City of Hope Study Reveals Obesity Increases Cancer Risk by Physically Enlarging Organs and Multiplying At-Risk Cells

City of Hope researchers find that obesity enlarges organs by adding more cells, creating more opportunities for DNA errors and doubling cancer risk.

By: AXL Media

Published: Mar 27, 2026, 11:07 AM EDT

Source: Information for this report was sourced from City of Hope.

Beyond Hormones: The Physical Toll of Excess Weight

While the link between obesity and cancer has long been attributed to chronic inflammation and hormonal imbalances, a new study published in Cancer Research suggests a more direct, structural mechanism. Scientists at City of Hope have discovered that as the body gains weight, internal organs expand to meet the increased metabolic demands of a larger frame. This enlargement is not just "fatty" tissue growth; it is a literal increase in the number of functional cells, each of which represents a new "lottery ticket" for a potentially malignant mutation.

Quantifying Organ Growth Across the BMI Spectrum

In the first study of its kind, researchers used CT scans to measure the liver, kidneys, and pancreas of 747 adults ranging from underweight to severely obese. The data revealed a consistent, linear relationship between body mass and organ dimensions. For every 5-point increase in Body Mass Index (BMI), the researchers observed significant growth:

Liver: 12% increase in size

Kidneys: 9% increase in size