Can surgery for cancer accelerate the progression of secondary tumors within residual minimal disease at both local and systemic levels?

The relevance of liquid biopsy in surgical oncology: The application of perioperative circulating nucleic acid dynamics in improving patient outcomes

BACKGROUND

Liquid biopsy is gaining increasing clinical utility in the management of cancer patients. The main components of a liquid biopsy are circulating nucleic acids, circulating tumour cells and extracellular vesicles such as exosomes. Circulating nucleic acids including cell free DNA (cfDNA) and circulating tumour DNA (ctDNA) in particular have been the focus of recent attention as they have demonstrated excellent potential in cancer screening, provision of prognostic information and in genomic profiling of a tumour without the need for repeated tissue biopsies. The aim of this review was to explore the current evidence in relation to the use of liquid biopsy in the perioperative setting and identify ways in which liquid biopsy may be applied in the future.

METHODS

This narrative review is based on a comprehensive literature search up to the 1st of June 2020 for papers relevant to the application of liquid biopsy in surgical oncology, focusing particularly on the perioperative period.

RESULTS

Recent evidence has demonstrated that perioperative liquid biopsy can accurately stratify patients' risk of recurrence compared to conventional biomarkers. Attention to the perioperative dynamics of liquid biopsy components can potentially provide new understanding of the complex relationship between surgery and cancer outcome. In addition, careful evaluation of liquid biopsy components in the perioperative window may provide important diagnostic and therapeutic information for cancer patients.

CONCLUSION

The rapidly evolving concept of the liquid biopsy has the potential to become the cornerstone for decision making around surveillance and adjuvant therapies the era of personalised medicine.

Neuroimmune Regulation of Surgery-Associated Metastases

Surgery remains an essential therapeutic approach for most solid malignancies. Although for more than a century accumulating clinical and experimental data have indicated that surgical procedures themselves may promote the appearance and progression of recurrent and metastatic lesions, only in recent years has renewed interest been taken in the mechanism by which metastasizing of cancer occurs following operative procedures. It is well proven now that surgery constitutes a risk factor for the promotion of pre-existing, possibly dormant micrometastases and the acceleration of new metastases through several mechanisms, including the release of neuroendocrine and stress hormones and wound healing pathway-associated immunosuppression, neovascularization, and tissue remodeling. These postoperative consequences synergistically facilitate the establishment of new metastases and the development of pre-existing micrometastases. While only in recent years the role of the peripheral nervous system has been recognized as another contributor to cancer development and metastasis, little is known about the contribution of tumor-associated neuronal and neuroglial elements in the metastatic disease related to surgical trauma and wound healing. Specifically, although numerous clinical and experimental data suggest that biopsy- and surgery-induced wound healing can promote survival and metastatic spread of residual and dormant malignant cells, the involvement of the tumor-associated neuroglial cells in the formation of metastases following tissue injury has not been well understood. Understanding the clinical significance and underlying mechanisms of neuroimmune regulation of surgery-associated metastasis will not only advance the field of neuro–immuno–oncology and contribute to basic science and translational oncology research but will also produce a strong foundation for developing novel mechanism-based therapeutic approaches that may protect patients against the oncologically adverse effects of primary tumor biopsy and excision.

RandomiSed clinical trial assessing Use of an anti-inflammatoRy aGent in attenUating peri-operatiVe inflAmmatioN in non-meTastatic colon cancer - the S.U.R.G.U.V.A.N.T. trial

Background

Peri-operative inflammation has been extensively highlighted in cancer patients as detrimental. Treatment strategies to improve survival for cancer patients through targeting peri-operative inflammation have yet to be devised.

Methods

We conducted a multi-centre, randomised controlled clinical trial using Taurolidine in non-metastatic colon cancer patients. Patients were randomly assigned to receive Taurolidine or a placebo. The primary endpoint for the study was the mean difference in day 1 IL-6 levels. Secondary clinical endpoints included rates of post-operative infections and tumor recurrence.

Results

A total of 293 patients were screened for trial inclusion. Sixty patients were randomised. Twenty-eight patients were randomised to placebo and 32 patients to Taurolidine. IL-6 levels were equivalent on day 1 post-operatively in both groups. However, IL-6 levels were significantly attenuated over the 7 day study period in the Taurolidine group compared to placebo (p = 0.04). In addition, IL-6 levels were significantly lower at day 7 in the Taurolidine group (p = 0.04). There were 2 recurrences in the placebo group at 2 years and 1 in the Taurolidine group. The median time to recurrence was 19 months in the Placebo group and 38 months in the Taurolidine group (p = 0.27). Surgical site infection was reduced in the Taurolidine treated group (p = 0.09).

