과학/건강

Humanity has long battled the intractable problem of cancer. As recently as the mid-20th century, cancer was largely considered an 'incurable disease,' and a diagnosis often meant preparing for the time remaining. However, over the past half-century, cancer treatment has advanced at an astonishing pace. The three main pillars of surgery, radiation therapy, and chemotherapy were established, and with the advent of targeted therapies and immunotherapies in the 21st century, the paradigm of cancer treatment itself has shifted. We have now entered an era where we dream not just of 'slowing down cancer,' but of 'conquering cancer.'

Behind these changes are two core strategies. One is to detect cancer earlier and more accurately, and the other is to understand the nature of cancer at a molecular level and attack it in a personalized way. The recent focus on multi-cancer early detection (MCED) blood tests, AI-based research, and advances in precision medicine are trends that simultaneously strengthen these two pillars.

The First Step to Conquering Cancer: 'Earlier Detection'

What is the most powerful weapon in cancer treatment? Many experts unhesitatingly point to 'early detection.' Cancer often has few symptoms in its early stages. However, if detected when small and before it has spread to surrounding tissues or other organs, it can often be cured with surgery alone. Conversely, if detected after it has already metastasized, treatment becomes difficult and the prognosis worsens.

Until now, cancer screenings have been conducted separately for specific cancer types such as stomach cancer, colorectal cancer, breast cancer, cervical cancer, and liver cancer. This involved endoscopy, ultrasound, CT, MRI, or tumor marker blood tests. However, these tests required multiple hospital visits, and each test came with discomfort, cost, and sometimes the burden of radiation exposure or invasive procedures. Furthermore, cancer types not covered by screening were easily missed altogether.

To overcome these limitations, the concept of Multi-Cancer Early Detection (MCED) emerged. MCED tests are a technology that can screen for about 50 different types of cancer simultaneously with just one blood test. The core principle is to detect 'circulating tumor DNA (ctDNA)' floating in the blood. When cancer cells die or are destroyed, fragments of DNA are released into the bloodstream, and these fragments contain cancer-specific DNA methylation patterns or genetic mutations. MCED tests read these signals with high sensitivity to determine the 'possibility of cancer.'

In actual clinical studies, the performance of MCED tests is quite impressive. For a representative test like Galleri (GRAIL), the specificity is 99.5%, with a false positive rate of only 0.5%. This means that the accuracy is so high that only 5 out of 1,000 people without cancer are incorrectly identified as positive. The overall sensitivity is about 51.5%, meaning it can detect about half of cancer patients. In particular, sensitivity increases sharply as the stage progresses, detecting over 77% at stage 3 and over 90% at stage 4.

However, the sensitivity for stage 1 cancer is still limited at about 17%. This is because very early-stage cancers release a small amount of tumor DNA into the blood, making detection difficult. Therefore, MCED tests are more likely to be used as an auxiliary screening test or for repeated testing in high-risk groups, rather than completely replacing existing screenings. Nevertheless, the very fact that 50 types of cancer can be screened simultaneously with a single blood test has the potential to change the paradigm of cancer screening.

Currently, a large-scale randomized controlled trial (RCT) called NHS-Galleri is underway in the UK, involving approximately 140,000 people. The ultimate goal of this trial is to prove whether MCED tests actually reduce cancer mortality. As of 2026, interim results on test performance, diagnostic pathways after a positive result, and false positive management are being reported, with final results expected in the late 2020s to early 2030s. If a mortality reduction effect is proven in this trial, MCED tests are highly likely to be incorporated into global cancer screening guidelines.

The second pillar of conquering cancer: 'Understanding more accurately and attacking precisely'

To conquer cancer, early detection alone is not enough. Even for cancers originating in the same organ, genetic mutations and molecular characteristics differ from patient to patient, and even within the same patient, from one tumor site to another. Therefore, the approach of 'administering the same anticancer drug to all breast cancer patients' is no longer the optimal strategy. Instead, precision medicine, which precisely identifies the genetic mutations in each patient's tumor and which signaling pathways are excessively activated, and then selects targeted therapies or immunotherapies accordingly, is becoming the standard.

The core tool for such precision medicine is Next-Generation Sequencing (NGS). NGS allows for the simultaneous analysis of hundreds of genes from tumor tissue or blood, enabling the selection of drugs most likely to be effective for the patient. For example, if an EGFR mutation is found in a lung cancer patient, an EGFR targeted therapy is used, and if HER2 amplification is present in gastric or breast cancer, a HER2 targeted therapy is used.

