We know that cancer deaths are going down dramatically, in part because of better screening and new drugs, but can we get a closer look on how that is happening? A large, multi-institutional team led by researchers at the National Cancer Institute (NCI) looked at that question for several leading cancers: Colorectal, lung, breast, cervical, and prostate cancer from 1975–2020. They found an estimated 5.94 million deaths were averted from these five cancers combined.
The study was published last week in JAMA Oncology. The lead author was Katrina Goddard, director of NCI’s Division of Cancer Control and Population Sciences. It was released on the heels of another study which showed a 62% reduction in cervical cancer in young women, after the introduction of HPV vaccination, which was relatively late to impact the NCI study. But clearly certain interventions can have bigger effects.
This team used a model-based study to ask: What was the contribution of prevention, screening, and treatment interventions to avert deaths in breast, cervical, colorectal, lung, and prostate cancer from 1975–2020? They found that prevention and screening accounted for eight of every ten averted deaths and the contribution varied by cancer site.
This study aimed to quantify the contributions of prevention, screening (to remove precursors [interception] or early detection), and treatment to cumulative number of cancer deaths in those cancers during that time frame.
The study used population-level cancer mortality data. Outputs from published models developed by the Cancer Intervention and Surveillance Modeling Network were extended to quantify cancer deaths averted through 2020. Model inputs were based on national data on risk factors, cancer incidence, cancer survival, and mortality due to other causes, and dissemination and effects of prevention, screening (for interception and early detection), and treatment. Simulated or modeled data using parameters derived from multiple birth cohorts of the U.S. population were used.
Interventions tracked were: smoking reduction (lung), screening for interception (cervix and colorectal) or early detection (breast, cervix, colorectal, and prostate), and therapy (breast, colorectal, lung, and prostate). The team focused on these five cancer sites because they are among the most common causes of cancer deaths, and interventions are available for their prevention, interception and/or early detection, and treatment advances.
An estimated 5.94 million cancer deaths were averted for breast, cervical, colorectal, lung, and prostate cancers combined. Cancer prevention and screening efforts averted eight of ten of these deaths (4.75 million averted deaths).
The contribution of each intervention varied by cancer site:
Screening accounted for 25% of breast cancer deaths averted. Averted cervical cancer deaths were nearly completely averted through screening and removal of cancer precursors as treatment advances were modest during the study period. Averted colorectal cancer deaths were averted because of screening and removal of precancerous polyps or early detection in 79% and treatment advances in 21%. Most lung cancer deaths were avoided by smoking reduction (98%) because screening uptake was low and treatment largely palliative before 2014. Screening contributed to 56% of averted prostate cancer deaths.
The authors write: “Over the past 45 years, cancer prevention and screening accounted for most cancer deaths averted for these causes; however, their contribution varied by cancer site according to these models using population-level cancer mortality data. Despite progress, efforts to reduce the US cancer burden will require increased dissemination of effective interventions and new technologies and discoveries.”
The authors add: “The reignited Cancer Moonshot goal to reduce the age-adjusted cancer mortality rate by 50% in the next 25 years will not be achieved without accelerating progress. A comprehensive plan to reduce cancer mortality includes interventions in cancer prevention, detection, diagnosis, treatment, and survivorship care.”
