OBJECTIVETo study the effects of implantation brachytherapy with delayed-release particles of 32P-chromic phosphate-poly (L-lactide) (32P-CP-PLLA) on prostate cancer (PCa) in nude mice.

METHODSWe established a subcutaneous transplantable PCa model in nude mice, and randomly divided them into six groups, Groups A, B and C implanted intratumorally with 32P-CP-PLLA delayed-release particles at 3.7, 7.4 and 14.8 MBq, Groups D, E and F with 125I particles at the same doses as the former three, and another six nude mice were included in Group G as the blank control. Then we killed the mice at 21 days after the treatment, observed the effects of the particles on the morphology of the tumor and their inhibition of tumor growth, counted WBCs and platelets (PLTs) in the peripheral blood, and detected the toxic reaction of the blood.

RESULTSAt 21 days after the treatment, the solid tumor tissues exhibited bleeding and necrotic changes, and the rates of tumor inhibition were positively correlated with the doses of administration. Groups A, B and C showed statistically significant differences from Groups D, E, F and G in the rate of tumor inhibition ([ 65.72 +/- 6.95]%, [77.58 +/- 4.32]% and [82.64 +/- 4.03]% versus [35.61 +/- 5.61]%, [43.30 +/- 6.94]% and [69.01 +/- 4.98]%), WBC count ([1.72 +/- 0.37] x 10(9)/L, [1.23 +/- 0.27] x 10(9)/L and [0.86 +/- 0.25] x 10(9)/L versus [1.45 +/- 0.40] x 10(9)/L, [0.51 +/- 0.24] x 10(9)/L, [0.37 +/- 0.26] x 10(9)/L and [3.96 +/- 0.26] x 10(9)/L), PLT count ([1.18 +/- 0.11] x 10(11)/L, [0.97 +/- 0.10] x 10(11)/L and [0.72 +/- 0.11] x 10(11)/L versus [0.97 +/- 0.15] x 10(11)/L, [0.76 +/- 0.16] x 10(11)/L, [0.64 +/- 0.12] x 10(11)/L and [2.89 +/- 0.21] x 10(11)/L) and body weight ([18.60 +/- 0.66] g, [17.60 +/- 0.39] g and [16.90 +/- 0.68] g versus [17.86 +/- 0.60] g, [15.56 +/- 0.39] g, [14.61 +/- 0.65] g and [19.95 +/- 0.73] g) (P < 0.01).

CONCLUSIONIntratumoral implantation of 32P-CP-PL-LA is a safe, simple and effective radionuclide interventional therapy for prostate cancer.