Researchers in Japan conducted a study to evaluate whether antitumor immunity is enhanced systemically by combining radiofrequency ablation (RFA) and local injection of an immunostimulant, OK-432. Rabbits were inoculated with VX2 tumors in the lung and the auricle were randomized into four groups of eight: control (supportive care), RFA (RFA of lung tumor), OK-432 (direct injection of OK-432 into lung tumor), and combination therapy (lung RFA and direct OK-432 injection into lung tumor). All procedures were performed one week after implantation of VX2 tumors (week one). In addition, a VX2 tumor rechallenge text was done in the RFA and combination therapy groups. Survival time was evaluated by means of the Kaplan-Meier method any using the log-rank test for intergroup comparison. The median survival times of the control, RFA, OK-432, and combination therapy groups were 23, 36.5, 46.5, and 105 days, respectively. Survival times were significantly prolonged in the combination therapy group when compared with the other three groups. The researchers conclude that combining RFA with local injection of immunostimulant OK-432 may lead to indirectly activation of systemic antitumor immunity.
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Radiology (03/01/13) Hamamoto, Shinichi; Okuma, Tomohisa; Yamamoto, Akira; et al.