This study provides a comprehensive overview of cancer statistics in Korea for 2021, including incidence, mortality, survival, and prevalence. Key findings include: 1. **Incidence**: The number of new cancer diagnoses increased by 10.8% in 2021 compared to 2020, with a total of 277,523 new cases. Thyroid cancer saw the largest increase, followed by colorectal and lung cancers. Overall, the incidence rates increased by 3.3% annually until 2012, then decreased by 5.3% until 2015, followed by non-significant changes. 2. **Mortality**: Cancer was the leading cause of death in 2021, with 82,688 deaths. Lung cancer was the most common cause of cancer-related deaths, followed by liver and colorectal cancers. Mortality rates have been decreasing since 2002, with a more rapid decline in recent years. 3. **Survival**: The 5-year relative survival rate for cancer patients diagnosed between 2017 and 2021 was 72.1%, indicating significant improvements over the past two decades. 4. **Prevalence**: The total number of prevalent cancer cases in 2021 was 2,434,089, surpassing 2 million since 2018. Thyroid cancer had the highest prevalence, followed by stomach and colorectal cancers. 5. **Trends**: Since 1999, breast, pancreas, kidney, and hematologic cancers have shown continuous increases, while colorectal and bladder cancers have shown decreasing trends. Thyroid cancer experienced a significant increase from 1999 to 2011, followed by a decrease until 2016, and then another increase. 6. **Conclusion**: The study highlights the recovery of healthcare utilization and the impact of revised cancer registration guidelines on cancer statistics. The increasing number of cancer survivors and the need for comprehensive cancer control strategies are emphasized, along with the long-term impact of the COVID-19 pandemic on cancer statistics, which requires further investigation. The study underscores the importance of ongoing surveillance and research to address the evolving cancer landscape in Korea.This study provides a comprehensive overview of cancer statistics in Korea for 2021, including incidence, mortality, survival, and prevalence. Key findings include: 1. **Incidence**: The number of new cancer diagnoses increased by 10.8% in 2021 compared to 2020, with a total of 277,523 new cases. Thyroid cancer saw the largest increase, followed by colorectal and lung cancers. Overall, the incidence rates increased by 3.3% annually until 2012, then decreased by 5.3% until 2015, followed by non-significant changes. 2. **Mortality**: Cancer was the leading cause of death in 2021, with 82,688 deaths. Lung cancer was the most common cause of cancer-related deaths, followed by liver and colorectal cancers. Mortality rates have been decreasing since 2002, with a more rapid decline in recent years. 3. **Survival**: The 5-year relative survival rate for cancer patients diagnosed between 2017 and 2021 was 72.1%, indicating significant improvements over the past two decades. 4. **Prevalence**: The total number of prevalent cancer cases in 2021 was 2,434,089, surpassing 2 million since 2018. Thyroid cancer had the highest prevalence, followed by stomach and colorectal cancers. 5. **Trends**: Since 1999, breast, pancreas, kidney, and hematologic cancers have shown continuous increases, while colorectal and bladder cancers have shown decreasing trends. Thyroid cancer experienced a significant increase from 1999 to 2011, followed by a decrease until 2016, and then another increase. 6. **Conclusion**: The study highlights the recovery of healthcare utilization and the impact of revised cancer registration guidelines on cancer statistics. The increasing number of cancer survivors and the need for comprehensive cancer control strategies are emphasized, along with the long-term impact of the COVID-19 pandemic on cancer statistics, which requires further investigation. The study underscores the importance of ongoing surveillance and research to address the evolving cancer landscape in Korea.