INFLUENCE OF SURGICAL PROCEDURES ON DEVELOPMENT OF SPONTANEOUS LUNG METASTASES

Surgical Treatment of Osteosarcoma Induced Distant Pre-Metastatic Niche in Lung to Facilitate the Colonization of Circulating Tumor Cells

Recently, the major challenge in treating osteosarcoma patients is the metastatic disease, most commonly in the lungs. However, the underlying mechanism of recurrence and metastasis of osteosarcoma after surgical resection of primary tumor remains unclear. This study aims to investigate whether the pulmonary metastases characteristic of osteosarcoma is associated with surgical treatment and whether surgery contributes to the formation of pre-metastatic niche in the distant lung tissue. In the current study, the authors observe the presence of circulating tumor cells in patients undergoing surgical resection of osteosarcoma which is correlated to tumor recurrence. The pulmonary infiltrations of neutrophils and Gr-1+ myeloid cells are characterized to form a pre-metastatic niche upon the exposure of circulating tumor cells after surgical resection. It is found that mitochondrial damage-associated molecular patterns released from surgical resection contribute to the formation of pre-metastatic niche in lung through IL-1β secretion. This study reveals that surgical management for osteosarcoma, irrespective of the primary tumor, might promote the formation of postoperative pre-metastatic niche in lung which is with important implications for developing rational therapies during peri-operative period.

Discovery of candidate genes and pathways that may help explain fertility cycle stage dependent post-resection breast cancer outcome

Breast cancer relapse and death occur more often and sooner among young pre-menopausal women. Breast cancer resected during luteal phase cures about a quarter more women than if the operation is performed during follicular phase. We have identified candidate breast cancer gene signatures that may point to the potential mechanisms of cycle stage-dependent surgical cure. We performed whole murine genome microarrays on mammary tumors resected during pre-ovulatory (diestrus, follicular) and post-ovulatory (estrus, luteal) phases of the estrous cycle with known post-surgical cure or relapse (pulmonary metastasis) outcome. A set of genes whose expressions are differentially modulated by fertility cycle stage of tumor resection and also associate with prognosis were identified. These identified genes were validated by qRT-PCR. From two independent microarray studies, we identified 90 genes in mammary tumors whose expressions change significantly (up to 100-fold) across the estrous cycle, 69 genes that are associated with cure/relapse independent of cycle stage at resection, and 24 genes that change significantly (up to 12-fold) across the estrous cycle and also associate with the outcome. The mRNA expression patterns of these 24 identified genes were 100% validated by qRT-PCR in the same samples. We have identified candidate breast cancer genes and pathways that may point to the potential mechanisms by which the post-resection breast cancer outcome is influenced by the menstrual cycle phase of cancer resection. Since human breast cancer outcome is influenced by the menstrual cycle phase of breast cancer resection, we consider this study in a mouse breast cancer model to be a proof of principle that such signatures may well exist in human premenopausal breast cancer. It remains to be determined in human breast cancer whether woman to woman and/or tumor to tumor variability will mask cycle phase dependent and outcome predictive genomic signatures in human premenopausal breast cancer. The pathways identified by these studies are potential targets for the development of peri-surgical neoadjuvant therapies, which may delay or prevent relapse by preventing dormant micrometastatic tumor cells from escaping that dormant state post-operatively.

Proliferative response of human prostate tumour xenografts to surgical trauma and the transurethral resection of the prostate controversy

Transurethral resection of the prostate (TURP) as an excisional procedure involving multiple incisions into the prostate does not differentiate between palpably benign prostate tissue and microscopic foci of well-differentiated adenocarcinoma. The impact of TURP on the progression of such 'latent' or 'incidental' tumours unique to the prostate gland has been a focal point of a continuing controversy. In studies designed to develop preclinical evidence that would lend support to, or detract from, either side of the TURP controversy, surgical trauma-induced stimulation of in situ tumour growth was extended to include human prostate tumour tissue PC-3, DU-145 and H-1579, albeit as xenografts in athymic nude males. A significant proliferative response of prostate tumours implanted directly in, adjacent to, or distant from, a freshly induced surgical wound, could be inhibited by a somatostatin analogue (Lanreotide) applied topically to the surgical site. This preclinical model supports TURP as a risk factor for biopsy or therapeutic surgical intervention procedures in benign prostatic hypertrophy (BPH), a risk factor that increases with the stage of disease in undetected cancers. It also suggests a potential clinical benefit that might be derived by applying Lanreotide directly to the surgically traumatised genitourinary area by simple irrigation of the urethra and bladder during or shortly post TURP.

The influence of cytoreductive surgery on the response to chemotherapy of a rat renal cancer

The potential ability of cytoreductive surgery to increase the effectiveness of chemotherapy (vindesine) was tested utilizing male Wistar Lewis rats transplanted simultaneously with intraperitoneal and flank implants of a spontaneously arising renal adenocarcinoma. Cytoreduction was accomplished in some animals by removing the flank tumor 5-7 weeks following implantation; all animals received vindesine (IP injection of 0.5 mg/kg on two successive weeks). While vindesine reduced tumor growth, in no case did the addition of cytoreductive surgery enhance the effect of chemotherapy. The addition of cytoreductive surgery to marginally effective chemotherapy was found to be ineffective or even detrimental.

