Innovative Blood Test Could Detect Cancers Early, Reducing Late-Stage Cases

A recent study published in BMJ Open reveals that a novel blood test, known as a multi-cancer early detection test (MCED), has the potential to significantly reduce the progression of various cancers to late stages, possibly affecting up to half of cases diagnosed. This test can identify chemical markers associated with multiple cancer types, offering a proactive approach to cancer management.

Currently, reliable screening methods are available for a limited number of cancers, including breast, bowel, cervical, and lung cancers in high-risk individuals. Although these screenings have contributed to lower mortality rates, they are not without drawbacks, such as false positives and the risk of overdiagnosis. The study emphasizes the need for a clearer understanding of the optimal frequency for screenings that would maximize early detection rates while minimizing unnecessary interventions.

To evaluate the potential benefits of the MCED test, researchers utilized a previously established model of cancer progression. They aimed to predict how regular screenings with the MCED test would affect the timing of cancer diagnoses and patient survival rates among individuals aged 50 to 79 receiving standard care. Various screening intervals, ranging from six months to three years, were analyzed, with a focus on annual and biennial testing schedules.

The cancers examined in this study encompassed a wide range, including those of the anus, bladder, breast, cervix, bowel, esophagus, gallbladder, head and neck, kidney, liver, lung, ovary, pancreas, prostate, stomach, thyroid, uterus, as well as blood cancers such as leukemia and lymphoma.

The findings indicated that all modeled intervals of MCED screenings resulted in higher rates of early-stage cancer diagnosis compared to standard care alone. Specifically, annual screenings showed the most significant impact on early detection, particularly for tumors characterized by rapid growth. Under the fast tumor growth scenario, annual MCED screenings could detect an additional 370 cancer signals annually per 100,000 individuals screened, resulting in a 49% reduction in late-stage diagnoses and a 21% decrease in five-year mortality rates compared to standard care.

In contrast, biennial screenings also demonstrated benefits, though they were less pronounced. This approach detected 292 additional cancer signals per year per 100,000 people screened, leading to a 39% reduction in late-stage cases and a 17% decrease in five-year mortality. While biennial screenings had a higher positive predictive value--54% compared to 43%--indicating more accurate results per test, they ultimately prevented fewer deaths than annual screenings.

The researchers projected that both annual and biennial MCED screenings could intercept 31% to 49% of cancers at stages I and II that would otherwise progress to stages III and IV. They noted that an equal distribution of early-stage detections could be expected between stages I and II, with some estimates suggesting around 14% at stage I and 16% at stage II for annual screenings.

It is important to highlight that these findings assume complete adherence to the proposed screening schedules and flawless accuracy in subsequent confirmatory tests, suggesting that the benefits outlined may represent an upper limit. Reducing late-stage cancer diagnoses is believed to correlate with lower mortality rates; however, the actual effectiveness of these screenings will depend on real-world implementation, including compliance and the costs associated with follow-up testing.

Overall, the research supports the integration of MCED testing into existing cancer screening protocols, indicating that both annual and biennial screenings could contribute to lower mortality rates from advanced cancers.