Defining the need for breast cancer radiotherapy in the general population: a criterion-based benchmarking approach

Determining the appropriate rate of radiotherapy is important for ensuring optimal radiotherapy utilisation and accessibility. A criterion-based benchmark (CBB) was developed for estimating the need for radiotherapy in incident breast cancer cases. Our primary objective was to compare an evidence-based estimate (Ebest) of need against the CBB. These estimates were then compared with radiotherapy rates in Ontario, Canada and the USA. Surgical rates were also examined.

Benchmarks were defined in Ontario as communities in proximity to cancer centres and without long waiting lists. Patient data from 1997 to 2001 were prospectively collected from radiotherapy cancer centres. Surgical data were obtained from the Canadian Institute for Health Information database. The public use file of Surveillance, Epidemiology and End Results (SEER) described treatment in the USA.

In total, 4241 cases of breast cancer were diagnosed in benchmark communities. The overall radiotherapy rate by Ebest was 64.0% (95% confidence interval: 58.1-69.8%) compared with the CBB of 60.7% (59.3-62.1%). In comparison, Ontario's overall radiotherapy rate was 55.6% (55.0-56.1%) and in SEER it was 49.3% (48.9-49.6%). Adjuvant radiotherapy rates after lumpectomy were 100% in Ebest and 83.6% (82.0-85.1%) by the CBB. The Ebest and CBB post-mastectomy rates were 21.9% (20.6-23.3%) and 34.6% (32.5-36.7%), respectively. Observed post-lumpectomy radiotherapy rates were 75.1% in Ontario and 65.3% in SEER. Post-mastectomy radiotherapy rates were 29.5% in Ontario and 17.0% in SEER.

CBB provides a reasonable estimate of the overall need for radiotherapy in breast cancer. Observed radiotherapy rates in Ontario and the USA suggest an age-related decrease in the use of radiotherapy. The benchmark estimate suggests a shortfall of adjuvant breast radiotherapy utilisation in Ontario.