Gandini, Botteri, Iodice, Boniol, Lowenfels, Maisonneuve, and Boyle look at what association exists between smoking cigarettes and lung, oral cavity, pharynx, pancreas, urinary bladder, renal pelvis and urethra cancers. They also look at whether certain associations observed between cigarette smoking and these cancers vary based on the population being studied, the level of exposure being utilized, the definition of disease being used among many other factors. They conducted a systematic meta-analysis of studies conducted, which looked at cancer and cigarette smoking from 1961-2003. The cancers they looked at were utilized because of the International Agency for Research on Cancer (IRAC) knew these specific cancers could be connected to tobacco utilization. The overall results showed that the relative risks for respiratory cancers were higher than other relative risks for other cancers affecting other sites of the body.