T accompanied by much speculation reg.irding the etiology of the disease. This paper indicate, the changes i n the male and female lung cancer death rates in hlassachusetts that have occLiri cd since 1906 and their apparent relationship to cigarette sinoking.
TRFNLE
In the construction of long-term trends, n u ~i ~c r o u s obstacles had to be overcome. Iri Massachusetts, prior to 1931, deaths caused by neoplasms of the lung, pleura, bronchus, and trachea were combined with a miscellaneous group of causes of death and classified as "cancer of other or unspecified organs." From 1931 to 1939, the fourth revision of the Manucil of tlrc Interircrtional List of Caiiscs of 1)etrtlr was used in Massachusetts. I n that edition, cancer of the respiratory system was divided into that of larynx, lung and pleura, and others. TIIC fifth revision of the Mnnual was first used in Massachusetts in 1940, and it separated cancer ol' the respiratory system into that ol larynx, trachea, bronchus, lung, pleura, nietliastinuin, and unspecified sites. T h e Sixth K(:ilisioii of the Iiiterntitional Lists of Diseases c i ~d C N U S ~S of L)cwtl/, first ~ised i n 1949, c o m bined the four respiratory sites untlcr two classifications: inalignant neoplasms of the trachea, bronchus, lung, and pleura, specified xnwtling to primary or secondary. Furthermore, the Sixtli I<evi.siora used a different iiicthotl ol c1;issilying the priority when multil'le causes of death were given. This resulted in a lower I-ec.orded death rate for cancer of inany sites, including that for the lung.
Since the data were not comparably classified, it was necessary to utilize several different procedures in order to coiripute trends for the period of 1906 to 1953. T h e original Massadiusctts death records for 1950 were classified by the fifth revision and compared with the data classified under the sixth revision. This mide possible the coniputation of correction From the Division o f C:anccr a n d Chronic Disease, hlassacliusctts I ~e p a r t m e n t of 1'ui)Iic Hcalth,