Recently, even more sophisticated approaches have emerged. mRNA cancer vaccines are a prime example. While mRNA vaccines proved their efficacy during the COVID-19 pandemic, they are also being applied to cancer treatment. By creating a customized mRNA vaccine based on specific mutations (neoantigens) found only in cancer cells and injecting it into the patient's body, immune cells target these neoantigens and attack the tumor. Recent research has revealed that mRNA cancer vaccines suppress tumors by mobilizing new types of immune cells that were previously not well known. This is considered a result that opens new horizons in cancer immunotherapy.

In addition, liquid biopsy technology has emerged as a crucial pillar of precision medicine. Liquid biopsy is a technique that analyzes tumor-derived DNA circulating in the blood to monitor the genetic characteristics of tumors in real time. While traditional tissue biopsies are invasive and can only be performed once, liquid biopsies can be performed repeatedly, making them useful for early detection of resistance mutations that occur during treatment and for adjusting treatment directions. If MCED tests focus on determining 'whether or not cancer is present,' liquid biopsies are more specialized in tracking 'what genetic characteristics the cancer has and how it is changing.'

Artificial Intelligence Emerges as a New Driving Force in Cancer Research

Another innovative variable in the effort to conquer cancer is the emergence of artificial intelligence (AI). AI has now evolved beyond a data analysis tool, advancing to the point of discovering new drug candidates, predicting the molecular characteristics of tumors, and even predicting treatment responses. For example, AI models trained on hundreds of thousands of compound structures and biological activity data can screen new anticancer drug candidates much faster than before. Furthermore, by integrating and analyzing genomic, transcriptomic, and proteomic data of tumors, models can be built to predict which patients will respond to which drugs. This also significantly impacts clinical trial design, increasing the probability of success and shortening development time by pre-selecting the 'right patients.'

Especially recently, with the emergence of research automation systems in the form of AI agents, a research paradigm led by AI, from experimental design to data analysis and literature review, is becoming a reality. This has the potential to dramatically accelerate the pace of cancer research. However, since there is a risk that AI may learn incorrect data or draw biased conclusions, human oversight and verification systems must be accompanied.

AI is also contributing to improving the accuracy of cancer diagnosis in the field of radiology. AI algorithms assist doctors in interpreting imaging data such as CT, MRI, and PET scans by detecting subtle tumor signals. This is particularly useful for discovering small tumors in their early stages or recurrent tumors, and it can create synergy when combined with MCED tests. For example, if an MCED test yields a positive result, AI-assisted image analysis can more accurately pinpoint the tumor's location.

Cancer Conquest: How Far Have We Come?

So, have we actually gotten closer to conquering cancer? For some types of cancer, 'cure' has already become a reality. For example, early-stage breast cancer, colorectal cancer, and prostate cancer have very high cure rates with surgery and adjuvant therapy. Among pediatric cancers, acute lymphoblastic leukemia has a cure rate of over 90%. Additionally, chronic myeloid leukemia (CML) has become manageable as a 'chronic disease' due to the development of targeted therapies. However, there are still many intractable cancers. Pancreatic cancer, bile duct cancer, brain tumors (glioblastoma), and some lung cancers still have poor prognoses. To conquer these cancers, more research is needed, including the discovery of new therapeutic targets, modulation of the immune microenvironment, and overcoming tumor heterogeneity.

Nevertheless, compared to the past, the future of cancer treatment is much brighter. The foundation for conquering cancer is being laid in various aspects, including advancements in early detection technology, the popularization of precision medicine, accelerated AI-based research, and strengthened global cooperation systems. Experts predict that the 5-year survival rate for major cancer types will rise to over 70% by the mid-2030s. Of course, there are still many challenges to address. Society as a whole must pool its wisdom to tackle various issues such as cost, accessibility, ethics, and overdiagnosis. However, what is clear is that conquering cancer is no longer an impossible dream. If the advancements in science and medicine, combined with the efforts of individuals and society, come together, in the not-too-distant future, cancer will be recorded as a 'conquerable disease' rather than just a 'manageable disease.'

The journey to conquer cancer has already begun. And at the end of that journey, a world where more people can live healthy and long lives awaits.