Objective: The possibility that cryosurgery may stimulate certain aspects of the immune system in humans producing anti-neoplastic responses has been postulated for some time. Our particular interest is in the treatment of endobronchial tumours with cryotherapy and observing that following cryotherapy; the incidence of supraclavicular node enlargement during the progression of advanced bronchial carcinoma was only 4%. This led us to investigate the possibility of changes in immunological parameters in peripheral blood of cryotreated patients.
Methods: Here, we present the findings of a prospective clinical study of 14 patients (mean age 65.5 years, range 35 - 86 years, Male: female ratio, 10:4) undergoing endobronchial cryotherapy for obstructive tumours of the airway. Histological composition was 9 squamous cell, 2 adencarcinoma, I undifferentiated carcinoma, and 2 carcinoid tumours. The levels of a range of immunological phenotypes obtained from peripheral blood were measured at several intervals prior to and following up to three sessions of cryotherapy.
Results: A paired two-tail t-test analysis of the population data showed there was a significant (p<0.05) fall in total lymphocyte, CD3, CD16/56 (NK cells) and CD8 counts two weeks after the second cryotherapy session compared to preoperative levels. These changes appear sustained in the longer term with some further falls. A similar fall occurred in CD8 and CD8 dim levels after the first session of cryotherapy. CD4 and CD3 levels were stimulated early on after the first session of cryotherapy but then fell after the second session. Significant changes were also observed in monocytes and NK cells (CD3, CD16/56) which fell after the second treatment, CD3/DR which were stimulated after the third treatment, and CD57 levels which fell after the third treatment.
Conclusion: We suggest that endobronchial cryotherapy may cause changes in certain aspects of the immune response to disease. This change in the cell phenotypes observed in the peripheral blood may be due to an increase in tumour infiltration by the circulating lymphocytes.