Intratumoral acetic acid injection eradicates human prostate cancer tumors in a murine model

Abstract

To treat localized prostate cancer without substantial morbidity, an ideal treatment would be an effective local therapy with minimal morbidity. Direct injections have been used to treat benign prostatic hyperplasia without major complications, but in limited cases. We evaluated the local oncotoxic effects of acetic acid in a prostate cancer xenograft murine model. PC3 and LNCaP human prostate cancer cell lines were used to grow subcutaneous tumors in SCID mice. For each cell line, 14 mice underwent intratumor injection with 25% acetic acid (0.05 ml/100 cm3 of tumor) after the tumor was >300 mm3. Post-treatment one mouse/group was euthanized after 2 h, 24 h, 1 and 2 weeks; remaining mice (n = 10) were killed at 120 days. Control mice (8/group) were euthanized after they met the humane criteria for tumor burden and overall health. Tumor necrosis was noted immediately post-injection; by 24 h, ulceration and crusting of overlying skin were noted, which healed into scars by 23 ± 5 days. Histological examination showed tumor degeneration and necrosis with blood vessel obstruction. Ten treated mice in both groups survived for 120 days, which was much longer than the mean survival of PC3 (40 ± 9 days) and LNCaP (56 ± 10) control mice. Direct injection of acetic acid successfully eradicated both tumors. This treatment option could potentially be used in humans for treatment of early localized prostate cancer and nonoperative management of locally advanced cases. This is the first report of successful local chemical therapy for prostate cancer.