Conclusion

Peri-operative use of Taurolidine significantly attenuated circulating IL-6 levels in the initial 7 day post-operative period in a safe manner. Future studies are required to establish the impact of IL-6 attenuation on survival outcomes in colon cancer.

Trial registration

The trial was registered with EudraCT (year = 2008, registration number = 005570–12) and ISRCTN (year = 2008, registration number = 77,829,558).

Abscopal Benefits of Localized Radiotherapy Depend on Activated T-cell Trafficking and Distribution between Metastatic Lesions

It remains unclear how localized radiotherapy for cancer metastases can occasionally elicit a systemic antitumor effect, known as the abscopal effect, but historically, it has been speculated to reflect the generation of a host immunotherapeutic response. The ability to purposefully and reliably induce abscopal effects in metastatic tumors could meet many unmet clinical needs. Here, we describe a mathematical model that incorporates physiologic information about T-cell trafficking to estimate the distribution of focal therapy-activated T cells between metastatic lesions. We integrated a dynamic model of tumor-immune interactions with systemic T-cell trafficking patterns to simulate the development of metastases. In virtual case studies, we found that the dissemination of activated T cells among multiple metastatic sites is complex and not intuitively predictable. Furthermore, we show that not all metastatic sites participate in systemic immune surveillance equally, and therefore the success in triggering the abscopal effect depends, at least in part, on which metastatic site is selected for localized therapy. Moreover, simulations revealed that seeding new metastatic sites may accelerate the growth of the primary tumor, because T-cell responses are partially diverted to the developing metastases, but the removal of the primary tumor can also favor the rapid growth of preexisting metastatic lesions. Collectively, our work provides the framework to prospectively identify anatomically defined focal therapy targets that are most likely to trigger an immune-mediated abscopal response and therefore may inform personalized treatment strategies in patients with metastatic disease.

Activation of latent metastases in the lung after resection of a metastatic lymph node in a lymph node metastasis mouse model

Iatrogenic induction of regional and distant cancer metastases is a risk associated with clinical resection of tumor-positive sentinel lymph nodes. However, there have been no studies of this risk in a mouse model of cancer metastasis. Here, we report that resection of a tumor-bearing subiliac lymph node (SiLN) enhanced lung metastasis in a mouse model of lymph node metastasis. Bioluminescence imaging revealed that metastatic tumor cells in the secondary lymph node continued to grow after resection of the SiLN, and that the probability of metastasis to the lungs was increased when the interval between SiLN inoculation and resection was reduced. Futhermore, histological analysis demonstrated that latents in the lung were stimulated to grow after resection of the SiLN. Fluorescence imaging indicated that the route of tumor cell dissemination from SiLN to the lung was the venous system located over the SiLN. We speculate that our mouse model will be useful for studying the mechanisms of tumor cell latency, with a view to improving the detection and treatment of latent metastases.

Caught in the act: revealing the metastatic process by live imaging

The prognosis of metastatic cancer in patients is poor. Interfering with metastatic spread is therefore important for achieving better survival from cancer. Metastatic disease is established through a series of steps, including breaching of the basement membrane, intravasation and survival in lymphatic or blood vessels, extravasation, and growth at distant sites. Yet, although we know the steps involved in metastasis, the cellular and molecular mechanisms of dissemination and colonization of distant organs are incompletely understood. Here, we review the important insights into the metastatic process that have been gained specifically through the use of imaging technologies in murine, chicken embryo and zebrafish model systems, including high-resolution two-photon microscopy and bioluminescence. We further discuss how imaging technologies are beginning to allow researchers to address the role of regional activation of specific molecular pathways in the metastatic process. These technologies are shedding light, literally, on almost every step of the metastatic process, particularly with regards to the dynamics and plasticity of the disseminating cancer cells and the active participation of the microenvironment in the processes.

