Locoregional treatments of unresectable liver metastases from colorectal cancer

A Computational Study on Magnetic Nanoparticles Hyperthermia of Ellipsoidal Tumors

The modelling of magnetic hyperthermia using nanoparticles of ellipsoid tumor shapes has not been studied adequately. To fill this gap, a computational study has been carried out to determine two key treatment parameters: the therapeutic temperature distribution and the extent of thermal damage. Prolate and oblate spheroidal tumors, of various aspect ratios, surrounded by a large healthy tissue region are assumed. Tissue temperatures are determined from the solution of Pennes’ bio-heat transfer equation. The mortality of the tissues is determined by the Arrhenius kinetic model. The computational model is successfully verified against a closed-form solution for a perfectly spherical tumor. The therapeutic temperature and the thermal damage in the tumor center decrease as the aspect ratio increases and it is insensitive to whether tumors of the same aspect ratio are oblate or prolate spheroids. The necrotic tumor area is affected by the tumor prolateness and oblateness. Good comparison is obtained of the present model with three sets of experimental measurements taken from the literature, for animal tumors exhibiting ellipsoid-like geometry. The computational model enables the determination of the therapeutic temperature and tissue thermal damage for magnetic hyperthermia of ellipsoidal tumors. It can be easily reproduced for various treatment scenarios and may be useful for an effective treatment planning of ellipsoidal tumor geometries.

Cryotherapy for liver metastases

BACKGROUND

The liver is affected by two of the most common groups of malignant tumours: primary liver tumours and liver metastases from colorectal carcinoma. Liver metastases are significantly more common than primary liver cancer and long-term survival rates reported for patients after radical surgical treatment is approximately 50%. However, R0 resection (resection for cure) is not feasible in the majority of patients. Cryotherapy is performed with the use of an image-guided cryoprobe which delivers liquid nitrogen or argon gas to the tumour tissue. The subsequent process of freezing is associated with formation of ice crystals, which directly damage exposed tissue, including cancer cells.

OBJECTIVES

To assess the beneficial and harmful effects of cryotherapy compared with no intervention, other ablation methods, or systemic treatments in people with liver metastases.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE Ovid, Embase Ovid, and six other databases up to June 2018.

SELECTION CRITERIA

Randomised clinical trials assessing beneficial and harmful effects of cryotherapy and its comparators for liver metastases, irrespective of the location of the primary tumour.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We extracted information on participant characteristics, interventions, study outcomes, and data on the outcomes important for our review, as well as information on the design and methodology of the trials. Two review authors independently assessed risk of bias in each study. One review author performed data extraction and a second review author checked entries.

MAIN RESULTS

We found no randomised clinical trials comparing cryotherapy versus no intervention or versus systemic treatments; however, we identified one randomised clinical trial comparing cryotherapy with conventional surgery. The trial was conducted in Ukraine. The trial included 123 participants with solitary, or multiple unilobar or bilobar liver metastases; 63 participants received cryotherapy and 60 received conventional surgery. There were 36 women and 87 men. The primary sites for the metastases were colon and rectum (66.6%), stomach (7.3%), breast (6.5%), skin (4.9%), ovaries (4.1%), uterus (3.3%), kidney (3.3%), intestines (1.6%), pancreas (1.6%), and unknown (0.8%). The trial was not reported sufficiently enough to assess the risk of bias of the randomisation process, allocation concealment, or presence of blinding. It was also not possible to assess incomplete outcome data and selective outcome reporting bias. The certainty of evidence was low because of risk of bias and imprecision.The participants were followed for up to 10 years (minimum five months). The trial reported that the mortality at 10 years was 81% (51/63) in the cryotherapy group and 92% (55/60) in the conventional surgery group. The calculated by us relative risk (RR) with 95% Confidence Interval (CI) was: RR 0.88, 95% CI 0.77 to 1.02. We judged the evidence as low-certainty evidence. Regarding adverse events and complications, separately and in total, our calculation showed no evidence of a difference in recurrence of the malignancy in the liver: 86% (54/63) of the participants in the cryotherapy group and 95% (57/60) of the participants in the conventional surgery group developed a new malignancy (RR 0.90, 95% CI 0.80 to 1.01; low-certainty evidence). The frequency of reported complications was similar between the cryotherapy group and the conventional surgery group, except for postoperative pain. Both insignificant and pronounced pain were reported to be more common in the cryotherapy group while intense pain was reported to be more common in the conventional surgery group. However, the authors did not report whether there was any evidence of a difference. There were no intervention-related mortality or bile leakages.We identified no evidence for health-related quality of life, cancer mortality, or time to progression of liver metastases. The study reported tumour response in terms of the carcinoembryonic antigen level in 69% of participants, and reported results in the form of a graph for 30% of participants. The carcinoembryonic antigen level was lower in the cryotherapy group, and decreased to normal values faster in comparison with the control group (P < 0.05).

