Laryngeal cancer treatment and survival differences across regional cancer centres in Ontario, Canada

Abstract

Aims: We conducted a population-based study of practice patterns and outcome across the regional cancer centres providing care to patients with laryngeal cancer in the Province of Ontario, Canada.

Materials and methods: : This was a retrospective cohort study of 1547 patients with cancers of the glottic or supraglottic larynx diagnosed between 1982 and 1995. Data were collected via chart review, including: patient and disease characteristics, treatment, waiting times and treatment volumes. Vital status was obtained from the Ontario Cancer Registry. Variations across the nine regional cancer centres are described and their effect on outcome explored. All analyses were stratified by stage I and II separately from stage III and IV.

Results: Treatments differed across centres (P<0.0001); for instance, in the stage I and II group, use of a daily dose of >2.54Gy varied from 0 to 87.6% and in the stage III and IV group, total laryngectomy rates varied from a low of 6% to a high of 53%. The percentage of patients waiting more than 6 weeks from diagnosis to first treatment varied from 17 to 49% (P<0.0001). Multivariate analysis revealed cause-specific survival differences that were not explained by control for case mix, treatment or waiting times. Differences ranged from an 82% risk reduction in one centre compared with the reference (stage I and II group, P=0.008) to a 153% increase in risk (stage III and IV group, P=0.02). Centre case volumes were not associated with cause-specific survival.

Conclusions: This study quantifies the degree of variation that can occur in the treatment and outcome of people with cancer. We cannot properly assess whether care delivery is of high quality until we have a better understanding of the factors that drive such variations.