Malignant salivary gland tumours in Sweden 1960-1989--an epidemiological study

Epidemiological data from the Swedish Cancer Registry of new cases of malignant major and accessory salivary gland tumors in Sweden between 1960 and 1989 are presented, including the total number and the age-standardised incidence rate per 1 million population, by site and sex, I(s). An analysis of the various histopathological types of malignant salivary gland tumours in the different sublocations is also given. A comparison is made between the three 10-year periods 1960-1969, 1970-1979 and 1980-1989 regarding total number and I(s). The total number of new malignant major salivary gland tumors was 2557, representing approximately 85 new cases per year and 0.3% of all new diagnosed cancers in Sweden. In addition, approximately 25 new cases per year of malignant accessory salivary gland tumors were reported. If all malignant salivary gland tumours were considered, the most common location was found in the parotid glands with a relative frequency of 57.5%, and the next most common site was malignant accessory salivary gland tumours with 22.6%. I(s) was 10.2 for the major and 3.0 for the accessory salivary glands. No major difference between the examined 10-year periods was found concerning the relative frequency, and no statistically significant difference in I(s) was found between the examined 10-year periods, except for a statistically significant decrease in the I(s) between the time periods 1960-1969 and 1980-1989 for the multiple or unspecified malignant salivary glands from 0.5 to 1.4. A difference in the distribution of various histopathological types of malignant salivary gland tumours was observed between the different time periods. This was particularly valid for the diagnoses adenoid cystic carcinomas and mucoepidermoid carcinomas which increased in number and the diagnosis malignant salivary gland tumours of mixed type, which decreased in number during the examined time periods.