FUNDING

the trial did not provide information on funding.

AUTHORS' CONCLUSIONS

The evidence for the effectiveness of cryotherapy versus conventional surgery in people with liver metastases is of low certainty. We are uncertain about our estimate and cannot determine whether cryotherapy compared with conventional surgery is beneficial or harmful. We found no evidence for the benefits or harms of cryotherapy compared with no intervention, or versus systemic treatments.

In vitro magnetic hyperthermia response of iron oxide MNP’s incorporated in DA3, MCF-7 and HeLa cancer cell lines

In the current work, iron oxide magnetic nanoparticles (MNP’s) were synthesized by thermal decomposition of Fe(acac)3-(iron acetylacetonate) compounds in high-boiling organic solvents containing stabilizing surfactants and examined as possible agents for magnetic hyperthermia treatment, according to their structural, magnetic and heating properties. Three different cancer cell lines (DA3, MCF-7 and HeLa cell lines) were used to assess the suitability of the MNP’s. The experimental results proved that the synthesized MNPs are non-toxic and the uptake efficiency was extremely good. Further, from in vitro hyperthermia results, very fast thermal response was observed (reaching hyperthermia levels in less than 200 s), which minimize the duration of the cell and human body exposure in a high frequency AC external magnetic field.

Tumor response to arterial embolization hyperthermia and direct injection hyperthermia in a rabbit liver tumor model

BACKGROUND AND OBJECTIVES

It is possible to arterially embolize or directly inject liver tumors in small animal models with ferromagnetic particles that generate hysteretic heating on exposure to an alternating magnetic field. The objective of this study was to compare the response of liver tumors to arterial embolization hyperthermia (AEH) and direct injection hyperthermia (DIH).

METHODS

Ten rabbits containing experimental hepatic tumors were treated with AEH, and a second group of ten rabbits were treated with DIH. The tumors of both groups were heated to 43 degrees to 50 degrees C for 20 minutes. Tumor response, which was determined by measuring change in tumor volume and by comparison of tumor mass after treatment with the mass of untreated control tumors of the same age, was assessed 14 days after treatment.

RESULTS

All tumors treated with AEH decreased in volume by 50% to 94% (P = 0.005), and their average mass (median 1.73 gm) was significantly less than that of untreated control tumors (median 8.01 gm, n = 20; P < 0.001). Three of the treated tumors were completely necrotic, while the remainder were at least 80% necrotic. Nine of the ten tumors treated with DIH increased in volume by at least 143% (P = 0.01), and their average mass (median 5.68 gm) was not significantly different from that of the untreated control tumors (P = 0.56).

CONCLUSION

These results indicate that AEH is more effective than DIH at moderately elevated temperatures. This is probably because the more widespread particle distribution that can be achieved using arterial embolization results in more extensive and complete treatment of the tumor.

Arterial embolization hyperthermia in porcine renal tissue

BACKGROUND

Arterial embolization hyperthermia (AEH) consists of arterially embolizing tumors with ferromagnetic particles that generate hysteretic heating on exposure to an alternating magnetic field. It was the objective of this study to evaluate AEH using the kidney of a large animal as a tumor model.

METHODS

Between 50 and 400 mg of ferromagnetic microspheres (32 microm in diameter) was arterially infused into the kidneys of three pigs. Temperature probes were inserted into renal tissue, skin, and subcutaneous fat. Each subject was then exposed to an alternating magnetic field for 5 min, while under a general anesthetic. A femoral artery catheter was used to monitor the cardiac pulse. Three days after treatment the renal tissue was chemically analyzed for iron content, which was then correlated with tissue heating rates.

RESULTS

There was a linear relationship between heating rate and iron concentration (N = 18, correlation = 0.72, P < 0.001) that suggested tissue iron concentrations in the range of 1.55 to 4.05 mg/g would yield tissue heating rates of 0.5 to 1.0 degrees C/min. No temperature increases were detected in control renal tissue (N = 6). The median increase in skin temperature after 5 min of heating was 0.8 degrees C (N = 6, min = 0.7 degrees C, max = 1.3 degrees C), and that in subcutaneous fat was 1.1 degrees C (N = 6, min = 0.8 degrees C, max = 1.2 degrees C). There was no detectable stimulation of cardiac or skeletal muscle or peripheral nerves during treatment. All subjects had uneventful 3-day posttreatment survivals.

