The impact of National Death Index linkages on population-based cancer survival rates in the United States.

BACKGROUND: In order to ensure accurate survival estimates, population-based cancer registries must ascertain all, or nearly all, patients diagnosed with cancer in their catchment area, and obtain complete follow-up information on all deaths that occurred among registered cancer patients. In the US, linkage with state death records may not be sufficient to ascertain all deaths. Since 1979, all state vital statistics offices have reported their death certificate information to the National Death Index (NDI). OBJECTIVE: This study was designed to measure the impact of linkage with the NDI on population-based relative and cancer cause-specific survival rates in the US. METHODS: Central cancer registry records for patients diagnosed 1993-1995 from California, Colorado, and Idaho were linked with death certificate information (deaths 1993-2004) from their individual state vital statistics offices and with the NDI. Two databases were created: one contained incident records with deceased patients linked only to state death records and the second database contained incident records with deceased patients linked to both state death records and the NDI. Survival estimates and 95% confidence intervals from each database were compared by state and primary site category. RESULTS: At 60 months follow-up, 42.1-48.1% of incident records linked with state death records and an additional 0.7-3.4% of records linked with the NDI. Survival point estimates from the analysis without NDI were not contained within the corresponding 95% CIs from the NDI augmented analysis for all sites combined and colorectal, pancreas, lung and bronchus, breast, prostate, non-Hodgkin lymphoma, and Kaposi sarcoma cases in all 3 states using relative survival methods. Additional combinations of state and primary site had significant survival estimate differences, which differed by method (relative versus cause-specific survival). CONCLUSION: To ensure accurate population-based cancer survival rates, linkage with the National Death Index to ascertain out of state and late registered deaths is a necessary process for US central cancer registries.

Impact of using multiple causes of death codes to compute site-specific, death certificate-based cancer mortality statistics in the United States.

BACKGROUND: Cancer mortality statistics, an important indicator for monitoring cancer burden, are traditionally restricted to instances when cancer is determined to be the underlying cause of death (UCD) based on information recorded on standard certificates of death. This study's objective was to determine the impact of using multiple causes of death codes to compute site-specific cancer mortality statistics. METHODS: The state cancer registries of California, Colorado and Idaho provided linked cancer registry and death certificate data for individuals who died between 2002 and 2004, had at least one cancer listed on their death certificate and were diagnosed with cancer between 1993 and 2004. These linked data were used to calculate the site-specific proportion of cancers not selected as the UCD (non-UCD) among all cancer-related deaths (any mention on the death certificate). In addition, the retrospective concordance between the death certificate and the population-based cancer registry, measured as confirmations rates, was calculated for deaths with cancer as the UCD, as a non-UCD, and for any mention. RESULTS: Overall, non-UCD deaths comprised 9.5 percent of total deaths; 11 of the 79 cancer sites had proportions greater than 3 standard deviations from 9.5 percent. The confirmation rates for UCD and for any mention did not differ significantly for any of the cancer sites. CONCLUSION AND IMPACT: The site-specific variation in proportions and rates suggests that for a few cancer sites, death rates might be computed for both UCD and any mention of the cancer site on the death certificate. Nevertheless, this study provides evidence that, in general, restricting to UCD deaths will not under report cancer mortality statistics.

Effect of misclassified underlying cause of death on survival estimates of colon and rectal cancer.

Inaccurate coding of patients' Underlying Cause of Death (UCOD) has constrained cause-specific survival estimates for colon and rectal cancers. Using California data from the Accuracy of Cancer Mortality study, we compared the cancer site data from the California Cancer Registry (CCR) with UCODs reported on death certificates and reclassified the UCODs based on cancer registry data when they disagreed. We then calculated 1-, 3-, 5-, and 10-year cause-specific survival for colon and rectal cancers separately, before and after the reclassification. Records from 26 312 colon and 10 687 rectal cancer patients were examined. UCOD records disagreed with CCR records for 700 (6%) of 11 404 colon cancer deaths and with 1958 (39%) of 5011 rectal cancer deaths, and 82% of the misclassified rectal cancer deaths were coded as colon cancer deaths in the UCOD. Reclassification decreased cause-specific survival for both colon and rectal cancers, but the impact was more pronounced for rectal cancer (eg, 5-year cause-specific survival of colon cancer decreased by 2.8% and of rectal cancer decreased by 20.0% relative to previous estimates; absolute rates changed from 65.4% to 63.6%, and 81.2% to 64.9%, respectively, after reclassification). Interchangeable use of the terms colon cancer and colorectal cancer is likely to be one of the reasons for UCOD misclassification. Educational measures could improve the accuracy of UCOD for colon and rectal cancer deaths.

The accuracy of cancer mortality statistics based on death certificates in the United States.

