Phesi, the clinical data company known for tracking global medical research trends, has released its annual ranking of the world’s most-studied diseases, cementing breast cancer’s position at the top for the fifth year in a row. The 2025 list, announced December 30, shows few changes from 2024.
Following breast cancer, the top five most-studied diseases are solid tumors, stroke, prostate cancer, and non-small cell lung cancer. Obesity narrowly missed the top five, ranking sixth. Phesi compiled the list by analyzing 65,892 actively recruiting clinical trials worldwide.
“Breast cancer remains a dire disease with many subtypes, making it a natural focal point for research,” said Gen Li, Ph.D., Phesi’s president and founder. The report also highlighted triple-negative breast cancer (TNBC), a particularly challenging subtype that lacks HER2, estrogen, and progesterone receptors, and exhibits a high rate of phase 2 trial terminations.
Li emphasized that the “negative” label in TNBC is somewhat misleading. Instead, research should focus on identifying the specific receptors and proteins that are present in these tumors to guide more effective therapies.
The report also notes a shift in the landscape of clinical trials since the Covid-19 pandemic. The rate of phase 2 trial terminations spiked to 30% in 2022 but fell to 26% in 2025, still above pre-pandemic levels. Many trials end prematurely due to lackluster phase 1 results or challenges in recruiting sufficient patient populations.
Li advocates for more strategic use of the vast amounts of available clinical data to better design trials and reduce avoidable failures. “Optimizing trials ahead of time can help prevent attrition and ensure resources are focused on the most promising therapies,” he said.
Phesi’s report serves as a snapshot of global research priorities and highlights the ongoing challenges in developing treatments for some of the world’s most complex diseases.
