Cryosurgery of the monkey (macaque) prostate. I. Humoral immunologic responsiveness following cryostimulation

Non-extended cryoablation could be a new strategy in lung cancer management: An experiment on green fluorescent protein-labeled Lewis lung cancer-bearing mice

Modern cryoablation has been performed in solid tumor management for more than two decades. Following the surgical spirits, it seems natural to pursue radical procedures in clinical practice, which results in unnecessary adverse effects. The attempt to use non-extended procedure made some marked achievements in practice but was criticized severely, because it was supposed to induce residual tumors, which would trigger the rapid development of cancer. Oncologists favored this procedure, however, claiming that non-extended cryoablation let lung cancer patients have higher quality of lives and longer survivals, in light of clinical observations. Therefore, this study was conducted trying to solve this controversy. In this study, fifty female C57BL/6J mice were grafted green fluorescent protein (GFP)-labeled Lewis lung cancer and randomized into two groups. The bidirectional diameters and fluorescence intensity of tumors, and the body weight of mice were recorded. Two weeks after the intervention, tumor volumes increased 20.95% in the cryoablation group, significantly different from that in the control group; the fluorescence intensity decreased 49.85% in the cryoablation group but increased 125.07% in the control group. Lung metastases could be observed in only 20% of mice in the cryosurgery group, contrasted to 64% in the control group. The non-extended lung cancer cryoablation does induce marginal tumor residuals, but will not trigger rapid tumor development. Inversely, the residual tumor cells are severely struck and the metastases are suppressed after the intervention. It could be a new strategy in lung cancer management, even for patients not in early stage.

Thermal ablation of tumours: biological mechanisms and advances in therapy

Minimally invasive thermal ablation of tumours has become common since the advent of modern imaging. From the ablation of small, unresectable tumours to experimental therapies, percutaneous radiofrequency ablation, microwave ablation, cryoablation and irreversible electroporation have an increasing role in the treatment of solid neoplasms. This Opinion article examines the mechanisms of tumour cell death that are induced by the most common thermoablative techniques and discusses the rapidly developing areas of research in the field, including combinatorial ablation and immunotherapy, synergy with conventional chemotherapy and radiation, and the development of a new ablation modality in irreversible electroporation.

More than just tumor destruction: immunomodulation by thermal ablation of cancer

Over the past decades, thermoablative techniques for the therapy of localized tumors have gained importance in the treatment of patients not eligible for surgical resection. Anecdotal reports have described spontaneous distant tumor regression after thermal ablation, indicating a possible involvement of the immune system, hence an induction of antitumor immunity after thermoinduced therapy. In recent years, a growing body of evidence for modulation of both adaptive and innate immunity, as well as for the induction of danger signals through thermoablation, has emerged. Induced immune responses, however, are mostly weak and not sufficient for the complete eradication of established tumors or durable prevention of disease progression, and combination therapies with immunomodulating drugs are being evaluated with promising results. This article aims to summarize published findings on immune modulation through radiofrequency ablation, cryoablation, microwave ablation therapy, high-intensity focused ultrasound, and laser-induced thermotherapy.

Cryo-immunology: a review of the literature and proposed mechanisms for stimulatory versus suppressive immune responses

The use of cryosurgery to ablate tumors is expanding, primarily due to its technical ease and minimal morbidity. A potential secondary advantage to the in situ freezing of malignant disease is the cryo-immunologic response, the generation of an anti-tumor immune response triggered by the natural absorption of the malignant tissue. While initially proposed based on clinical observations of distant disease regressing after cryoablation of a primary tumor, results from preclinical studies have been mixed and the existence of a cryo-immunologic response has been controversial. Recent studies have shed light on the potential mechanism by which cryoablation may modulate the immune system, also reveals that both immunostimulatory and immunosuppressive responses may be triggered. This article reviews the existing evidence regarding tumor cryo-immunology and puts forward hypotheses regarding patient, tumor and technical factors that may influence the resultant immune response and warrant further investigation.

Immunologic and morphologic effects of cryosurgery of the monkey (macaque) prostate

A reduction in size of the Macaque prostate following single and multiple in situ freezings was accompanied by histologic alterations, which occurred predominately in the caudal lobe and were characterized by what appeared to be specific periacinar foci of lymphocytic infiltrates. These lymphocytes were observed to infiltrate onto acinar epithelial cells, resulting in their subsequent separation from the basal lamina and epithelial destruction. Other histologic alterations were in consonance with studies of the prostate following cryosurgery by others. Circulating antibodies specific for prostate were present in only one of the seven animals at the time at which these histologic observations were made. These observations suggest the possible development of a cellular immunologic response following cryosurgery of the prostate. The relevancy of these observations to those obtained following cryoprostatectomy in man and other species is considered. Pending confirmation, they may be of potential significance in providing an explanation of reported cases of eradication of human prostatic carcinomas following cryotherapy.

The cryobiological basis for cryosurgery

This paper discusses two important biological factors contributing to the death of cells within any region that is frozen cryosurgically. The first factor is the relationship between cell death and the thermal history experienced by each cell. Freezing with a single probe as usually done cannot provide sufficiently uniform conditions of cooling and warming to ensure widespread cell death. This situation can be improved by cycling a single probe at subzero temperatures or by the use of a multiple probe. The second factor is that of possible immunological responses induced by cryosurgical freezing. Improvements in understanding of biological implications of low temperatures in cryosurgery will aid the practical usefulness of these techniques.