BACKGROUND: One measure of the accuracy of cancer mortality statistics is the concordance between cancer defined as the underlying cause of death from death certificates and cancer diagnoses recorded in central, population-based cancer registries. Previous studies of such concordance are outdated. OBJECTIVE: To characterize the accuracy of cancer mortality statistics from the concordance between cancer cause of death and primary cancer site at diagnosis. DESIGN: Central cancer registry records from California, Colorado, and Idaho in the U.S. were linked with state vital statistics data and evaluated by demographic and tumor information across 79 site categories. A retrospective arm (confirmation rate per 100 deaths) compared death certificate data from 2002 to 2004 with cancer registry diagnoses from 1993 to 2004, while a prospective arm (detection rate per 100 deaths) compared cancer registry diagnoses from 1993 to 1995 with death certificate data from 1993 to 2004 by International Statistical Classification of Diseases and Related Health Problems (ICD) version used to code deaths. RESULTS: With n=265,863 deaths where cancer was recorded as the underlying cause based on the death certificate, the overall confirmation rate for ICD-10 was 82.8% (95% confidence interval [CI], 82.6-83.0%), the overall detection rate for ICD-10 was 81.0% (95% CI, 80.4-81.6%), and the overall detection rate for ICD-9 was 85.0% (95% CI, 84.8-85.2%). These rates varied across primary sites, where some rates were <50%, some were 95% or greater, and notable differences between confirmation and detection rates were observed. CONCLUSIONS: Important unique information on the quality of cancer mortality data obtained from death certificates is provided. In addition, information is provided for future studies of the concordance of primary cancer site between population-based cancer registry data and data from death certificates, particularly underlying causes of death coded in ICD-10.

Does socioeconomic disparity in cancer incidence vary across racial/ethnic groups?

OBJECTIVE: Very few studies have simultaneously examined incidence of the leading cancers in relation to socioeconomic status (SES) and race/ethnicity in populations including Hispanics and Asians. This study aims to describe SES disparity in cancer incidence within each of four major racial/ethnic groups (non-Hispanic white, black, Hispanic, and Asian/Pacific Islander) for five major cancer sites, including female breast cancer, colorectal cancer, cervical cancer, lung cancer, and prostate cancer. METHODS: Invasive cancers of the five major sites diagnosed from 1998 to 2002 (n = 376,158) in California were included in the study. Composite area-based SES measures were used to quantify SES level and to calculate cancer incidence rates stratified by SES. Relative index of inequality (RII) was generated to measure SES gradient of cancer incidence within each racial/ethnic group. RESULTS: Significant variations were detected in SES disparities across the racial/ethnic groups for all five major cancer sites. Female breast cancer and prostate cancer incidence increased with increased SES in all groups, with the trend strongest among Hispanics. Incidence of cervical cancer increased with decreased SES, with the largest gradient among non-Hispanic white women. Lung cancer incidence increased with decreased SES with the exception of Hispanic men and women, for whom SES gradient was in the opposite direction. For colorectal cancer, higher incidence was associated with lower SES in non-Hispanic whites but with higher SES in Hispanics and Asian/Pacific Islander women. CONCLUSIONS: Examining SES disparity stratified by race/ethnicity enhances our understanding of the complex relationships between cancer incidence, SES, and race/ethnicity.

Racial and social class gradients in life expectancy in contemporary California.

Life expectancy, or the estimated average age of death, is among the most basic measures of a population's health. However, monitoring differences in life expectancy among sociodemographically defined populations has been challenging, at least in the United States (US), because death certification does not include collection of markers of socioeconomic status (SES). In order to understand how SES and race/ethnicity independently and jointly affected overall health in a contemporary US population, we assigned a small-area-based measure of SES to all 689,036 deaths occurring in California during a three-year period (1999-2001) overlapping the most recent US census. Residence at death was geocoded to the smallest census area available (block group) and assigned to a quintile of a multifactorial SES index. We constructed life tables using mortality rates calculated by age, sex, race/ethnicity and neighborhood SES quintile, and produced corresponding life expectancy estimates. We found a 19.6 (+/-0.6) year gap in life expectancy between the sociodemographic groups with the longest life expectancy (highest SES quintile of Asian females; 84.9 years) and the shortest (lowest SES quintile of African-American males; 65.3 years). A positive SES gradient in life expectancy was observed among whites and African-Americans but not Hispanics or Asians. Age-specific mortality disparities varied among groups. Race/ethnicity and neighborhood SES had substantial and independent influences on life expectancy, underscoring the importance of monitoring health outcomes simultaneously by these factors. African-American males living in the poorest 20% of California neighborhoods had life expectancy comparable to that reported for males living in developing countries. Neighborhood SES represents a readily-available metric for ongoing surveillance of health disparities in the US.

The impact of patient follow-up on population-based survival rates.

