Trends in the incidence of lip, oral, and pharyngeal cancer: Connecticut, 1935-94.

Using Connecticut Tumor Registry data we explored trends in age-adjusted (AARs) and age-specific (ASRs) incidence rates for lip, oral, and pharyngeal cancer over the 60-year period 1935-94. Particular attention was given to findings from the most recent series of 5-year periods that have not been previously analyzed. There was a long-term decline in lip cancer AARs by period, and ASRs generally fell over time and with successive birth cohorts. This notable decrease in rates continued through 1990-94 and with the more recent cohorts, particularly among males. Oral cancer AARs for males peaked in the early 1960s and the late 1970s while rates for pharyngeal cancer increased into the late 1970s. For each of these sites, rates began to decline in 1980-84 and have continued to fall into the first half of the 1990s. Among females AARs for oral and pharyngeal cancer increased more than threefold between 1935-39 and 1980-84; however, encouragingly, and in sharp contrast to the earlier trend, rates fell during the most recent 10-year period. ASRs for oral and pharyngeal cancer were increasing by the birth cohort of 1900 and tended to increase through the cohort of 1920 for males and the cohorts of 1920-30 for females. ASRs for subsequent cohorts have remained relatively unchanged or decreased modestly. It is doubtful that the observed trends in lip, oral and pharyngeal cancer incidence are primarily artifactual, but more likely represent secular changes in exposure to environmental risk factors.