Breast Tissue Stiffness in Compression is Correlated to Histological Diagnosis

Many researchers have proposed imaging the stiffness distribution in breast tissue to enhance diagnosis of disease. They suppose that cancers are much stiffer than the surrounding tissue but to our knowledge no measurements have been made of these properties that accurately characterize them over a wide range of strain. We hypothesize that there is a correlation between elastic modulus in compression and histological diagnosis (e.g. infiltrating ductal carcinoma, normal glandular tissue, etc.). We also hypothesize that the cancer exhibits greater non-linearity; its change in modulus with strain is greater. We present a correlation that allows elastic moduli to be estimated from force displacement curves measured during punch indentation testing. The tissue samples tested were obtained during surgery and were tested immediately after removal from the body. We found that there is a significant difference in the stiffness and the rate of increase in stiffness with strain between cancerous and benign breast tissues. Infiltrating ductal cancer is more than 10 times as stiff as normal fat tissue at 1% strain, and more than 70 times as stiff at 15% strain. Compared to normal glandular tissue, this type of cancer is more than 2.5 times as stiff at 1% strain and nearly 5 times as stiff at 15% strain. Therefore, relative stiffness is a good indicator of histological diagnosis.