Concomitant tumor resistance

Concomitant tumor resistance (CR) is a phenomenon in which a tumor-bearing host is resistant to the growth of secondary tumor implants. This phenomenon has been described in human and animal systems and it can be generated by both immunogenic and non-immunogenic tumors. The relevance of CR to the mechanisms of metastases control has been highlighted by numerous observations showing that the removal of human and murine tumors may be followed by an abrupt increase in metastatic growth, suggesting that a primary tumor may exert a controlling action on its metastases which could be considered as secondary tumor implants developed spontaneously during the primary tumor growth. A more profound understanding of the different mechanisms claimed to be associated with the phenomenon of CR could contribute to develop new and more harmless means to manage malignant diseases, especially by limiting the development of metastases that arise after resection of primary tumors or after other stressors that may promote the escape of metastases from dormancy.

Ginsenoside Rg3 inhibits growth of liver metastases in nude mice after surgical removal of primary tumor

AIM: To investigate the effect of 20(R)-Ginsenoside Rg3 on the growth of hepatic metastasis in nude mice after surgical removal of primary tumor.

METHODS: BALB/c mouse colon adenocarcinoma CT-26-GFP cell line was established by transfection of CT-26 cells with a lentiviral vector containing the enhanced green fluorescent protein (eGFP) gene. A nude mouse model of hepatic metastasis was then developed, and the mice were randomly divided into three groups: primary tumor resection group, primary tumor preservation group and Ginsenoside Rg3 group. After resection of the primary tumor and treatment with Ginsenoside Rg3 for 10 days, microvascular density (MVD) and cell multiplication of liver metastases were detected by immunohistochemistry, and tumor apoptosis was detected by TUNEL assay. The green fluorescence was observed using a fluorescence in vivo imaging system.

RESULTS: The average fluorescence intensity of liver metastases in the Ginsenoside Rg3 group was significantly lower than that in the primary tumor preservation group and primary tumor resection group (314.17 ± 54.23 vs 388.82 ± 25.97, 427.18 ± 44.31). The incidences of metastases in the Ginsenoside Rg3 group, primary tumor preservation group and primary tumor resection group were 40%, 50% and 100%, respectively. The average weight of the liver, MVD, and labeling index of Ki67 were lower and TUNEL apoptotic index was higher in the Ginsenoside Rg3 group than in the primary tumor preservation group and primary tumor resection group (liver weight: 2.92 ± 0.60 vs 3.80 ± 0.33, 3.98 ± 0.52; MVD: 27.10 ± 3.41 vs 42.60 ± 8.42, 62.40 ± 5.08; labeling index of Ki67: 34.70 ± 6.46 vs 54.30 ± 8.98, 65.20 ± 3.82; apoptotic index: 28.37 ± 3.86 vs 12.50 ± 2.99, 9.90 ± 2.88).

CONCLUSION: 20(R)-Ginsenoside-Rg3 could inhibit metastatic tumor growth, angiogenesis, proliferation and promote apoptosis in mice after surgical removal of primary tumor.

Concomitant tumor resistance: the role of tyrosine isomers in the mechanisms of metastases control

Concomitant tumor resistance (CR) is a phenomenon in which a tumor-bearing host is resistant to the growth of secondary tumor implants and metastasis. Although previous studies indicated that T-cell-dependent processes mediate CR in hosts bearing immunogenic small tumors, manifestations of CR induced by immunogenic and nonimmunogenic large tumors have been associated with an elusive serum factor. In a recently published study, we identified this factor as meta-tyrosine and ortho-tyrosine, 2 isomers of tyrosine that would not be present in normal proteins. In 3 different murine models of cancer that generate CR, both meta- and ortho-tyrosine inhibited tumor growth. Additionally, we showed that both isoforms of tyrosine blocked metastasis in a fourth model that does not generate CR but is sensitive to CR induced by other tumors. Mechanistic studies showed that the antitumor effects of the tyrosine isomers were mediated in part by early inhibition of the MAP/ERK pathway and inactivation of STAT3, potentially driving tumor cells into a state of dormancy in G(0)-phase. Other mechanisms, putatively involving the activation of an intra-S-phase checkpoint, would also inhibit tumor proliferation by accumulating cells in S-phase. By revealing a molecular basis for the classical phenomenon of CR, our findings may stimulate new generalized approaches to limit the development of metastases that arise after resection of primary tumors or after other stressors that may promote the escape of metastases from dormancy, an issue that is of pivotal importance to oncologists and their patients.

