Clinical Outcomes at Fox Chase Cancer Center: A Note on the Methodology

Methods and Limitations for the NCDB Survival Data

All data presented in the survival curves, or clinical outcomes charts, on these web pages are derived from the National Cancer Data Base (NCDB), a resource maintained by the American College of Surgeons.  The information below, based on the NCDB Survival Reports User Help Sheet¹, outlines the methods and limitations associated with the NCDB data.

Five-year survival curves from NCDB Survival Reports

The survival curves presented here provide overall survival estimates for selected cancer sites at 1, 2, 3, 4 and 5 years from date of diagnosis. The curves show the percent of the group alive at these different time points.  There is a separate chart for each stage of disease.  Stage was classified using the American Joint Committee on Cancer (AJCC) combined stage group (5th edition).  Reports were run separately for Fox Chase Cancer Center, community cancer centers, and comprehensive community cancer centers.  The NCDB survival reports provided the methods for generating the curves and the definition of center type. 

Case selection

Cases were diagnosed from 1998-2002. At the time the survival curves displayed here were generated, 2002 was the most recent year available with five-year follow-up information (vital status and date of last contact or date of death).  As described by the NCDB survival report manual, cases are limited to adult patients with only one diagnosis of cancer who have received all or part of their first course of therapy at Fox Chase Cancer Center or the relevant hospital from the NCDB.  As many patients treated at Fox Chase Cancer Center receive second-line therapy after primary treatment elsewhere, the total number of patients treated at Fox Chase Cancer Center for each type of cancer is generally substantially larger than the numbers presented here.  Other exclusions include unknown AJCC stage of disease and incomplete vital status information. Cases from hospitals without current accreditation from the Commission on Cancer (CoC)² are excluded.

Methods and Limitations

The five-year observed survival rates are estimated using the actuarial method with one-month intervals.  The endpoint is death from any cause (not cancer specific death); patients may have died from causes unrelated to their cancer.  Calculations were performed using the NCDB Survival Reports software tool.

The figures present unadjusted outcomes.  That is, we did not account for demographic differences (e.g., age at diagnosis, gender, socioeconomic status, insurance status), prognostic factors, and comorbidities between Fox Chase Cancer Center and other hospitals.  Also, we did not account for subjective differences in staging practices among hospitals.  For example, it is possible that a cancer considered Stage I at one hospital might be considered Stage II at another hospital due to practice patterns.  The outcomes comparisons presented here might have differed if we had accounted for such demographic and staging differences in our analyses.

¹ The full NCDB Survival Reports User Help Sheet is available at http://www.facs.org/cancer/ncdb/survivalreportuser.pdf.

² The Commission on Cancer is a program of the American College of Surgeons.