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Selective Radionuclide Localisation in Primary Liver Tumours

The therapeutic potential of 131I-Lipiodol was investigated in 8 patients with cholangiocarcinoma (CCA) and 15 patients with hepatocellullar carcinoma (HCC). Patients received one or two doses of 131I-Lipiodol via hepatic arterial injection. The mean total administered activity was 668 (SD 325) MBq in CCA and 953 (SD 477) MBq in HCC. One patient with CCA retained 131I-Lipiodol. The cumulative radiation dose was 9.6 Gy to tumour, 6.4 Gy to liver and 1.5 Gy to lung. The patient remained asymptomatic with no evidence of tumour 30 months from the start of treatment, whereas the remaining 7 patients exhibited tumour progression. The mean survival in CCA was 11.6 (SD 14.5) months. All 15 patients with HCC retained 131I with tumour: liver ratios of up to 30:1. The mean cumulative radiation dose was 34.7 (SD 32.4) Gy to tumour, 3.3 (SD 1.5) Gy to liver and 4.4 (SD 2.3) Gy to lung. The mean dose per administered activity was 3.8 (SD 4.1) cGy/MBq. Partial response (reduction in tumour size > 50%) was observed in 6 patients (40%). The mean survival was 7.1 (SD 6.0) months. 131I-Lipiodol can deliver highly selective internal irradiation to foci of HCC with evidence of objective response and may be the treatment of choice for patients with cirrhosis and a small tumour.


INTRODUCTION
Lipiodol (Lipiodol Ultra Fluid, May & Baker, England) is a lipid derived from poppyseed oil. It contains 475mg of iodine per ml (38% by weight) and has been used for many years as a contrast medium, principally in lymphography. In 1979 Nakakuma et al. injected Lipiodol into the hepatic artery and demonstrated its selective retention in loci of hepatocellular carcinoma1. Using a simple exchange reaction2, part of the iodine component of Lipiodol may be replaced by the radioactive isotope 131I, making it an ideal vehicle for the delivery of internal 131 radiotherapy, I-Lipiodol has been studied using scintigraphy in human subjects and exhibits a similar pattern of uptake and retention to the non-radioactive lipid3-6. Tsai et al. have measured the uptake of 131I-Lipiodol in an animal tumour model and have shown it to have a significantly longer effective half life in tumour than in normal tissue, resulting in almost complete necrosis of the tumour7. Toxicity to thyroid, bone marrow or lung has not been reported. This paper is based on a presentation to the 4th World Congress of HPB Surgery in Hong Kong, June 1992. 185 Previous authors have reported promising results using 131I-Lipiodol in hepatocellular carcinoma (HCC), with tumour shrinkage and symptomatic improvement in the majority of patients5' 8. Response has been reported to be greatest in small loci of HCC without significant vascular shunting9. In a prospective analysis of fifty patients with Stage I and II HCC by Le Jeune et al. the overall survival at 6 months, 12 months and 2 years was 60%, 31% and 23% respectively1. Initial studies have shown 1311 retention in small colorectal metastases, but localisation in larger deposits is very pooru.
Our earlier studies on Lipiodol-targeted chemotherapy 12 showed no evidence of response in the tumours studied, although survival in Stage I and II HCC was better than expected. They did, however, demonstrate excellent deposition and retention of Lipiodol in HCC, particularly smaller tumour loci. The aim of this study was to investigate the therapeutic potential of 13q-Lipiodol in two histological variants of primary liver cancer. Lipiodol using two sterile 20ml glass syringes and a 3-way tap with luer locks. This volume of Lipiodol was administered by slow injection into the hepatic artery and the system flushed with 20ml of normal saline. Firm pressure was applied to the groin puncture site for 5 mins using a sterile lead-gloved hand. All procedures were designed to keep radiation exposures to staff as low as reasonably achievable. Catheterisations were performed at the end of a session in the Angiography suite to allow time for decontamination should any spillage occur, and only essential staff were present in the room during the procedure. Glass syringes were employed throughout as Lipiodol has a solvent action on polystyrene. Monitoring of both room and staff was carried out immediately following completion of the procedure.

PATIENTS, MATERIALS AND METHODS
Routine clinical observations were carried out following angiography. Daily haematological and liver indices were performed for the duration of the inpatient stay. The treatment was repeated in patients who showed continued clinical wellbeing and/or reduction in tumour size. The median administered activity was 600 MGq (range 300-1160 MBq) in CCA and 875 MBq (range 525-2055 MBq) in HCC.

