Interstitial fluid pressure in breast cancer, benign breast conditions, and breast parenchyma

Interstitial fluid pressure (IFP) in rodent malignant tumors is reportedly much higher than in surrounding normal tissue. We hypothesized the same may be true in human invasive breast tumors. We measured IFP in the operating room in 25 patients undergoing excision breast biopsy under local anesthetic for diagnostic purposes. In patients with invasive ductal carcinomas IFP was 29 +/- 3 (SE) mm Hg, compared with -0.3 +/- 0.1 mm Hg in those with normal breast parenchyma (p < 0.001), 3.6 +/- 0.8 mm Hg in those with benign tumors (p < 0.003), -0.3 +/- 0.2 mm Hg in those with noninvasive carcinomas (p = 0.034), and 0.4 +/- 0.4 mm Hg in those with other benign breast conditions (p = 0.002). There was a direct correlation between IFP and tumor size (R2 = 0.3977; p = 0.021). No correlation was found between IFP and nuclear grade, angiolymphatic invasion, systemic blood pressure, metastasis to lymph nodes, or estrogen and progesterone receptors. IFP measurements may facilitate radiographic or ultrasound localization of small or nonpalpable malignant tumors in those patients undergoing needle aspiration cytology or stereotactic core needle biopsy.