Why in the News?

A multi-cancer early detection test can identify circulating tumour DNA or circulating tumour cells at an early stage, allowing for more effective treatment.

Status of Cancer:

• Cancer’s Impact in India: Cancer accounts for 18% of deaths from noncommunicable diseases in India, making it the second leading cause of mortality. In 2022, there were approximately 1.46 million new cancer cases, with projections indicating a 12% increase by 2025.
• Common Cancers as per GLOBOCAN: Among women, the most prevalent cancers are breast, cervical, ovarian, and colorectal.
  • For men, lung, esophageal, colorectal, and stomach cancers are the most common.
• Survival Rates and Detection: Late detection of cancer significantly reduces survival rates and increases treatment costs. In contrast, early detection through screening improves treatment outcomes and quality of life. 
  • Countries are aligning with the United Nations’ Sustainable Development Goals 3 to enhance early cancer detection.
• Limited screening: As per NHFS, screening is limited in India which is primarily to cervical, breast, and oral cancers, with only 0.2-2% of the population having undergone any form of screening.

What is a Multi-Cancer Early Detection (MCED) Test?

• A multi-cancer early detection (MCED) test is a new type of blood test that can screen for multiple types of cancer simultaneously. These tests look for cancer signals, such as circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs), released by cancerous cells into the bloodstream at early stages.

Role of Blood-based tests in the detection of cancer:

• Early Detection of Multiple Cancer Types: Blood tests, particularly multi-cancer early detection (MCED) tests, can identify cancer signals from over 50 different types of cancer, including those that currently lack effective screening methods.
  • For example, a recent study demonstrated that a new blood test could detect 93% of stage 1 cancers in men and 84% in women by analyzing protein biomarkers.
• Non-Invasive and Accessible Screening: Blood tests are non-invasive and can be performed with a simple blood draw, making them more accessible compared to traditional screening methods like colonoscopies or imaging tests. This ease of use encourages more individuals to participate in screening.

Limitation of blood test in the detection of Cancer:

• Lack of Proven Mortality Benefit: It is still unclear whether detecting cancers earlier with MCED tests will actually reduce cancer deaths. More research is needed to determine if earlier treatment based on MCED results improves outcomes compared to waiting for symptoms to develop.
• Regulatory Challenges: MCED tests are not yet approved by regulatory bodies like the U.S. FDA or India’s CDSCO because of not undergone rigorous premarket review to prove they benefit patients.
• False Positives: One significant risk is false positive results, where the test indicates cancer when none is present. When multiple tests are used for screening, the false positive rate can be as high as 50%.

Way forward:

• Strengthening Screening Infrastructure and Research: India should invest in expanding its cancer screening infrastructure, ensuring that more types of cancer are included beyond cervical, breast, and oral cancers.
• Public Awareness and Regulatory Preparedness: Increasing public awareness about the importance of early cancer detection is crucial. At the same time, regulatory bodies like CDSCO should establish clear guidelines and frameworks for the evaluation, approval, and monitoring of MCED tests.

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