OBJECTIVE: This study was designed to measure the impact of variation in patient follow-up on survival statistics. METHODS: surveillance, epidemiology and end results (SEER) data were used to construct four additional datasets. These datasets simulated scenarios of complete, incomplete, and no follow-up of live patients; and complete and incomplete death ascertainment. Sixty-month observed survival proportions were calculated using the actual SEER data and the four additional datasets. RESULTS: The 60-month observed survival proportion increased from 54.44% under the original SEER dataset to 54.62% under complete ascertainment of deaths with no follow-up among live patients. Under complete death ascertainment, randomly imputing loss to follow-up among 20% of live cases resulted in a 1%-2% decrease in 60-month observed survival for 71 of the 102 SEER site categories. With follow-up limited to ascertainment of deaths, randomly missing 6% of deaths resulted in a 1% or greater increase in 60-month observed survival for 99 SEER site categories. CONCLUSIONS: This study provides evidence to support the importance of complete death ascertainment for producing accurate cancer survival statistics, and that ascertainment of deaths only should generally be sufficient for survival analysis.

Benefit of postoperative adjuvant therapy for pancreatic cancer: A population-based analysis.

BACKGROUND: Despite the recent completion of several trials of adjuvant therapy after resection for pancreatic adenocarcinoma, the absolute impact on survival and the identification of appropriate patients for treatment has remained controversial. In the current study, the authors sought to identify the impact of adjuvant therapy and factors associated with any improvement in survival after resection of pancreatic cancer. METHODS: Through the California Cancer Registry, all California residents diagnosed with pancreatic cancer between 1994 and 2002 were identified. Factors potentially impacting survival were analyzed, including patient demographics, tumor characteristics, and treatment provided. Univariate and multivariate survival analyses were performed by Kaplan-Meier and Cox regression methods. RESULTS: A total of 26,518 patients were identified; 3196 (12.1%) underwent resection as their primary treatment. The median overall survival was 16 months for patients who underwent resection. Prognostic factors associated with better survival included negative lymph node status, well-differentiated tumors, younger age, female sex, and the receipt of any adjuvant therapy. On multivariate analysis, adjuvant therapy demonstrated a statistically significant, although modest, impact on survival, with a hazards ratio of 0.79 (95% confidence interval, 0.72-0.87; P < .001). The benefit of adjuvant therapy was only apparent in those patients with lymph node-positive or poorly differentiated tumors. CONCLUSIONS: Adjuvant therapy provided for a modest improvement in overall survival after surgical resection of pancreatic cancer. The absolute effect was most pronounced in those patients with poor prognostic indicators. To identify effective systemic therapy for this deadly cancer, future clinical trials of adjuvant therapy should focus on these groups of patients.

Differences in prognostic factors and survival among White men and Black men with prostate cancer, California, 1995-2004.

The authors conducted a study to determine whether differences in prostate cancer survival between White men and Black men are reduced or eliminated after accounting for differences in prognostic factors. Using population-based statewide cancer registry data, the authors analyzed data from a cohort of 122,375 non-Hispanic White men and Black men from California who were newly diagnosed with prostate cancer between 1995 and 2004 and followed through 2004. Compared with White men, Black men were characterized by younger age at diagnosis, more distant stage, less treatment with surgery or radiation therapy, higher tumor grades, lower neighborhood socioeconomic status, and more recent year of diagnosis. Adjusted only for age, the hazard ratio for prostate cancer death (Blacks vs. Whites) was 1.61 (95% confidence interval (CI): 1.50, 1.72). Additional adjustment for potentially modifiable factors (stage and treatment) eliminated most of the racial difference in survival (adjusted hazard ratio = 1.10, 95% CI: 1.03, 1.18). The racial difference in survival was completely eliminated after further adjustment for other factors (grade, socioeconomic status, and year of diagnosis) (adjusted hazard ratio = 0.99, 95% CI: 0.92, 1.06). Thus, the large difference in prostate cancer survival between White men and Black men was completely explained by known prognostic factors, with potentially modifiable disparities playing the largest role.

Survival among patients with adenocarcinoma of the pancreas: a population-based study (United States).

OBJECTIVE: The purpose of the current study was to evaluate survival of patients diagnosed in California with adenocarcinoma of the pancreas by demographic and tumor-related factors. METHODS: Through the California Cancer Registry (CCR) we identified all California residents diagnosed with invasive pancreatic adenocarcinoma between 1994 and 2000. Demographic, tumor and treatment information was extracted from the CCR, and socioeconomic status (SES) was assigned based on census block group of residence. RESULTS: A total of 10,612 eligible patients were identified of whom 1674 (15.8%) underwent surgical resection. Patients of lower SES were less likely to undergo resection and somewhat less likely to survive. Median survival was 3.5 months for patients who were not resected and 13.3 months for those who underwent resection. Adjuvant therapy was associated with a decreased risk of death among patients who underwent resection. CONCLUSIONS: This study is the largest population-based study to date to explore survival from pancreatic cancer among all age groups in a racially diverse population. Median survival was shorter than that reported from other series. Race/ethnicity did not have a significant effect on survival. However patients residing in poor neighborhoods were less likely to undergo resection and somewhat less likely to survive this disease.