[Local ablative radiotherapy of oligometastatic colorectal cancer]

Activation of M2 macrophage autophagy by rapamycin increases the radiosensitivity of colorectal cancer xenografts

BACKGROUND

Tumor-associated macrophages (TAMs) are intimately involved in cancer radiochemotherapy resistance. However, the mechanism by which macrophages affect radiosensitivity through autophagy remains unclear. The purpose of our study was to investigate how activating autophagy in type-II macrophages (M2) by using rapamycin (RAP) would affect the radiosensitivity of colorectal cancer (CRC) xenografts.

MATERIALS AND METHODS

A nude mouse CRC model was established by injecting LoVo CRC cells. After tumor formation, supernatant from M2 cells (autophagy-unactivated), autophagy-activated M2 cells, or autophagy-downregulated M2 cells was injected peritumorally. All tumor-bearing mice were irradiated with 8-Gy X-rays twice, and the radiosensitivity of CRC xenografts was analyzed in each group.

RESULTS

The mass, volume, and microvessel density (MVD) of tumors in the autophagy-unactivated M2 group significantly increased; however, supernatant from M2 cells that were autophagy-activated by rapamycin significantly decreased tumor weight, volume, and MVD compared with negative control. Combining bafilomycin A1 (BAF-A1) with RAP treatment restored the ability of the M2 supernatant to increase tumor mass, volume, and MVD. Immunohistochemical and Western blot results showed that compared with the negative control group, supernatant from M2 cells that were not activated by autophagy downregulated the expression of Livin and Survivin in tumor tissues; activation of M2 autophagy further downregulated the protein levels.

CONCLUSIONS

Therefore, autophagy-activated M2 supernatant can downregulate the expression of the antiapoptotic genes Livin and Survivin in CRC xenografts, improving the radiosensitivity of CRC by inducing apoptosis in combination with radiotherapy and inhibiting the growth of transplanted tumors.

[What does the general and abdominal surgeon need to know about oncologically oriented radiotherapy?]

BACKGROUND

Radiotherapy is an integral component of most modern multimodal tumor treatment concepts, both in palliative and curative situations and intentions. This also applies to many tumor entities relevant in general as well as abdominal surgery. This can give rise to new challenges in the context of the daily clinical routine and interdisciplinary tumor conferences.

AIM

Practice relevant overview, based on selective references from the current scientific literature in medicine and own experiences obtained in daily work, for the oncological surgeon on radiotherapy-associated options for visceral tumor lesions. A particular focus is on rectal cancer, esophageal cancer, anal cancer and liver metastases.

METHOD

A narrative review is given.

RESULTS (SELECTED CORNER POINTS)

In total neoadjuvant therapy it is possible to avoid resection in rectal cancer if a good response is achieved and close monitoring can be provided. In esophageal cancer neoadjuvant chemoradiotherapy followed by resection can be considered the therapeutic regimen of choice for all suitable patients. If surgery is not an option, definitive chemoradiotherapy is an appropriate and favorable alternative, especially with respect to squamous cell carcinoma. Even taking the latest data on the topic into account, definitive chemoradiotherapy remains undisputedly recommended for anal cancer. Liver tumors can be locally ablated by stereotactic radiotherapy.

CONCLUSION

Close cooperation between disciplines in the context of tumor therapy remains essential for the best possible treatment and outcome of patients.

Cost-Effectiveness Analysis of Local Ablation and Surgery for Liver Metastases of Oligometastatic Colorectal Cancer

BACKGROUND

Colorectal cancer is among the most prevalent cancer entities worldwide, with every second patient developing liver metastases during their illness. For local treatment of liver metastases, a surgical approach as well as ablative treatment options, such as microwave ablation (MWA) and radiofrequency ablation (RFA), are available. The aim of this study is to evaluate the cost-effectiveness of RFA, MWA and surgery in the treatment of liver metastases of oligometastatic colorectal cancer (omCRC) that are amenable for all investigated treatment modalities.