Prevention of local tumor recurrence following surgery using low-dose chemotherapeutic polymer films

AIM

To evaluate the efficacy of a polymer film designed for prolonged paclitaxel release at surgical margins to prevent local recurrence in non-small-cell lung cancer (NSCLC) following complete surgical resection in a murine model.

METHODS

Poly(glycerol monostearate co-epsilon-caprolactone) polymer films were prepared with or without 10% (w/w) paclitaxel and characterized for prolonged tumor cytotoxicity in vitro against several NSCLC cell lines including LLC, NCI-H460, and NCI-H292. Films were implanted following complete LLC tumor resection and assessed in vivo for prevention of local tumor recurrence, impact on wound healing, and extent of local drug delivery. Plasma and local tissue concentrations of paclitaxel were compared following systemic administration and film implantation.

RESULTS

The flexible polymeric films eluted paclitaxel over several weeks and remained cytotoxic to LLC, NCI-H460, and NCI-H292 cells in vitro for 50 days, while unloaded films did not impair tumor cell growth. Implanted paclitaxel films prevented local tumor recurrence in vivo in 83.3% of animals, compared with unloaded films (12.5%), systemic (22.2%) or locally administered paclitaxel (0%) (P < 0.005). Although minimal paclitaxel remained in either plasma or tissue 10 days after systemic injection, local paclitaxel concentration at the site of surgical resection was significantly greater (3,000-fold) at 10 days when paclitaxel was locally delivered via films (P = 0.024).

CONCLUSIONS

Local application of paclitaxel-loaded polymer films following surgical resection can prevent local tumor recurrence without impairing wound healing.

Metastasis progression is a clonally selective process on whole-body level

There is an argument about the metastatic progression. Not even one model can perfectly interpret the new results in cancer metastasis research. Cancer cells spread early from the primary site and give rise to metastasis. Logically, cancer cells may depart from the metastatic site early and reseed into the primary cancer. If the cells can migrate between the primary cite and the metastatic sites, plus adequate time, finally the clone with most selective advantage would dominate the primary and metastatic sites. Therefore, we surmise that the metastasis progression is a clonally selective process on whole-body level. Therapeutic attempts to better control cancer metastasis should therefore consider the interaction of primary and metastatic cancer.

Characterization of the Effects of Cyclooxygenase-2 Inhibition in the Regulation of Apoptosis in Human Small and Non–Small Cell Lung Cancer Cell Lines

BACKGROUND

Cyclooxygenase-2 enzyme (COX-2) is overexpressed in human non-small cell lung cancer (NSCLC) but is not expressed in small cell lung cancer. Selective COX-2 inhibitors have been shown to induce apoptosis in NSCLC cells, an effect which is associated with the regulation of intracellular MAP kinase (MAPK) signal pathways. Our aims were to characterize the effects of COX-2 inhibition by rofecoxib on apoptosis in human NSCLC and small cell lung cancer cell lines.

METHODS

The human NSCLC cell line NCI-H2126 and small cell lung cancer cell line DMS-79 were used. Constitutive COX-2 protein levels were first determined by Western blot test. Levels of apoptosis were evaluated by using propidium iodide staining on FACScan analysis after incubation of NCI-H2126 and DMS-79 with p38 MAPK inhibitor SB202190 (25 ?microM), NF-kappaB inhibitor SN50 (75 microg/mL), and rofecoxib at 100 and 250 microM. All statistical analysis was performed by analysis of variance.

RESULTS

Western blot test confirmed the presence of COX-2 enzyme in NCI-H2126 and absence in DMS-79. Interestingly, rofecoxib treatment demonstrated a dose-dependent increase in apoptosis in both cell lines. Given this finding, the effect of rofecoxib on NF-kappaB and p38 MAPK pathways was also examined. Apoptosis in both cell lines was unaltered by SN50, either alone or in combination with rofecoxib. A similar phenomenon was observed in NCI-H2126 cells treated with SB202190, either alone or in combination with rofecoxib. In contrast, p38 MAPK inhibition greatly upregulated DMS-79 apoptosis in a manner that was unaltered by the addition of rofecoxib.

CONCLUSIONS

Rofecoxib led to a dose-dependent increase in apoptosis in both tumor cell lines. This effect occurred independently of COX-2, NF-kappaB, and p38 MAPK pathways in DMS-79 cells. As such, rofecoxib must act on alternative pathways to regulate apoptosis in human small cell lung cancer cells.