Correlation of unobserved incidence of cancer in earlier stages with the observed incidence

10634 Background: Population-level cancer registries report observed (screening or clinically detected) incident cancer cases. However, the underlying true cancer incidence may be higher than observed. We estimate the unobserved cancer incidence by stage for eight different cancers. Methods: Using the CDC’s National Program of Cancer Registries (NPCR) and the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) combined incidence databases, we first estimated observed incidence rates by cancer type and stage. Newly observed cancers in later stages must have existed at a previous point in time at an earlier stage (and age). Considering that, we used backward induction approach to estimate the unobserved incidence rate of cancer. We also accounted for mortality from competing factors before cancer was detected. Cancer progression between stages was defined by dwell times, which were synthesized in an ensemble approach from published literature and empirical estimates. We estimated unobserved annual incidence cases in early-stage (stages I and II) for the age 50+ population and compared them with observed incidence cases for each cancer type between 2015-2019. Results: The below table shows the annual unobserved and total (unobserved plus observed) cancer incidence by stage for the eight most prevalent cancers. We estimated that the top three cancers with the highest proportion of unobserved early-stage annual incident cases were lung (157,400 cancers unobserved out of 226,400 total), with 70% unobserved; pancreatic (34,700 annual unobserved out of 52,500 total), with 66% unobserved, and non-Hodgkin’s lymphoma (46,400 unobserved out of 73,600 total), with 78% unobserved. In contrast, the cancers with the lowest proportion of unobserved early-stage incident cases were breast (29,100/203,400 [14%]), urinary bladder (27,000/81,800 [33%]), and prostate (110,600/258,900 [43%]). Cancers with a high screening rate have lower unobserved early stage incidence than cancers with a low screening rate or without a screening test. Conclusions: We estimated a large undiagnosed incidence of cancer in early stages. This represents an opportunity for novel early detection technologies to detect cancer in earlier stages. [Table: see text]