated patients, and the difference was statistically significant in low tumors.

CONCLUSIONS

In this population-based analysis, the favorable effect of preoperative short-course irradiation on local recurrence rates, seen in randomized trials, was confirmed for the entire Swedish population irrespective of tumor height and stage. Data also suggested an effect on 5-year survival, especially in patients with low tumors (0-5 cm).