The Ontario Cancer Registry (OCR) and the Surveillance, Epidemiology and End Results (SEER) databases were used to describe temporal trends in the incidence and survival of squamous cancers of the upper aerodigestive tract (UADT) in Ontario and the US between 1984 and 2001.
Between the 1984-86 and 1999-01 periods, the age-adjusted incidence rate of all first primary cancers of the UADT decreased from 11.6 (11.2-12.0) to 8.8 (8.5-9.1) in Ontario and 13.0 (12.7-13.3) to 10.2 (10.0-10.4) in the US. Significant decreases in incidence were observed in many UADT sites but there was no significant change in the incidence of cancer of the oropharynx in either the US or Canada. Over the same period, the five-year relative survival for all UADT cancers increased from 49.2% (47.2-51.2%) to 57.1%(55.0-59.1%) in Ontario and from 48.1% (46.9-49.3%) to 52.4% (51.2-53.6%) in the US. This significant improvement in the outcome of UADT cancer was largely due to a dramatic increase in the five-year relative survival for cancers of the oropharynx from 31.1% (27.1-35.1%) to 53.6% (49.3-57.9%) in Ontario and from 35.3% (32.9-37.8%) to 51.0% (48.7-53.3%) in the US.
Smaller increases in survival were observed in cancers of the oral cavity, nasopharynx, and hypopharynx, but there was no evidence of any increase in survival for cancer of the larynx. These results are consistent with the hypothesis that there has been a major change in the etiology of cancer of the oropharynx in Canada and the US and a concomitant change in its response to therapy.
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