A new study published in Cancer Epidemiology, Biomarkers & Prevention, a journal from the American Association for Cancer Research (AACR), found that a large portion of cancers of all types can be cured when diagnosed at early stages, but are less likely to be curable once the cancer has metastasized. 

Using a mixture cure model to analyze data from 2.4 million incident cancers followed for up to almost 15 years in the US Surveillance, Epidemiology, and End Results (SEER) cancer registries, researchers estimated cure fraction across stages for 21 cancer types and additional subtypes. Cure fraction is the proportion of people considered cured of cancer after long-term follow-up and reflects the total impact of cancer control strategies, including screening, without lead-time bias. Cured patients, from a statistical perspective, are those who achieve stable long-term survival with minimal risk of mortality from their initial cancer.

The study found that across cancer types, a substantial cure fraction was evident at early stages for each of the cancer types and subtypes examined. For many cancers, cure fraction was >50% higher in absolute percentage at stage I than stage IV. Such discrepancies in cure fraction were seen both in cancers with established screening methods (e.g., breast and colorectal cancers) and other types that lack current guideline-based screening strategies.

Results confirmed that stage at diagnosis is among the strongest predictors of long-term cancer outcomes, including survivorship trajectory and mortality risk, which differ starkly between localized and metastatic cancers. Notably, previous studies have not reported stage-stratified cure fraction across the spectrum of cancer types.

Understanding differences in cure fraction by cancer type and stage, in turn, sheds light on the potential for reducing the population burden of cancer through earlier detection, especially using new screening interventions including multi-cancer early detection (MCED) tests. MCED tests allow for efficient screening for many different types of cancer through a simple blood draw. They are designed to find more cancers at early stages, when long-term outcomes are far more likely to be favorable.

Additionally, the study found that differences by stage in 5-year cancer-specific survival were highly predictive of differences by stage in long-term cure fraction up to nearly 15 years after diagnosis across cancer types. Results confirmed that 5-year cancer-specific survival can serve as a predictor of long-term survival and may be a strong surrogate for more complex mortality models. This is important when considering the urgent need for accelerating clinical evaluation of MCED tests and their implementation into clinical practice.

We have long understood that early detection has the potential to reduce cancer death. New cancer detection technologies, including MCED tests, complement the existing standard of care and represent a compelling opportunity to bend the cancer mortality curve.