Glottic cancer in Ontario, Canada and the SEER areas of the United States
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We compared the management and outcome of glottic cancer in Ontario, Canada to that in the Surveillance, Epidemiology and End Results (SEER) Program areas in the United States to determine whether the greater use of primary radiotherapy with surgery reserved for salvage in Ontario was associated with similar survival and better larynx retention rates than the U.S. approach where primary surgery is used more often. Electronic, clinical and hospital data were linked to cancer registry data and supplemented by chart review where necessary. Initial treatment and survival in patients diagnosed in the SEER areas from 1988 through 1994 were compared to patients from Ontario diagnosed from 1982 through 1995. Actuarial laryngectomy rates were compared for patients over 65 at diagnosis in the two regions. Analyses were conducted over all cases and stratified by disease stage. In localized disease (T1 or T2), conservative treatment was the most common initial treatment in both regions, although total laryngectomy was used more often in SEER than Ontario (6.2% vs. 0.2%, respectively, P <.001). In advanced disease (T3 or T4), total laryngectomy was more commonly used as initial treatment in SEER (62.9% vs. 21.0% in Ontario, P < or =.001). Over all cases, the relative survival rate was 80% in Ontario at 5 years compared to 78% in SEER (P =.33). In localized disease, the relative survival rates were 4 to 5% higher in Ontario from the second year on, while in advanced disease 2 to 3% higher rates in SEER did not approach statistical significance. Actuarial laryngectomy rates at 3 years differed between the two regions, with a 4% higher rate in SEER (P =.01). In localized disease, 12.6% of Ontario patients had a laryngectomy by 3 years postdiagnosis compared to 17.9% in SEER (P =.05). In advanced disease, the rates were 63.3% and 79.2%, respectively (P =.07). There are large differences in the management of glottic cancer between the SEER areas of the U.S. and Ontario and no evidence that a policy emphasizing radiotherapy with surgery reserved for salvage is associated with worse survival. Ultimate laryngectomy rates are lower in Ontario for localized disease and may be lower for advanced disease. Conservation treatment should be used for localized disease while the treatment decision in advanced disease may be especially sensitive to patient values for voice retention versus initial cure.
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