After a cancer diagnosis, additional tests are used to further classify and stage the disease. These staging tests provide critical information for selecting among treatment options and also provide prognostic information (e.g., likelihood of survival). Cancer patients who have a complete set of staging tests have better survival compared to those who do not (although the reason for this is not obvious) (Lee-Feldstein et al., 1994; Mandelblatt et al., 1998).
There is significant variation in oncologists' and surgeons' use of tests for diagnosis and staging for cancer (Plawker et al., 1997), and standard diagnostic workup and staging are not performed consistently in all population groups. There is evidence suggesting that appropriate staging is completed more frequently for
Physicians use information from the diagnostic workup and staging process to formulate treatment recommendations. The treatment that patients actually receive depends on a number of factors, however, including the availability of health care resources, insurance coverage, physicians' awareness of treatment options, and patients' treatment preferences. These variations often show up as differences in the geographic distribution of cancer treatments (Ballard-Barbash et al., 1996; Farrow et al., 1992, 1996; Harlan et al., 1995; Nattinger et al., 1992; Samet et al., 1990). For example, use of breast conserving therapy ranged from 48 percent in Minnesota to 74 percent in Massachusetts (Guadagnoli et al., 1998). Rates of use of systemic chemotherapy also show wide geographic variation (Osteen and Karnell, 1994).