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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.: 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.Treatments differed across centres (P0.0001); for instance, in the stage I and II group, use of a daily dose of2.54Gy 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% (P0.0001). 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.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.

Aims : To describe the variation in the delivery of radiation therapy to patients with T1N0 glottic cancer who were diagnosed in Ontario, Canada, between 1982 and 1995. Materials and Methods : The patient population consisted of a random sample of 461 patients treated with curative intent from the nine cancer centres that administer radiation therapy in the province. Abstracted variables included prescribed dose (Gy) and fractionation (f), beam energy and arrangement, set-up, field size, beam modifiers, positioning and treatment interruptions. Results : Thirteen prescribed dose-fractionation schemes (≥four cases each) were identified, including 50.0–53.0Gy/20f (54.5%), 55.0–61.0Gy/25f (30.3%), and 60.0–66.0Gy/30–33f (7.7%). All regimens used one fraction per day, 5 days per week. An isocentric set-up was used (94.3%), with megavoltage (MV) beam energies of Cobalt-60 (87.9%), 6MV (6.1%) and 4MV (6.1%). A lateral parallel-opposed pair of beams was the predominant technique (76.4%) versus an anterior oblique pair (17.2%) or angle-down pair (caudally directed fields to achieve shoulder clearance, 5.7%). Wedging (96.3%) and bolus (11.8%) were used as beam-modifying devices. Predominant field-width dimensions were 5.0–6.0cm (43.4%) and 6.5–7.0cm (43.1%), and field length dimensions were 5.0–6.0cm (49.5%) and 6.5–7.0cm (35.0%). Head, neck or chin immobilisation was used in 86.9% of the cases, with 94.6% of these being custom-made. We found that radiotherapy practice was stable over time, except for a trend of increasing field size and increasing use of immobilisation. In contrast, we found practice variations among the province's cancer centres. On the basis of our findings, we defined a predominant technical practice consisting of Cobalt-60 (reflecting machine availability during the period of the study), an isocentric set-up, a lateral parallel-opposed pair technique with wedging, and supine-head neutral positioning with custom immobilisation. Forty-two per cent of the cases had one or more components of treatment that differed from this definition. Conclusions : Description of practice variation can provoke discussion about unrecognised differences in practice policies, perhaps identifying the need for better evidence, treatment guidelines, or both.