Causes of death among cancer patients as a function of calendar year, age, and time after diagnosis

Abstract

Background: Our objectives are to characterize the causes of death among cancer patients as a function of: (I) calendar year, (II) patient age, and (III) time after diagnosis. The results would: (1) characterize patient risk to die of cancer- and non-cancer-death; (2) identify those who might profit from intense screening for second cancers; and (3) identify cancers that would most benefit from further research. Method(s): We used death certificate Da ta in SEER Stat 8.2.1 to categorize cancer patient death as being due to index-cancer, non-index-cancer, and non-cancer cause, in the USA from 1973 to 2012. In addition, Da ta were characterized with standardized mortality ratios (SMRs), which provide the relative risk of death as compared to all persons in the USA. A total of 28 cancers and 13 non-cancer causes of death were analyzed. A minimum of 1,000 person-years-at-risk were necessary for analysis of each disease site. Result(s): With respect to objective I, there were 1,895,788 deaths: 1,065,324 due to index-cancer, 204,453 due to non-index-cancer, and 626,011 not due to cancer. Over the entire time period, the greatest relative decrease in index-cancer death (generally from > 60% to < 30%) was among those with cancers of the testis, kidney, bladder, endometrium, breast, cervix, prostate, ovary, anus, colorectum, melanoma, and lymphoma. Index-cancer deaths (typically > 40%) were stable among patients with cancers of the liver, pancreas, esophagus, and lung, and brain. Non-cancer causes of death were highest in patients with cancers of the colorectum, bladder, kidney, endometrium, breast, prostate, testis; >40% of deaths were from heart disease. For objectives II/III, the cancers with high SMRs tended to be of immunologic/hematologic origin; and lung cancer. The highest SMRs were from non-bacterial infections, particularly among < 50 year olds (e.g. SMR > 1,000, p <0.001) with leukemias/ lymphomas; SMRs were inversely associated with patient age at time of diagnosis. The highest SMRs were within the first year after diagnosis (SMRs 2-200, p < 0.001). During follow-up of > 2-10 years, prostate cancer patients had increasing SMRs from Alzheimer's disease, as did testicular patients from suicide. Conclusion(s): The risk of death from index- and non-index-cancers varies widely among primary sites. Risk of non-cancer deaths now surpasses that of cancer deaths, particularly for young patients in the year after diagnosis.