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Posters Sessions

Central Cancer Registry

Brain Cancer Survival in North Carolina

1990-1995 Reported Brain Cancer Cases
Followed up through December 31, 1997

An award-winning poster session
By Bob Allis
North Carolina Central Cancer Registry
State Center for Health Statistics

for the 1999 Annual Meeting
North American Association of Central Cancer Registries

Table of Contents

  • Abstract
  • The legislation in North Carolina requires the collection of follow-up data by the Central Cancer Registry. This study compares the passive follow-up method to the active follow-up method that requires many more resources.

    This study examines the survival rates among brain cancer patients in North Carolina from the period of 1990 through 1995. Follow-up of these patients is carried through 1997. There were 2778 cases of brain cancer in that period of time. The results are to be compared with SEER data to check for reliability of the data and to determine the effectiveness of passive follow-up.

  • Introduction
  • The SEER program provides active follow-up on all living patients of cancer except those with in situ cancer of the cervix uteri. This method requires a great deal of resources.

    Many Cancer Registries do not have sufficient resources to conduct active follow-up on patients. The aim of this study is to see whether the passive method of follow-up yields similar and reliable results to those using more resource-intensive methods.

    A survival analysis is an ideal tool to measure this, since it depends on current vital status and information about each patient.

  • Methods
    • Brain Cancer incidence data from 1990 through 1995 were used for analysis, yielding 2778 cases (after removal of duplicates).
    • Cases were tracked through the end of 1997.
    • The cases were matched against the 1990-1997 NC Death File by social security number, first name, last name, race, gender and date of birth.
    • The underlying cause of death was restricted to neoplasms of the brain: ICD-9 codes 191.x and 239.6.
    • The Life Table approach was used to estimate the observed survival rates. The reported SEER rates are the relative survival rates, in which the observed survival rate is adjusted for expected mortality.
    • The relative rate is always larger than the "observed" rate.
  • Results
    • Graph of Three Year Survival of Brain Cancer
      Graph of Three Year Survival of Brain Cancer
    • The differences between SEER rates (using active follow-up) and the North Carolina rates (passive follow-up) were not significantly different. An interesting note, however, is that 1-year NC rates were higher than SEER but 2-year (and beyond) NC rates were lower than SEER rates.

      Tables of Rate Differences
    • Observed Survival Rates (NCCCR)
        1990 1991 1992 1993 1994 1995
      1 year 57.1 57.9 59.3 60.7 56.2 57.8
      2 year 34.3 35.0 36.5 34.7 36.3  
      3 year 28.1 30.2 31.8 26.1    
      4 year 23.4 26.7 26.7      
      5 year 21.0 22.0        
      6 year 18.1          

      Relative Survival Rates (SEER)
        1989 1990 1991 1992 1993 1994
      1 year 52.4 54.1 54.4 52.4 53.1 53.1
      2 year 37.5 37.7 40.0 39.0 38.3  
      3 year 33.0 32.6 36.5 34.7    
      4 year 30.0 30.8 34.7      
      5 year 28.8 29.3        
      6 year 27.8          
    • Patients who received care at the state's Comprehensive Cancer Centers had a higher survival rate than at any other types of hospitals - which implies better quality of care leads to better chance for survival.

      Graph of Differences between Hospital Type
      Graph of Differences between Hospital Type
      ACoS Approved: American College of Surgeons accredited facilities
    • Survival rates in rural areas were found to be higher than survival rates in urban areas.

      Graph of Urban versus Rural Survival Rates
      Graph of Urban versus Rural Survival Rates
    • Survival rates by age follow the same pattern as SEER rates: the patients diagnosed at a younger age (<45) have a much higher survival rate.

      Graph of Survival Rates by Age of Diagnosis
      Graph of Survival Rates by Age of Diagnosis
    • Rates of Survival categorized by Race and Sex also follow the same pattern as SEER rates, where African-American males had a substantially higher survival rate than all other race/sex groups. A possible explanation may be that competing factors of death may drive up the survival from brain cancer in this group.

      Graph of Survival by Race and Sex
      Graph of Survival by Race and Sex
  • Conclusions
    • Passive follow-up does a good job of mirroring the results of the active follow-up method in the case of brain cancer. Since brain cancer is often quickly fatal, the chances should be better that the passive method would be successful in this case than in less fatal cancers.
    • While consistent with SEER rates, the question of the difference of survival rates between African-American males and the other race/gender groups is puzzling.
    • The differences shown in the observed survival rates in the graphs are not necessarily completely caused by any single factor. The behaviors exhibited may be due to overlapping multiple causes outside this study.
    • This study provides an excellent opportunity for further research on brain cancer survival, such as isolating those factors that cause any differences in survival rates.