Tissue Dielectric Constant Differentials between Malignant and Benign Breast Tumors.

Introduction: This study's purpose was to characterize tissue dielectric constant (TDC) values of malignant and benign breast tumors and assess the potential utility of TDC differentials to help distinguish between malignant and benign tumors.

Methods: Prior to their diagnostic biopsy, TDC was measured at 300 MHz in 59 women with previously detected breast tumors. TDC measurements were made by touching skin directly over the tumor and on the non-affected breast with a hand-held 22 mm diameter probe. Each measurement took less than 10 seconds. An inter-breast TDC ratio (RATIO) was calculated as the ratio of the tumor breast TDC value divided by the non-affected breast TDC value measured on the contralateral breast at a corresponding anatomical site. Absolute TDC values and RATIOS were compared for malignant and benign tumors based on post-measurement biopsy determinations.

Results: Biopsy findings indicated tumors were malignant in 29 patients and benign in 30. Compared to the non-affected breast, malignant tumor TDC values were greater (P = .0002) whereas for benign tumors, there was no inter-breast difference (P = .256). No patient with a benign tumor exceeded a RATIO of 1.15 whereas 12 of the 29 patients with malignant tumors exceeded this threshold and tended to have larger volume tumors.

Conclusion: A tentative threshold RATIO of 1.15 may be discriminatory between malignant and benign tumors if the tumor is sufficiently large. Further research using a probe with a greater penetration depth is warranted to potentially increase discrimination.