Screened, but not finished

Cancer screening is often discussed as a simple question of access or uptake: did someone get screened or not? But a new multi-site study published in the Journal of the National Cancer Institute (JNCI) argues that this framing is far too limited. Screening, on its own, does not prevent cancer mortality. Prevention happens only when abnormal results are tracked, followed up, and acted on in time. The researchers in this study shift attention away from screening as a single event and toward what they call the “screening continuum,” which includes initial screening, surveillance for abnormal but non-diagnostic findings, diagnostic evaluation for concerning results, and treatment initiation when cancer is found. Their central concern is not whether screening works in theory, but whether health systems are actually delivering the full chain of care needed for screening to work in practice.

Led by investigators from the Population-based Research to Optimize the Screening Process II (PROSPR II) consortium, including senior author Dr. Christopher Li at Fred Hutch Cancer Center, the study looks beyond screening uptake to examine the full “screening continuum” for cervical, colorectal, and lung cancers. “The full efficacy of cancer screening programs can only be realized if each step in the screening continuum is completed in a timely manner,” Dr. Li explains. “In this article, we describe important gaps in the delivery of screening, surveillance, and diagnostic evaluations consistent with current guidelines.”

Instead of assuming that everyone of a certain age was “due” for screening, the research team took a more nuanced approach. They looked back at records from 2018 and identified people who were actually eligible for each step of the cancer screening process based on prior test results and clinical guidelines. That distinction matters, because it let them ask a much more practical question: when care is clearly indicated, does it happen—and does it happen on time? They then calculated the proportion of patients who received timely screening, surveillance, diagnostic follow-up, and treatment, and examined how these outcomes varied by age, race and ethnicity, insurance status, and neighborhood socioeconomic status.

Their findings challenge how success in cancer prevention is often measured. For cervical cancer, only 41.8% of eligible women received timely screening, and around 37% completed recommended surveillance. Diagnostic follow-up performed somewhat better (61%), but still left many patients behind. Colorectal cancer showed a different but equally concerning pattern. Screening rates were relatively high, exceeding 80% among those known to be due, but surveillance dropped to under 50%. Among those with abnormal screening results, 73.5% completed timely diagnostic evaluation, and once colorectal cancer was diagnosed, 94.1% initiated treatment within three months. In other words, the system did a decent job getting people screened, but struggled to follow through when ongoing monitoring was needed. Lung cancer stood out with higher completion rates for surveillance (80.5%) and diagnostic evaluation (80.7%), suggesting that some screening programs may be better equipped to manage follow-up than others. Still, screening itself was not universal, and disparities remained. Across all three cancers, surveillance emerged as a consistent weak point, which is an in-between step that is easy to overlook, but essential for preventing cancer progression.

Equally important were the inequities that surfaced across the continuum. Insurance status and socioeconomic conditions were strongly associated with access at nearly every step. “We identified key gaps in care across these processes for all three cancers and significant disparities particularly related to insurance type and socioeconomic status,” Dr. Li noted. “For example, uninsured women had substantially lower rates of cervical cancer screening, surveillance, and diagnostic testing compared to women with private health insurance.” These gaps were not confined to screening alone; they compounded as patients moved, or failed to move through subsequent stages of care.

The study also highlighted how patients with no documented screening history in a health system were far less likely to receive timely screening at all. This finding underscores a structural reality that cancer prevention systems often work best for people who are already engaged, documented, and continuously connected to care. Those on the margins are more likely to be missed entirely.

Looking ahead, these findings raise pressing questions about how cancer prevention is organized and evaluated. “These results point to ongoing needs for new interventions and policies to improve the efficacy of the cancer screening continuum, particularly for populations experiencing the greatest disparities in receipt of recommended care,” Dr. Li said. “Our team will continue to focus on efforts that can improve the screening process.”

This study was supported by the National Cancer Institute through the PROSPR II consortium.

Fred Hutch/University of Washington/Seattle Children’s Cancer Consortium Member Dr. Christopher Li contributed to this research.

Haas, J. S., Todd, K. W., Mclerran, D., Tiro, J. A., Vachani, A., Kobrin, S., Saia, C., Sugg Skinner, C., Zheng, Y., Chubak, J., Corley, D. A., Greenlee, R. T., Halm, E. A., & Li, C. I. (2025). Gaps in care across the cancer screening continuum for cervical, colorectal, and lung cancers. Journal of the National Cancer Institute, 117(12), 2556–2570.