Palliative treatment of hepatic tumours

FDG PET in preoperative assessment of colorectal liver metastases combining "evidence-based practice" and "technology assessment" methods to develop departmental imaging protocols: should FDG PET be routinely used in the preoperative assessment of patients with colorectal liver metastases?

In today's environment of progressively evolving and expensive imaging modalities, radiologists are asked to justify the use of resources to patients, referring physicians, hospital management, and third party payers. With this aim, the radiologist may use "top-down" or "bottom-up" "evidence-based practice" (EBP) techniques. "Top-down" suggests that the practitioner should wait until a higher authority, external to their practice, generates a solution to practice dilemmas (e.g., National Institute for Health and Clinical Excellence [NICE] guidelines). "Bottom-up" however, is based on the theory that the ordinary practitioner is best served by a decentralized approach to problem solving that is internal to their practice. The technology assessment framework modeled by Mackenzie and Dixon comprehensively assesses the effects of imaging using levels of efficacy including diagnostic performance, diagnostic impact, and therapeutic impact, impact on health and cost effectiveness. In this article, we describe how issues regarding new imaging modalities in ordinary radiology practice can be addressed by using stepwise "bottom-up" EBP techniques combined with the technology assessment framework. We also detail how EBP techniques form an integral part of practice-based learning among radiology residents as part of noninterpretive residency training. The following clinical scenario is used: your hospital's chief hepatobiliary surgeon writes to your department regarding the lack of access to 18-fluoro-2-deoxy-D-glucose positron emission tomography in the preoperative assessment of patients with colorectal cancer liver metastases under consideration for hepatic resection. How would you approach this problem? Here is how we would do it.

Role of FDG-PET in surgical management of patients with colorectal liver metastases

BACKGROUND

[(18)F]-fluorodeoxyglucose positron emission tomography (FDG-PET) is reported to change the management in 20-56% of patients with recurrent or metastatic colorectal cancer. It is not clear if FDG-PET has a role in all such patients or only a subgroup. The aim of the present study was to assess the influence of FDG-PET on the surgical management of patients with known or suspected colorectal liver metastases.

METHODS

Patients undergoing FDG-PET for investigation of known or suspected colorectal liver metastases were identified from a South Australian database. Case notes were reviewed retrospectively to determine the influence of FDG-PET findings on patient management. Findings from FDG-PET scanning were compared with findings from conventional diagnostic investigations and operative findings.

RESULTS

Overall, in four of 16 patients (25%) management was influenced by FDG-PET findings. FDG-PET altered management in four of eight (50%) patients with non-diagnostic liver lesions on computed tomography (CT) or with elevated carcinoembryonic antigen levels but no liver lesion on CT. In all eight patients with CT diagnosed resectable liver metastases, the addition of FDG-PET did not influence the management.

CONCLUSIONS

The findings support the use of FDG-PET in the assessment of selected patients with suspected colorectal liver metastases and equivocal findings on conventional diagnostic investigation.

Electrolysis and other local ablative treatments for non-resectable colorectal liver metastases

The present paper is a review of the current ablative treatment options for the treatment of colorectal liver metastases. Cryotherapy, microwave coagulation therapy, radiofrequency ablation and laser-induced thermotherapy are discussed. Electrolysis, a novel non-thermal ablative treatment, is described. Potential benefits of electrolysis include the apparent ability to safely and effectively treat lesions abutting major hepatic structures and the lack of a systemic inflammatory reaction following electrolytic ablation. Further studies in animals and humans are needed to confirm this potential and to further refine the methods of electrolytic treatment of colorectal liver metastases.

Microwave coagulation therapy for multiple hepatic metastases from colorectal carcinoma

BACKGROUND

Compared with other treatments, microwave coagulation is a relatively less invasive treatment for various kinds of solid tumors. Although its effectiveness in primary hepatocellular carcinoma has been shown, its effectiveness in the treatment of hepatic metastases from colorectal carcinoma has been unclear. The aim of this study was to evaluate its effectiveness in the treatment of multiple hepatic metastases from colorectal carcinoma by comparing this technique with that of hepatic resection.

METHODS

Thirty patients with multiple metastatic colorectal tumors in the liver who were potentially amenable to hepatic resection were randomly assigned to treatment with microwave coagulation (14 patients) or hepatectomy (16 patients). Tumors in the microwave group were coagulated after laparotomy at an output of 60-100 W for 2-20 minutes under the guide of ultrasonography, whereas tumors in the hepatectomy group were treated with lobectomy, segmentectomy, subsegmentectomy, and/or wedge resection.

RESULTS

One-, 2-, and 3-year survival rates and mean survival times were 71%, 57%, 14%, and 27 months, respectively, in the microwave group, whereas they were 69%, 56%, 23%, and 25 months, respectively, in the hepatectomy group. The difference between these two groups was statistically not significant (P = 0.83). On the other hand, the amount of intraoperative blood loss in the microwave group (360 +/- 230 mL) was smaller than that in the hepatectomy group (910 +/- 490 mL, P < 0.05). Blood transfusion was necessary for 6 patients in the hepatectomy group, but it was not necessary in the microwave group.

CONCLUSIONS

Microwave coagulation therapy is suggested to be equally effective as hepatic resection in the treatment of multiple (two to nine) hepatic metastases from colorectal carcinoma, whereas its surgical invasiveness is less than that of hepatic resection.

Local treatment of hepatic metastases with low-level direct electric current: experimental results

BACKGROUND

Several authors have recently reported encouraging results from low-level direct current therapy in easily accessible malignant tumors. However, antitumoral effects in colorectal metastases have not been investigated experimentally.