Tumour Assessment
All patients underwent 99Tc colloid liver scintigraphy prior to treatment for comparison with later 1311 scintigraphy. To assess Lipiodol uptake and response to treatment, a CT scan of the liver was performed at 10 days. Perpendicular diameters were measured for each tumour focus. Tumour volumes were calculated from the CT scan using the formula: Volume maximum tumour diameter x perpendicular diameter 2 Tumour response was assessed on lesion size (determined on serial CT measurements) and tumour marker levels. Patients were graded Complete Response (CR), Partial Response (PR), No Change (NC) or Progressive Disease (PD) according to WHO criteria14. Toxicity grading was also assessed on WHO criteria14. AFP levels were measured at diagnosis and during treatment; they were within normal limits in all patients with CCA.
Liver retention of the labelled lipid was assessed by scintigraphy at 24-48 hours and 6-8 days using a Scintronix 480S Digicamera fitted with a high energy 1.9mm hexagonal-holed plane collimator. Planar anterior and posterior images of the liver and thorax were acquired over a five minute period and stored on floppy disk for later analysis. The pattern of uptake was compared to the distribution of Lipiodol within tumour tissue on synchronous CT scans of the liver and to 99Tc uptake on the pre-treatment colloid scan. Using the acquired images, regions of interest were drawn around the tumour, liver and lungs, and the total counts recorded for each region. Counts were also recorded over an equivalent area of low activity distant from the liver, and this "background" count subtracted from the tissue count in each case.
Three patients with HCC were scanned on an IGE Gemini 700 camera fitted with a 400KeV parallel-hole high resolution collimator, linked to a Saturn nuclear medicine computer for data acquisition and image processing. IGE software was used for tomographic image reconstruction and dosimetry. The doses of radioactivity administered to the tumour, surrounding liver and lung were calculated using a standard formulaeTM.

Localisation
Although prolonged retention of activity was observed in the peripheral liver parenchyma in patients with hilar tumours, a comparison of the scintigraphic and tomographic appearances 6-10 days after treatment showed no evidence of tumour-selective retention of the radio-isotope in any patient. However, diffuse retention was observed in one patient (Patient No. 07) who was reassessed 7 weeks following treatment and found to retain focal activity in the hilar mass ( Figure 1). She has received a further course of 131I-Lipiodol and remains alive and well 30 months from the start of treatment. The cumulative radiation dose from two treatments was calculated to be 9.6 Gy to tumour, 6.4 Gy to liver and 1.5 Gy to lung.

Outcome
The clinical details and results of treatment in CCA are summarised in Table 1 The longest surviving patient has also shown evidence of disease progression clinically and has required readmission for recurrent obstructive jaundice, treated by segment III hepatico-jejunostomy. Although good localisation of the isotope was observed even in large, multifocal deposits the highest tumour: liver ratios were seen in patients with small discrete tumours. In one case tumour 1311 uptake was not confined to the liver. The patient (No. 19), a 41 year old man with a massive central hepatoma, received a small initial dose of isotope due to concern over poor liver function. Gamma imaging showed localisation within the liver but also demonstrated a small mediastinal nodule (Figure 2a). Five months later he remained well with no change in size of the tumour on CT scan and a second larger dose was administered. On this occasion the 131I-Lipiodol was seen to localise in the thorax following intrahepatic injection (Figure 2b). Imaging at 48 hours confirmed activity within the heart (Figure 2c). Echocardiography subsequently confirmed a large tongue of turnout extending from the hepatic veins to the right atrium.
The mean cumulative radiation dose was 34.7 (SD 32.4) Gy to tumour, 3.3 (SD 1.5) Gy to liver and 4.4 (SD 2.3) Gy to lung. The mean dose per administered activity was 3.8 (SD 4.1) cGy/MBq (Table 2). Outcome Partial tumour response (PR) was seen in 6 patients (Table 3), with reduction in tumour size > 50% in all 6 and reduction in serum AFP levels in two. No change (NC) was observed in 4 patients and 4 patients had progressive disease (PD).
Patients exhibiting PD received a significantly lower mean tumour radiation dose than patients with PR or NC (Figure 3, p 0.04, pooled estimate of variance). 17 As we have previously reported histological proof of response was obtained in one patient (No. 10) with recurrent HCC. Good tumour localisation was observed following 131I-Lipiodol administration (Figure 4a,b) and 3 months later a 5 cm wedge of liver containing 2 discrete tumour nodules was resected. Histological examination of the resected specimen showed both tumour nodules to be completely necrotic and surrounded by a zone of fibrotic but non-malignant parenchyma ( Figure 4c). Five patients were alive and under regular follow-up at the end of the trial, having survived 4-19 months from the start of treatment. Eight patients died, two from widespread extrahepatic metastases and two from hepatic failure. Four patients died from tumour progression: all had extensive multifocal disease which had failed to respond to previous chemotherapy. Two patients were lost to followup, one of whom was in remission at 16 months. Survival in HCC, calculated by life-table analysis, was 61% at 6 months and 31% at 1 year ( Figure 5). The median (a) (b) (c) Figure 2 Intracardiac localisation of 131I. (a) Activity in mediastinal nodule (AP gamma scan at 48 hours) (b) Supra-diaphragmatic focus of activity (Oblique lateral CXR at 1 hour) (c) Activity in heart (AP gamma scan at 48 hours).

