Global Burden of Rare Cancers: Insights from GLOBOCAN 2022 Estimates

Background: Rare cancers, defined as those with an incidence rate of fewer than 6 cases per 100,000 individuals, contribute to a substantial portion of the global cancer burden. Despite their impact, they receive less attention than more common malignancies, leading to challenges in early detection, treatment strategies, and research funding. This study aims to assess the global incidence and mortality patterns of rare cancers in 2022 to better understand their contribution to the overall cancer burden and regional disparities. Methods: We conducted a comprehensive analysis using 2022 GLOBOCAN estimates to assess the global incidence and mortality of rare cancers. The study included 24 major rare cancers, such as bladder cancer, leukemia, non-Hodgkin lymphoma, esophageal cancer, and pancreatic cancer. Age-standardized rates (ASRs) were calculated to compare cancer burden across continents, and absolute case and death counts were reported. Results: In 2022, rare cancers accounted for 26.7% of all new cancer cases (5,347,784 cases) and 30% of all cancer-related deaths (2,959,369 deaths) worldwide. Bladder cancer was the most common rare cancer, with an incidence rate of 5.58 per 100,000, followed by non-Hodgkin lymphoma (5.57) and leukemia (5.26). Mortality rates were highest for pancreatic, esophageal, and brain cancers, reflecting their aggressive nature and limited treatment options. Significant regional disparities were observed, with Europe and North America reporting the highest incidence rates for bladder cancer and leukemia, while Asia bore the largest absolute burden of rare cancers. Conclusions: Rare cancers represent a considerable share of the global cancer burden, with notable geographic variations in incidence and mortality. These findings underscore the need for improved early detection, expanded treatment access, and targeted research efforts to address disparities and improve outcomes for patients with rare cancers worldwide.