METHODS

A decision analysis based on a Markov model assessed lifetime costs and quality-adjusted life years (QALY) related to the treatment strategies RFA, MWA and surgical resection. Input parameters were based on the best available and most recent evidence. Probabilistic sensitivity analyses (PSA) were performed with Monte Carlo simulations to evaluate model robustness. The percentage of cost-effective iterations was determined for different willingness-to-pay (WTP) thresholds.

RESULTS

The base-case analysis showed that surgery led to higher long-term costs compared to RFA and MWA (USD 41,848 vs. USD 36,937 vs. USD 35,234), while providing better long-term outcomes than RFA, yet slightly lower than MWA (6.80 vs. 6.30 vs. 6.95 QALYs for surgery, RFA and MWA, respectively). In PSA, MWA was the most cost-effective strategy for all WTP thresholds below USD 80,000 per QALY.

CONCLUSIONS

In omCRC patients with liver metastases, MWA and surgery are estimated to provide comparable efficacy. MWA was identified as the most cost-effective strategy in intermediate resource settings and should be considered as an alternative to surgery in high resource settings.

Local treatment of oligometastatic disease: current role

The presence of distant metastases has long been a predictor of poor outcome in solid cancer. However, in an oncologic situation called oligometastatic disease (OMD), multiple studies have revealed a survival benefit with aggressive treatment of these metastases. Besides surgery and radiation therapy, local thermal therapies have developed into a treatment option for OMD. Most studies concerning local therapy of OMD are available for colorectal cancer, which is therefore the focus of this article. Furthermore, this review gives a basic overview of the most popular ablation techniques for treatment of OMD.

Outcomes after hypofractionated stereotactic radiotherapy for colorectal cancer oligometastases

BACKGROUND AND OBJECTIVES

To assess the efficacy and the effect of biologic effective dose (BED) on outcomes treated by hypofractionated stereotactic radiotherapy for colorectal cancer (CRC) oligometastases.

METHODS

Patients with CRC oligometastases treated at our hospital between 2009 and 2016 were included. The relationship between BED and risk of local recurrence was assessed. Recursive partitioning analysis (RPA) was used to evaluate the effect of BED on outcomes.

RESULTS

A total of 48 patients were included in this study. Median follow-up time of surviving patient was 15 months (range, 3-82 months). The 1-year local control rate was 85%. The risk of local recurrence decreased sharply when BED was >90 Gy10 . RPA showed BED of 100 Gy 10 was the appropriate dose for recurrence risk stratification. BED ≥ 100 Gy 10 was significantly better than BED < 100 Gy 10 for achieving 1-year local control (94.4% vs 63.2%; P = 0.022) and 1-year OS (100% vs 73.4%; P = 0.028). One patient who received long-term antiangiogenic treatment died of massive intestinal hemorrhage; no other grade 3 or above early or late events were observed.

CONCLUSIONS

Hypofractionated stereotactic radiotherapy provides favorable outcomes with acceptable toxicities in CRC oligometastases. BED ≥ 100 Gy is associated with better outcomes.

[Oligometastasized colorectal cancer-modern treatment strategies]

BACKGROUND

The prognosis of colorectal cancer in UICC stage IV has been improved in the last decades by improvements in interdisciplinary treatment.

MATERIAL AND METHODS

Treatment strategies for oligometastasized colorectal cancer are developing more and more into an individualized treatment. An overview of the current literature of modern treatment concepts in oligometastasized colorectal cancer UICC stage IV is given.

RESULTS

Surgery still has the supreme mandate in resectable colorectal liver metastases, as neoadjuvant and adjuvant treatment strategies to not provide any benefits for these patients. In marginal or non-resectable stages systemic treatment is superior in these patients depending on the prognostic parameters. Also in curative settings local treatment options should be considered as a reasonable additive tool. An interesting treatment approach for isolated liver metastases and non-resectable colorectal cancer is liver transplantation.

CONCLUSION

Irrespective of new developments in treatment strategies for metastasized colorectal cancer, resection of colorectal liver metastases remains the gold standard whenever possible.