Cancers of the upper aerodigestive tract in Ontario, Canada, and the United States

BACKGROUND. Squamous cancers of the upper aerodigestive tract (UADT) are re lated to the use of tobacco and/or alcohol, and in North America they are m ore common among the poor. They are usually locoregionally confined at diag nosis, and local treatment with surgery and/or radiation therapy is often c urative. This study compares the incidence and survival of this group of di seases in Canada and the U.S., two North American neighbors with many cultu ral similarities but significant differences in their health care and socia l programs. METHODS. To describe and compare the case mix, incidence, and outcome of sq uamous cancers of the UADT in Ontario, Canada, and the U.S., we used the On tario Cancer Registry (OCR) and the Surveillance, Epidemiology, and End Res ults (SEER) registries in the U.S. to identify all cases of cancer with int ernational Classification of Disease (ICD) codes 141, 143-9, 160-1, and a s ubset of 140, which were diagnosed between 1982 and 1994. ICD-O histology c odes were placed into clinically relevant groupings, and ICD-9 site codes w ere grouped into sites as defined by the International Union Against Cancer and the American Joint Committee on Cancer. Age-adjusted incidence rates w ere calculated for each site. For the SEER registry, race specific incidenc e rates were also calculated. Observed and expected survival were plotted b y site and registry, and from these, relative survival was calculated. Surv ival was compared during the first 5 years after diagnosis and during the n ext 5 years among patients who had survived the first 5 years. RESULTS. Of the 16,577 and 42,990 cases identified in the OCR and SEER regi stries, respectively, squamous cancer was by far the most common histology (94.1% in OCR, 94.6% in SEER) and will Form the main subject of this report . The distribution of squamous cancers by site, subsite, age, and gender we re remarkably similar in the two populations. Overall, the incidence was ab out 17% higher in the U.S. than in Ontario, and this difference was seen fo r all sites except the nasopharynx, which was more common in Ontario. The h igher incidence in the U.S. in part reflects the much higher rate for Afric an Americans than for Americans of other ethnic backgrounds. During the fir st 5 years after diagnosis, when most deaths from UADT cancer occur, there was a significant relative survival difference in favor of the U.S. for can cer of the supraglottis, and in favor of Ontario for cancer of the oral cav ity. There was a nonsignificant trend in favor of Ontario for cancer of the nasopharynx Within the SEER population, for all sites except the nasophary nx, 5-year relative surival was considerably worse for African Americans th an for Americans of other ethnic backgrounds. Examination of survival beyon d 5 years after diagnosis for patients who had survived the first 5 years r evealed that for all sites, the observed survival continued to diverge mark edly from the expected survival. The excess mortality ranged from less than 20% for glottic and nasopharyngeal cancers to about 30-40% for oropharynge al and supraglottic cancers. CONCLUSIONS. Despite remarkable similarities in case mix between the two co untries, UADT cancers were more frequent in the SEER population of the U.S. than in Ontario, and this was partly attributable to the much higher incid ence among African Americans. Significant differences between the registrie s in 5-year survival were seen for several sites. African Americans with UA DT cancers had much worse prognoses than did Americans of other ethnic back grounds. Patients who survive their UADT cancer remain at a higher-than-exp ected risk of death even after they have been cured. (C) 2000 American Canc er Society.