Adverse Effects
There were no complications associated with percutaneous catheterisation. No significant activity was recorded in thyroid or bone marrow on whole body gamma scintigraphy, and no patient developed thyroid insufficiency or haematological evidence of marrow depression. In patients with small, discrete deposits of HCC activity in the lung fields remained low following intrahepatic injection but in patients with massive or multifocal tumours hepatopulmonary shunting of the isotope was observed. The mean radiation dose to the lungs was less than 5 Gy and no clinical signs of acute pneumonitis or chronic pulmonary fibrosis were observed in any patient. Mild to moderate pyrexia (Grade 1-2) was seen following 13 treatments (45%). Mild to moderate elevation of liver transaminases and bilirubin (Grade 1-2) occurred following 10 treatments (35%). Significant hepatotoxicity occurred in one patient (No. 11), a 75 year old cirrhotic (Child-Pugh Grade B) who developed hepatic encephalopathy and oliguria 2 days following a second treatment x31 with I Lipiodol. The dose of radioactivity to tumour and non-neoplastic liver was calculated to be 34.5 Gy and 3.7 Gy respectively. Liver ultrasound demonstrated liquefaction of the tumour mass, and his deterioration in liver function was ascribed to massive tumour necrosis. He was resuscitated and showed a slow but progressive improvement in hepatorenal function. A further decline in his condition was associated with episodes of sepsis, and he died one month following the treatment.  14 DISCUSSION Results in CCA were disappointing, with only one of eight patients demonstrating limited retention of activity in the region of the biliary obstruction on gamma scintigraphy. Despite a relatively small radiation dose of approximately 1000 cGy this patient survived for 30 months with no evidence of progression of her disease. She required two hospital admissions for stent replacement during the follow-up period but is currently asymptomatic with no indwelling stents and no evidence of residual disease on CT scan.
To date there has been only one report on the use of 131I-Lipiodol in a case of intrahepatic cholangiocarcinomalS: no selective retention of the radio-isotope occurred. Targeted chemotherapy using an emulsion of Lipiodol with doxorubicin, in combination with stenting and long term systemic chemotherapy using mitozantrone, has been described in one case of cholangiocarcinoma19. The patient was reported to be alive and well 27 months following diagnosis. Our own experience in three cases treated with a Lipiodol-epirubicin emulsion has been disappointing, with a mean survival of 5.4 months from the start of treatment12. Systemic chemotherapy is rarely of benefit in cholangiocarcinoma, and whole liver irradiation is dose-limited to a maximum of 3500 rads by the low tolerance of normal liver tissue. However, the use of these modalities in combination with 131I Anti-CEA has been reported to increase both response rates and survival2. It is possible that a similar radical multimodal approach incorporating Lipiodol-targeted radiotherapy may provide an effective means of palliation in some patients with cholangiocarcinoma.
All fifteen patients with HCC showed tumour-specific retention of activity with tumour: liver dose ratios of up to 30:1. Previous investigators have found 131I-Lipiodol to be retained almost exclusively by the liver and lungs3. A measure of the accuracy of the dosimetry calculations used in this study can therefore be obtained from comparison of tissue activities with the administered activity, derived from the measured activity of the 31I-Lipiodol aliquot prior to injection minus the residual activity the end of the procedure. Calculation of the combined activities in tumour, liver and lung at time t 0 gave a median value of 87% of the estimated administered activity, with a range of 70 118%. Taking into account losses to other organs via the splanchnic circulation, and overestimation of the administered activity due to adherence of activity to the syringe and catheter, this is an acceptable accuracy for planar dosimetry. However, the accuracy of dosimetry based on planar scintigraphy is inferior to that achievable using the more sophisticated technique of SPECT imaging. For the last three cases in this series we had access to a tomographic gamma camera, which acquires 60 images at intervals of 5 degrees rotation with an exposure time of 5 seconds 1 minute. By constructing a tomographic gamma image this effectively eliminates errors from "background" activity in surrounding tissues.
Partial tumour response was seen in two of three patients with Stage I tumours (67%) and four of eleven patients with Stage II tumours (36%). There was no significant difference in response rates between Stage I and II tumours (p 0.76, Fisher exact probability test).
Patients showing response included one patient with fibrolamellar HCC. The patient (No. 16), a 42 year old woman, presented with a massive tumour of the right hepatic lobe invading the diaphragm, which had failed to respond to intra- 131I-Lipiodol therapy the tumour regressed to 20% of its original volume (Figure 6), and the patient remains asymptomatic 19 months later. Spence et al. 2 have reported long term survival in a similar case treated by Lipiodol-targeted chemotherapy; Lipiodol-targeted radiotherapy may also be effective in fibrolamellar HCC.
The mean survival in HCC was 7.1 (SD 6.0) months. Survival in Stage I was better than in Stage II, although the number of patients with Stage I disease was very small. The mean survival of patients showing partial response (11.6 months, SD 6.8) was significantly better than that of patients with tumour progression or no change (3.8 months, SD 1.7;p 0.004, pooled estimate of variance). This accords with previous work on 131I brachytherapy: Order et a/.22, in an analysis ot the results of targeted 131I antibody therapy in 343 patients, have demonstrated improved survival in those patients whose tumours decreased in volume by more than 30% on serial CT scanning. The cumulative survival rates of 61% at 6 months and 31% Multiple treatments might be administered more easily via an infusion pump than by repeated percutaneous cannulation as employed in this series. However, external pumps are cumbersome and frequently complicated by thrombosis and sepsis, whereas implantable systems are more convenient but are associated with a significant local complication rate. Sclerosing cholangitis, chemical hepatitis, gastritis and cholecystitis have all been reported25. The only treatment-related death in this series resulted from sepsis and hepatorenal failure. The mean radiation dose to the hepatic parenchyma for all cases was less than 4 Gy, and no evidence ot hepatotoxicity was detected in the remaining patients. However, as a result of this lethal complication we have modified our protocol and now give a smaller amount of isotope in cirrhotic patients undergoing repeat treatments.
In summary, the results of 13-Lipiodol localisation in CCA were disappointing, with evidence of tumour targeting in only one patient. However, the low toxicity of 131I-Lipiodol might justify its use as part of a regime combining several treatment modalities. In HCC 131I-Lipiodol therapy has advantages over current non-surgical therapies in terms of cytotoxic potential and low toxicity, resulting in objective response in 40% ot patients. A good result was also observed in one patient with fibrolamellar HCC. 3I-Lipiodol proved useful in patients with tumour recurrence following surgery" it may also have a possible role in treating intrahepatic recurrences following orthotopic liver transplant. Caution is advocated in patients with poor hepatic or renal function, particularly if treatments are repeated. We believe that there is a need tor a larger randomised controlled study of this modality in patients with Stage I and II HCC.