METHODS

Using an animal model with induced hepatic metastases, we analyzed the effectiveness and the tumor growth dynamics after direct current application. Three weeks after induction tumor volumes were estimated with magnetic resonance imaging (MRI). Then direct current (80 C/cm3) was applied in the treatment group by means of one anode in the tumor center and four cathodes peripherally. In the control group electrodes were placed without applying current. Tumor growth dynamics was analyzed with MRI after 3 and 5 weeks. After this all animals were killed, and the livers histologically examined.

RESULTS

After 5 weeks MRI showed a 1.6-fold tumor enlargement in the treatment group versus a 2.9-fold enlargement in the control group (Student t test, P=0.0051). The histopathologic analysis of the treated livers yielded a 21% complete response rate and a 78% partial response rate. No necroses were found in the control group.

CONCLUSIONS

These results confirm the effectiveness of low-level direct current application as a potential modality for the treatment of hepatic metastases.

Superselective intra-arterial chemotherapy with mitomycin C for hepatocellular carcinoma

Thirty-six patients with primary hepatocellular carcinoma were treated by superselective intra-arterial chemotherapy with mitomycin C (SIAC) between 1981 and 1990, either as primary chemotherapy without operation (28) or as additional therapy after resective surgery (8). During the same period 10 patients were resected radically and 26 patients treated conservatively. The overall response rate to SIAC was 25% (9/36), comprising two complete and seven partial responses. The cumulative 5-year survival rate was significantly related to the percentage of hepatic replacement (PHR) (P < 0.01) and to resective surgery (P < 0.01). Overall 5-year survival was only 4% and all the patients with PHR over 75% died within 2 or 3 years. Cessation of chemotherapy was necessary in 72% of cases (26/36), because of tumour progression in 20 cases, chemotherapy toxicity in four and one technical error in one and patient refusal in one. The results of the use of SIAC as a chemotherapeutic agent for hepatocellular cancer may be regarded as disappointing, as the response rate remained low and the medication was unable to prevent tumour progression in most cases. We intend to use SIAC only for stage I-II tumours and as additional therapy after surgery when the radicality remains uncertain.

Interstitial laser hyperthermia: a new approach for treating liver metastases

The palliative management of hepatic metastases remains unsatisfactory. There is a need for a simple non invasive technique which can stop or retard the rate of tumour growth. In principle, Interstitial Laser hyperthermia may fulfil such a role. In experimental studies, this technique produced precise in situ necrosis within solid organs which healed safely. In a pilot feasibility study, we treated ten patients with a total of 18 hepatic metastases on 31 occasions using a percutaneous approach to achieve an overall objective response rate of 44%. The treatment proved simple to perform, was well tolerated and produced radiological evidence of necrosis in small metastases (diameter less than or equal to 3 cm). However, further research is required before the technique can be regarded as established. Its future role in most cases will be to control the growth of discrete hepatic metastases unsuitable for resection. In instances where the extent of necrosis can be matched accurately to tumour volume, the potential for cure exists.

Role of interstitial therapy in the treatment of liver cancer

Conventional palliative management of inoperable focal hepatic tumours remains unsatisfactory. Interstitial techniques such as cryotherapy, alcohol injection, low power laser hyperthermia and interstitial radiotherapy offer alternative approaches. Cryotherapy is an effective and precise technique for inducing tumour necrosis. It can only be performed at laparotomy making it relatively invasive and retreatment impractical. Alcohol is cheap and can be injected percutaneously. However, inhomogeneous distribution produces imprecise and nonreproducible lesions. Low power laser hyperthermia produces precise and reproducible areas of necrosis that are roughly spherical in shape. At present, this technique is most effective for small tumours. Interstitial radiotherapy remains the least evaluated of all the interstitial techniques. Unlike cryotherapy and low power laser hyperthermia, the biological effect of ethanol injection and interstitial radiotherapy cannot be monitored in real time by ultrasound. With the exception of cryotherapy, all methods can be applied percutaneously with low morbidity and mortality. None of these techniques is established, but they may offer the prospect of cure in cases where all areas of tumour can be positively identified and fully treated. However, in most instances the intention is to control the growth of relatively small discrete volumes of tumour within the hepatic parenchyma.

Intermittent hepatic arterial or portal occlusion reduces liver tumor growth

The effect of repeated, intermittent hepatic vascular occlusion on liver tumor growth was studied in 32 rats. An adenocarcinoma was inoculated in the left liver lobe. After 8 days, the tumor size was measured and then, in three groups, the hepatic artery was occluded intermittently during 5 days for 15 min, 1 hr, or 2 hr daily, respectively. The tumor growth after 6 days in these groups was compared with that in a group where instead the portal vein was occluded intermittently during 5 days for 15 min, and with that in a group of sham-operated control rats. In the control rats, the tumor volume (mean +/- SEM) increased from 0.16 +/- 0.03 to 1.34 +/- 0.15 cm3 during the 6 days of experiment. It was found that repeated, intermittent occlusion of the hepatic artery or the portal vein, retarded the liver tumor growth to 30-60% of the growth rate in sham-operated controls (P less than or equal to 0.015). The 15-min daily hepatic artery or portal vein occlusion was found to reduce the tumor growth rate as much as daily hepatic artery occlusion for 2 hr. It is suggested that short, daily, intermittent hepatic vascular occlusions might be efficient in the palliative treatment of liver malignancy.