Conductive interstitial thermal therapy (CITT) inhibits recurrence and metastasis in rabbit VX2 carcinoma model

To investigate the potential of conductive interstitial thermal therapy (CITT) to inhibit recurrence and metastasis in a partially resected tumour model.

Fifteen New Zealand white rabbits were implanted with VX2 tumour intramuscularly in the rear thigh. Once the tumour size reached 20-25 mm in diameter, three animals were randomly selected to serve as controls, while the remaining animals were designated as the study group and treated with CITT. In the CITT group, the partially resected tumour and margins were thermally ablated. In the control group the tumour was partially resected to simulate positive margins. The animals were monitored for up to 12 weeks. At the endpoint, the animals were sacrificed, and whole-body diagnostic necropsy was conducted immediately.

Recurrences and metastatic lesions were observed in iliac and popliteal lymph nodes and abdomens of all control animals. In contrast, the observed rate of recurrence and metastatic lesion was 0% among CITT-treated animals, significantly less than the >or=50% null-hypothesis rate expected upon treatment failure (exact binomial P = 0.0002). Complete histopathological healing was obtained in 2 of 12 rabbits, and residual inflammation remained at the ablation site up to 12 weeks post-ablation in 10 of 12 rabbits. This pattern of necrosis and inflammatory response was not observed in any of the control rabbits.

The CITT device effectively ablated partially resected VX2 carcinoma in a rabbit model, and inhibited recurrence and metastasis in this model. CITT evoked an inflammatory response that may be linked to the mechanism involved in reduced metastatic spread.