[Development of an experimental model for the study of the effects of cryotherapy on lung tumours].

Unlabelled: Adenocarcinomas are today the most frequent lung cancers. They are mainly treated by surgery or by chemotherapy, but for the most advanced stages a local cryotherapy can be proposed as a palliative option for bronchial desobstruction.

Aim Of The Study: The aim of this work was to establish an experimental model to study in vivo the biological effects of this technique to propose it as a neoadjuvant treatment.

Materials And Methods: A xenograft system was used: cells from the A549 cell line were injected subcutaneously into SCID mice. Tumour nodes could be treated after seven weeks. The histological study showed that these tumours faithfully reproduced the morphological features of adenocarcinoma, and developed an intratumoral neovascularization. Two protocols of cryotherapy (1 vs 3 cycles of freezing) were performed and the induction of apoptosis was analyzed by immunohistochemical staining of cleaved caspase-3.

Results: The basal expression of cleaved caspase-3 in untreated tumours (23%) increased after cryotherapy. The increase was maximal eight hours after treatment (up to 47% of positive cells) and was less important with the first protocol, suggesting a lesser efficiency in the induction of apoptosis.

Conclusion: The establishment of this model, which is faithful to physiological features, allowed us to demonstrate in vivo time and dose-dependent effects of cryotherapy.