NIOSH investigators decided to conduct a cohort incidence study of the steelworkers. Follow-up would be conducted by mailed questionnaire, to either the cohort member himself or his next of kin. The questionnaire would ask about cancer incidence, polyps incidence (possibly also associated with exposure), smoking, and drinking. Two questionnaires would be mailed. If there were no response to the mailed questionnaires, phone calls would be made.
The medical records of all decedents would be sought as an additional source of information regarding larynx cancer incidence. Medical confirmation of any self-reported larynx cancers would also be sought.
Investigators determined that the most complete and oldest data on age-specific laryngeal cancer incidence existed for the state of Connecticut, which had rates from 1935 to 1979. New York had rates available exclusive of New York City from 1950 to 1972. There were no complete national rates, but national surveys had been done for a sample of the country during three National Cancer Surveys (1938, 1948, 1970) and during two later SEER (Surveillance, Epidemiology, and End Results) surveys (1973-1977, and 1978-1981). These various surveys generally covered about 10% of the U.S. population and were considered representative. None of the cancer incidence data were broken down by smoking habits.
After considering the above, try and answer the following questions: