The influence of time period and birth cohort effects on age-specific incidence rates of pancreatic cancer (PC) and kidney cancer (KC) in white males and females was analyzed using SEER 9 data collected during 1975-2004. To estimate these effects, we used our novel approach that is applicable for any arbitrary hazard function. By utilizing the incidence rates of first primary, microscopically confirmed cases observed in six five-year time periods and 17 cohorts, we found turnovers in the PC and KC incidence rate distributions at old ages. For PC, no systematic changes were revealed in both time period and cohort coefficients during the considered time observation. For KC, however, we found systematically increasing trends for time period coefficients, while trends of birth cohort effect coefficients remain unchangeable during 1975-2004. The proposed approach can be used in the mathematical modeling of different types of carcinogenesis.