When cancer is detected early, treatment is more effective, and survival rates improve. So why are almost half of the cancers still diagnosed at advanced stages, although blood tests and other screening methods have been around for decades? The challenges related to early detection are complex, just as the disease itself.

Early detection can be done at different stages of the disease development from normal cellular activity to dysregulation to cancer. Finding the often subtle changes early would ideally be done by screening, which proactively tests asymptomatic people, who usually are individuals at higher risk due to age or family history.

Established screening methods like mammography for breast cancer and colonoscopy for colorectal cancer have demonstrated success in lowering death rates through early intervention. However, not all diseases can be screened, including ovarian cancer, which often remain hidden until they reach advanced, untreatable stages, leaving physicians and patients with limited options.

Ovarian cancer is notorious for its vague symptoms and lack of effective screening methods, making early detection a significant challenge. This disparity between the success in detecting some cancers early and the difficulty with others highlights an urgent need: we must develop innovative approaches to detect these silent killers sooner.

Balancing benefits and risks

One screening solution with high expectations has been blood tests, such as the CA-125 test for ovarian cancer, in an attempt to detect cancers earlier— with the expectations for the identification of cancer patients among the general population of high-risk individuals.

Initial excitement on early promising findings has since ceded as it is now known that CA-125 is also elevated in non-cancerous benign conditions to the extent that the primary diagnosis of ovarian cancer in non-symptomatic individuals is untenable. Many well-planned screening programs using CA-125 blood tests have revealed challenges that cannot be overlooked. One of the primary concerns is overdiagnosis, which leads to unnecessary treatments, exposing patients to side effects and emotional stress without tangible benefit. Furthermore, the psychological impact of a cancer diagnosis, even if the cancer is indolent, can be profound.

Peering into the future

So, how do we navigate these challenges to harness the benefits of early detection while minimizing the harms? The future likely lies in more nuanced, individualized approaches to screening and diagnosis through multimodality. Moving away from a one-size-fits-all model, healthcare providers could integrate information from blood tests, genetic factors, family history, lifestyle, and environmental exposures to classify individuals into different risk categories.

High-risk individuals might receive more frequent and advanced screenings, while those at lower risk could avoid unnecessary procedures. This stratified approach aims to maximize the benefits of early detection for those who need it most while reducing potential harm to others.

The downside of going multimodal lies in resources: with the expected rise of cancer incidence in the coming decades, healthcare systems will likely struggle to accommodate widespread, advanced screening programs. Not to mention that only high-income countries actually have the resources to implement such programs.

Blood tests: simple, affordable and accessible

The solution must be inclusive. For these advances to make a global impact, they need to be affordable and accessible, particularly in low- and middle-income countries where late-stage diagnoses are more common. Bridging this gap is essential to ensure equity also in cancer care.

This is where blood tests, simple immunoassays that can be used in decentralised settings, could be useful: as first-line screening tools before the diagnosis. Immunoassays are cost-effective tests that detect specific proteins or associated markers. They are relatively easy to operate and can be scaled for widespread use, making them ideal for initial screening, especially in resource-limited settings.

Whatever the solution will be, it’s clear that more research and innovations, including cross-sector collaborations, are needed to effectively integrate early detection into existing healthcare systems, resulting in evidence-based early interventions without compromising patient well-being or overburdening healthcare systems.

Janne Leivo

InFLAMES group leader