CONCLUSION

This study has shown that AEH can target deep-seated, vascularized tissue in a large animal with therapeutic temperatures (> 42 degrees C), and that the treatment is safe and well tolerated. Further assessment of treatment schedules should allow for a human trial in the near future.

Effect of selective internal radiation therapy and hepatic arterial chemotherapy on normal liver volume and spleen volume

OBJECTIVE

To determine the effect of selective internal radiation therapy (SIRT) and hepatic arterial chemotherapy (HAC) on normal liver volume and spleen volume in patients receiving these treatments for advanced liver cancer.

METHODS

In a phase III clinical trial to assess the benefit of SIRT over HAC one group of patients received SIRT + HAC while a second group received HAC only. All patients in this trial who had abdominal CT scans available before treatment, and at 3, 6, and 12 months after treatment were evaluated. Changes in normal hepatic parenchyma (NHP) volume, portal vein diameter and spleen volume were calculated for each patient and analysed for significant trends.

RESULTS

The mean NHP volume decreased by 17% (P = 0.001) 12 months after treatment among patients receiving SIRT + HAC (N = 22), while the mean NHP volume among patients treated with HAC only (N = 15) was unchanged at 12 months. The mean portal vein diameter increased by 9% in both treatment groups, P = 0.048 and P < 0.001, respectively. The mean spleen volume increased by 48% (P < 0.001) and 26% (P = 0.001), respectively, in the two groups 12 months after treatment started. There was no clinical evidence of hepatic failure, portal hypertension or splenic dysfunction in any of the patients.

CONCLUSIONS

Treatment of patients with SIRT + HAC causes contraction of the normal hepatic parenchyma, while treatment with HAC alone has no significant effect. Treatment with either SIRT + HAC or HAC alone causes a significant increase in portal vein diameter and spleen volume by 12 months after treatment. The increase in spleen volume and portal vein size is likely to be due to portal hypertension resulting from scarring within the liver as a result of chemical and radiation hepatitis.

Targeting liver tumors with hyperthermia: ferromagnetic embolization in a rabbit liver tumor model

BACKGROUND AND OBJECTIVES

Ferromagnetic embolization hyperthermia (FEH) consists of arterially embolizing liver tumors with ferromagnetic particles, and then applying an external alternating magnetic field to generate hysteretic heating within the embolized particles. The objective of this study was to assess the ability of FEH to selectively target liver tumors with hyperthermia.

METHODS

Twenty rabbits containing hepatic VX2 carcinomas were arterially infused with ferromagnetic particles suspended in lipiodol, and then exposed to an external alternating magnetic field. Temperatures in the tumor, normal hepatic parenchyma (NHP), and rectum were recorded. Tumour and NHP were chemically analyzed for iron content, which was then correlated with the observed heating rates.

RESULTS

The mean tumor-to-NHP iron concentration ratio was 5.3:1 (P < 0.001, N = 20). The mean tumor heating rates were 3.0-11.5 times greater than those in the NHP (P < 0.001, N = 20). After 5 min of heating, the greatest increase in mean tumor temperature was 11.0 degrees C and the greatest increase in mean NHP temperature was 1.3 degrees C. There was a positive relationship between tumor iron concentration and heating rate (correlation coefficient = 0.82, P < 0.001, N = 20). A tumor iron concentration of 2-3 mg/g resulted in tumor heating rates of 0.5-1.0 degrees C/min.

CONCLUSIONS

Hepatic arterial infusion of lipiodol containing ferromagnetic particles can result in excellent targeting of liver tumors with hyperthermia on the subsequent application of an external alternating magnetic field. The promising results of this study warrant further investigation of FEH as a potential treatment for advanced liver cancer.

Status of hyperthermia in the treatment of advanced liver cancer

The vast majority of patients with malignant liver tumors have inoperable disease. These patients must rely on chemotherapy, radiotherapy, and various locoregional treatments. Although these treatments have demonstrated encouraging response rates, symptom palliation and occasional down staging of tumors, their impact on survival is minor. As a result there has been renewed interest in hyperthermia as a treatment option. This study reviews the current modalities of hyperthermia in terms of clinical results, side effects, limitations, and therapeutic standing.