shows the distribution of the cause of death as reported on the death certificates by cancer site. Of the 229,181 patients included in our analysis, 192,538 (84%) reportedly died from the same site-specific cancer as their incident diagnosis in SEER. An additional 8% were reported to have died of another cancer. Less than 9% of the sample had a cause of death listed as other than cancer. Among patients with only one primary cancer recorded, there was substantial agreement between incident cancer site diagnosis and reported cause of death. For patients with a single primary diagnosis, the percentage of deaths attributable to site-specific cancers exceeded 80% for lung (87%), pancreatic (87%), breast (85%), and ovarian (85%) cancers. The poorest agreement was for patients with head and neck (58%), liver (71%), and uterine (72%) cancers. For patients with only one cancer diagnosis, the cause of death was recorded as cancer (either site-specific or cancer cause-specific, excluding site-specific) in at least 85% of all cases, for 9 of the 11 cancer sites, included in our analysis. The exceptions were for prostate (78%) and head and neck (84%) cancer.
Cause of Death Reported by Number of Primary Cancers for Patients Diagnosed With Distant Stage Cancer From 1994 to 2003 and Who Were Deceased as of December 31, 2005
When the “cancer cause-specific, excluding site-specific” category represented more than 10% of all deaths and the patient was diagnosed with only one primary cancer, we identified the most commonly coded cancer sites on the death certificate. Among patients with a primary diagnosis of melanoma of the skin, liver, or head and neck cancer, the most frequently coded other cancer cause of death was miscellaneous malignant cancers (C26.1, C45.7, C45.9, C76-C80, C88, C96.0-C96.2, C96.7, C96.9, C97), with 46%, 57%, and 61%, respectively. Among patients diagnosed with melanoma of the skin, another 17% were coded as lung and bronchus. An additional 15% of liver cancer patients were coded as intrahepatic bile duct deaths. Head and neck cancer patients with another cancer cause of death were attributed to skin, excluding basal or squamous cell, 13%, or lung or bronchus, 11%. Among gastric cancer patients, 59% were reported to be an esophageal cancer cause of death with another 18% classified as miscellaneous malignant cancers. Nearly 53% of uterine cancer patients were reported with another female gynecologic cancer cause of death on the death certificate.
The percentage of patients with agreement between the initial diagnosis and site-specific cause of death was lower for patients with multiple primaries. For these patients, the site-specific cause of death agreed in 66–75% of patients with pancreatic, lung, breast, colorectal cancers, and melanoma of the skin. Patients with prostate and head and neck cancers who had multiple primaries had the lowest reported site-specific cancer deaths, 39% and 36%, respectively. However, the percentage of patients with multiple cancers who reportedly died of cancer of any site was high at 90%.
Because of the challenges in attributing cancer deaths for patients with multiple cancers, we restricted additional analyses to patients with only one primary cancer diagnosis. We considered, by cancer site, whether the percentages of deaths attributable to site-specific cancers, cancer cause-specific, or other causes differed by age, race/ethnicity, and sex. As shown in , for all cancers, the percentage of patients dying from causes other than cancer increased with age, and the trend was statistically significant for all cancer sites (p <.05), except liver. For the vast majority of cancers, black and Hispanic patients were more likely than white patients to have a reported cause of death other than cancer. The percentage of deaths recorded on the death certificate as site-specific or any cancer cause of death did not vary by sex, except for gastric cancer where women had a higher percentage of site-specific cancer cause of death (data not shown).
Selected Demographic Characteristics for Patients Diagnosed With Only One Primary Distant Stage Cancer From 1994 to 2003 and Who Had Died as of December 31, 2005
We examined whether the cause of death on the death certificate varied with the length of time from diagnosis to death (). For most cancers, percentages of reported site-specific and cancer cause-specific deaths remained comparable across time. For colorectal, lung, and prostate cancers, the percentages of patients with site-specific cancer causes of death varied by time from diagnosis to death (p <.001), generally increasing through year one and decreasing through years two and three. In ovarian cancer patients, the site-specific percentage mono-tonically increased as time from diagnosis to death increased (p <.001).
Cause of Death Reported for Patients Diagnosed With Only One Primary Distant Stage Cancer From 1994 to 2003 and Who Were Deceased as of December 31, 2005, by Time From Diagnosis to Death