INVITED COMMENTARY
Following Nakakuma and his colleagues surgical observations on the selective retention of liver tumours1, there has been increasing interest in utilising this "vehicle" for the delivery of both cytotoxic chemotherapy and radiotherapy. Initial results have been promising in terms of tumour shrinkage and symptomatic improvement but consistent survival data is lacking. This paper reports the preliminary results of a small pilot study of 131-I lipiodol in both cholangiocarcinoma and hepatocellular carcinoma.
There are several aspects which deserve comment. The method of delivery employed is by percutaneous catheterisation of the femoral artery. Other groups, including our own2, have preferred operative placement of the catheter with a subcutaneous "port". This has the advantage of allowing repeated daily injections so enabling fractionated doses to be given at repeated intervals. In addition it reduces the rate of contamination and spillage of radioactive material. For example if spillage occurred in the X-ray department this would inevitably mean closure of a screening room for several weeks! In addition the risks of radioactive exposure to staff using this technique is greater than with a closed system. With regard to tumour assessment the ratios of tumour: liver depends very much upon whether the liver region-of-interest was the liver or just a section of normal liver. If it was the former then to dose ratios of tumour: liver seem very high when judged by visual inspection of lipiodol images provided.
The lack of tumour-selective retention in cholangiocarcinoma is disappointing especially in view of the favourable uptake in hepatocellular carcinoma. The major effects however appear to be determined by the size of tumours. Multifocal small deposits being the most avid retainers of radioactivity. It should be noted that this is also a feature of liver metastases2. Clearly both pathological size and histology will need to be taken into account in determining selection of suitable patients.
The authors have paid particular attention to adverse effects which is a major consideration in phase I-II studies of this type. In general these are mild but hepatotoxicity is a theoretical possibility and accurate placement of the catheter is essential if gastritis and cholecystitis are to be avoided.
Overall this paper represents a valuable, albeit preliminary, evaluation of lipiodol localisation in primary liver tumours and suggests that further work on this novel treatment is justified.

Irving Taylor
Professor of Surgery and Head of Department University College London