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AACR Special Conference on Early Cancer Detection

The WHO outlines three essential components for effective and sustainable early detection: awareness and accessing care; clinical evaluation, diagnosis and staging; and treatment.

A key challenge is that barriers often limit opportunities for early detection. These include suboptimal cancer knowledge among the general population and at the primary health care level; poor accessibility; low affordability and quality of diagnostic follow-up; and delayed access to treatment.

Diagnosis

Early detection is about identifying cancers in the earliest stages of growth when they are less likely to spread and more treatable. It involves both symptom-based screenings, like pap smears, and targeted diagnostic testing for those at higher risk of certain cancers. Ultimately, it leads to improved treatment options, increased survival and better quality of life for patients.

Current cancer detection technologies such as imaging and molecular biomarker approaches are rapidly progressing to address the needs of a growing global market. However, despite advances in technology and biological understanding, more innovation is needed to increase the number of cancers detected at an early stage.

Developing a new generation of diagnostic tests capable of accurately distinguishing progressive from non-progressive disease and providing information about the biology and trajectory of precancer and early cancer remains a major challenge.

Insights about what drives progression should be translated into more sensitive and specific tests that could identify the small number of people with consequential cancer who need early intervention to delay the onset or limit their lethality.

Developing such novel diagnostic triage and testing strategies will require close collaboration between primary care, secondary care and research in cancer early detection. This will involve ensuring that new tests are cost-effective and improve patient safety, and quality of life while avoiding overdiagnosis.

It will also involve optimizing variables related to the test’s performance and provider interpretation (including interactions across components of the diagnostic work system distributed in space and time) to achieve early cancer detection with a high chance of success.

 

Screening

The goal of screening is to identify unrecognized disease in an apparently healthy, asymptomatic population by means of tests or examinations that are inexpensive and easily available. Screening is distinct from diagnostic intervention and is characterized by a high rate of false positive and negative results.

Effective screening requires a disease with sufficient severity to justify testing asymptomatic people; it must have an identifiable, accessible, detectable latent phase and a critical point where the prognosis worsens if not detected. The test must have a high sensitivity (how many actual cases does the screen identify) and a high specificity (how many healthy people do not get diagnosed at screening).

It is important to remember that diseases with a more rapid progression from latent phase to critical point may be over-represented among those identified by screening programmes, due to length-time bias. This is why a good benefit-harm balance must be achieved, including the risk of harm from screening methods themselves.

Biological insight is rapidly expanding, but to translate discovery into transformative progress in cancer detection, a broad range of skill sets — from pharmacologists to engineers and physicists to computer scientists — are needed. Interdisciplinary collaboration and innovation are key. The challenge is to design new tools and techniques that can accurately distinguish consequential, aggressive lesions from inconsequential ones.

Prevention

When cancer is prevented or caught early, survival drastically improves. However, 50% of cancers are at an advanced stage when diagnosed. Moreover, even when effective prevention and screening strategies are deployed, they do not reach all populations in need of them. This AACR Special Conference will leverage biological and mechanistic advances to inspire thinking about new approaches to preventive and predictive cancer interventions that aim to reduce incidence and mortality.

To achieve this, we need to elucidate the biology and trajectory of pre-cancer and early cancer to identify consequential diseases for intervention. We also need to develop and translate new preventive and screening technologies, ranging from biomarkers to imaging modalities, that are sensitive and specific enough for clinical implementation. Lastly, we need to integrate the individual component jigsaw pieces of risk-stratified prevention and screening programmes into a comprehensive healthcare system framework.

Many cancers can be prevented with lifestyle changes, such as limiting tobacco and excessive alcohol consumption, eating a healthy diet, and engaging in regular physical activity. Effective cancer screening is another powerful tool, and can dramatically increase the chance of detecting some types of cancer at an early stage when treatment options are most effective.

This includes routine breast self-exams, and scheduling monthly clinical breast exams and mammograms. Additionally, we encourage everyone to talk with their doctor about their individual risk for various cancers and discuss which screening tests are recommended.

Treatment

Treatment is more effective and survival dramatically improves when cancer is diagnosed in the earliest stages. But 50% of cancers are still diagnosed in the late stage when they are often no longer curable.

The main challenges in early detection are:

Developing better models of disease behaviour and progression will help us distinguish between consequential, aggressive lesions that warrant intervention, and inconsequential or ultra-low-risk lesions that do not. This will help minimize overtreatment.

The second challenge is improving the accessibility and affordability of screening and diagnosis services, especially in low- and middle-income countries. This is a challenge that requires multidisciplinary collaboration.

New approaches for cancer early detection are evolving rapidly. The emergence of genomics, the development of novel biomarkers, and advances in data analysis are accelerating progress.

A third challenge is ensuring that risk-stratified screening programmes can translate to improved patient outcomes in real-world settings. This requires the adoption of pragmatic randomized health service studies and hybrid effectiveness-implementation research designs. These will reduce the time lag between the generation of evidence on the effectiveness of a screening programme and its implementation.

It is also important to focus on the individual ‘jigsaw pieces’ of a prevention and screening programme and to build an understanding of how these work together. This will enable the integration of a screening strategy with other interventions that are designed to prevent or delay the onset of cancer, such as healthy lifestyle measures and prophylactic treatment for specific hereditary cancer predisposition syndromes.