Surgery, trauma and immune suppression. Evolving the mechanism

A major surgical procedure can impair the delayed hypersensitivity response. This impairment is associated with suppressor cell activity that can alter either afferent or efferent responses. Using the third party mixed leukocyte culture to define cell types involved, major immune impairment was seen with the combination of both nonadherent and plastic adherent cells, suggesting that a T cell-macrophage interaction is required. A serum factor(s) is present in operated mice that can impair mixed leukocyte culture reactivity. A serum factor(s) in an adoptive transfer experiment is also capable of enhancing primary tumor growth. A unifying hypothesis, based predominantly on data from the current literature, is presented in an attempt to elucidate the mechanism by which all forms of major trauma are associated in some patients with "paradoxical" immune suppression.

Divergency between incidence of microscopic and macroscopic metastases

In a rat fibrosarcoma model (D-12), the incidence of macroscopic metastases was generally low but critically dependent on the site of the primary tumor implant; surgical removal of the primary tumor either induced or markedly enhanced the outgrowth of macroscopic metastases (Keller 1981). The present histological and biological findings indicate that dissemination of neoplastic cells and colonization of draining lymph nodes is a spontaneous, early occurring and continuing process. The incidence of micrometastases within lymph nodes by far exceeded the incidence of macroscopically evident metastases. Other evidence suggests that the growth characteristics of D-12 tumor cells derived from metastases are not measurably different from D-12 cells inducing primary tumor growth.

A model of tumor cell dormancy: effects of anesthesia and surgery

Three cloned populations of tumor cells obtained from a murine fibrosarcoma were able to remain viable for a long period of time in syngeneic mice which failed to exhibit clinically evident tumors following tumor cell inoculation. Viable tumor cells under such conditions can be considered to be in a dormant state. On the basis of past studies, two of the lines were shown to have low malignant potential, while the third line was shown to have a higher degree of malignant potential. The rates of spontaneous reactivation of tumor growth in animals carrying the low malignant cells were 3 and 4%, while a rate of 30% was observed in animals with the more malignant cells. Treatment of animals carrying the low malignant cells in a dormant state with anesthesia alone, (thiopental) or with anethesia and surgery, increased the rate of reactivation to 20-22%.

Suppressive effects of thiopental and halothane on specific arms of the immune response

The effect of thiopental, halothane and surgery on specific arms of the immune response of normal mice was studied. These experiments represent the first step in localizing a potentially correctable anesthesia/surgery-induced defect in immune reactivity which may be involved with postoperative increases in tumor growth. The delayed-type hypersensitivity (DTH) response of mice to 2,4-dinitrochlorobenzene (DNCB) was studied. Combinations of induction and inhalation anesthesia and surgery were administered at various phases of the immune response to DNCB. Thiopental impaired the afferent response while halothane impaired the efferent response. When the agents were combined, both arms of the immune response were suppressed. A surgical procedure, in most experiments, did not produce a greater immunosuppression than thiopental and halothane. The administration of an immunorestorative agent, thiabendazole, returned reactivity to normal levels. Thiopental and halothane either affect different immune cell populations or they affect different functions of a cell population active in both arms of the DTH response. In relation to tumor growth, the degree of suppression may not be as significant as the cell population impaired.

Immune impairment and metastatic tumor growth: the need for an immunorestorative drug as an adjunct to surgery

A spontaneous murine metastatic tumor system was used as a model to assess the effects of a major surgical procedure on tumor-specific immune reactivity and the growth of micrometastases. Any major surgical procedure resulted in impaired cell-mediated cytotoxicity postoperatively and an increase in the number of gross pulmonary metastases. The use of an immunorestorative drug, Thiabendazole, in the perioperative period resulted in an improved cytotoxic response and a significant decrease in pulmonary metastases. Perioperative immunotherapy can be an effective adjunct to surgery in preventing the growth of micrometastatic foci.

Effect of anesthesia and surgery on immunity

The observed phenomenon that multiple distant metastases may appear and grow rapidly after operation on the primary cancer is very distressing. Many experimental results suggest that surgical procedures may precipitate dissemination and growth of tumor in some instances, but the overwhelming evidences document that surgical reduction of tumor bulk can achieve cure for the host and restore the immunity lost in the face of growing tumors. Various anesthetics were shown to interfere with many phases of the immune response. But recent studies suggest that the inhibitory effect of anesthesia alone is minimal. Depression of lymphocyte transformation, detectable as early as 2 hours after induction, was related primarily to the extent of tissue trauma, the amount of blood loss, duration of operation, and whether thoracic or abdominal cavity was entered. Posoperative changes of lymphocyte counts and transformation responses usually returned to normal values within a week, whereas depression of specific cellular immunity to tumor-associated antigen in vitro, and delayed cutaneous hypersensitivity reactions in vivo, persisted for about a week and gradually returned to normal by 3 weeks. Presently the clinical significance of such transitory depression of host immunity is not known. It is hoped that this review may stimulate interest in further experimental and clinical research.