Deaths from cancer accounted for more than 4 million potential years of life lost in 2017, according to a study published by Minkyo Song, MD, PhD, and colleagues in Cancer Epidemiology, Biomarkers & Prevention. While the cancer types with the highest death rates per capita accounted for the greatest number of years lost, cancers that typically occur at younger ages bore a disproportionate share of the burden.
“Potential years of life lost (PYLL) is an estimate of the average years a person would have lived if he or she had not died prematurely. Given that cancer is the leading cause of death in those younger than 80 years old, it is important to study the effect of cancer death rates among younger people,” said the study’s lead author Dr. Song, a research fellow at the National Cancer Institute, in a press release.
Minkyo Song, MD, PhD
In 2017, there were 599,099 cancer deaths in the United States, according to death certificate data from the National Center for Health Statistics. In this study, Dr. Song and colleagues used national mortality data from the U.S. National Center for Health Statistics, coupled with a commonly used definition of PYLL as the number of years lost prior to age 75, to quantify how many years of life were prematurely lost. They calculated that 4,280,128 years of life were prematurely lost due to cancer in 2017.
For the most part, PYLL mirrored overall U.S. cancer mortality trends. For example, lung cancer, the cancer type that causes the largest number of deaths, accounted for approximately 24.3% of U.S. cancer deaths and 20.8 % of PYLL. Colon/rectal cancer accounted for 8.8% of deaths and 9.6% of PYLL. Pancreatic cancer accounted for 7.3% of deaths and 6.6% of PYLL, while breast cancer accounted for 7.1% of deaths and 9.4% of PYLL.
One exception to this pattern was prostate cancer, which causes about 5.1% of U.S. cancer deaths but only 2% of PYLL. “Many of the deaths caused by this cancer occurred at older ages, resulting in fewer PYLL,” explained Dr. Song.
Another metric, PYLL per death, provided a useful tool to measure the burden from several rare cancers that typically affect younger people, said Dr. Song. For example, testicular cancer accounted for 0.1% of cancer deaths in 2017, and 0.3% of PYLL. Bone cancer accounted for 0.3% of deaths, but 0.7% of PYLL. Although these cancers did not contribute dramatically to overall cancer mortality, they caused the highest numbers of life years lost per death: testicular cancer had the highest PYLL per death, with an average of 34 years lost, followed by bone cancer, with an average of 26.4 years lost, and endocrine cancers (including thymus cancer), with an average of 25.2 years lost.
The total number of PYLL increased slightly from 1990, despite an overall decrease in cancer deaths. In 1990, there were 4,262,397 PYLL, compared with the 4,280,128 recorded in 2017. During this time, overall cancer mortality dropped from 214.9 per 100,000 in 1990 to 152.7 per 100,000 in 2017. The researchers found that the increase in PYLL was due to the growth of the U.S. population.
The study also showed that ethnic and racial minority groups account for a disproportionate share of the burden of premature cancer death. In 2017, 78% of all cancer deaths occurred in non-Hispanic White patients, but only 70% of PYLL occurred in this group. By contrast, Hispanic patients accounted for 7% of cancer deaths and 10% of PYLL, while Black patients accounted for 12% of cancer deaths and 15% of PYLL.
Overall, Dr. Song said, “PYLL is a useful ‘complementary measure’ to cancer mortality rates. Together, they provide a more detailed picture of the social and economic toll of cancer. PYLL can be used to estimate the impact of cancer death in younger populations. This metric highlights the enormous loss of life due to certain cancers that occur at younger ages, even if they occur infrequently.”
As a limitation, the researchers noted that the study relied on the cause of death reported on death certificates, which are subject to error. They also pointed out that other studies have used different definitions of PYLL, contributing to some differences across the body of research on this topic.
Disclosure: This study was funded by the Intramural Research Program at the National Cancer Institute. For full disclosures of the study authors, visit cebp.aacrjournals.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.