Escalated focal liver radiation and concurrent hepatic artery fluorodeoxyuridine for unresectable intrahepatic malignancies

Feasibility and efficacy of high-dose three-dimensional-conformal radiotherapy in cirrhotic patients with small-size hepatocellular carcinoma non-eligible for curative therapies--mature results of the French Phase II RTF-1 trial

PURPOSE

Hepatocellular carcinoma (HCC) is a poor prognosis tumor, and only 20% of patients will benefit from curative therapies (surgery, liver transplantation, percutaneous ablation). Although conventional radiotherapy has been traditionally regarded as inefficient and toxic for cirrhotic patients, three-dimensional conformal radiotherapy (3DCRT) has provided promising preliminary data for the treatment of HCC.

METHODS AND MATERIALS

Prospective phase II trial including Child-Pugh A/B cirrhotic patients with small-size HCC (1 nodule < or =5 cm, or 2 nodules < or =3 cm) nonsuitable for curative treatments, to assess tolerance and efficacy of high-dose (66 Gy, 2 Gy/fraction) 3DCRT.

RESULTS

Twenty-seven patients were enrolled. Among the 25 assessable patients, tumor response was observed for 23 patients (92%), with complete response for 20 patients (80%), and partial response for 3 patients (12%). Stable disease was observed in 2 patients (8%). Grade 4 toxicities occurred in 2 of 11 (22%) Child-Pugh B patients only. Child-Pugh A patients tolerated treatment well, and 3/16 (19%) developed asymptomatic Grade 3 toxicities.

CONCLUSION

High-dose 3DCRT is a noninvasive, well-tolerated modality that is highly suitable for the treatment of small HCCs in cirrhotic patients, with promising results. However, additional trials are needed to optimize this technique and formally compare it with the usual curative approaches.

Radiation-induced hepatic toxicity after radiotherapy combined with chemotherapy for hepatocellular carcinoma

AIM

The purpose of the present study was to analyze hepatic toxicity following radiotherapy combined with regional chemotherapy for hepatocellular carcinoma (HCC).

METHODS

From 2001 to 2003, a total of 132 patients with HCC received 3-D conformal radiation therapy (3D-CRT) combined with chemotherapy. Patients were divided into two groups based on drug localization: the transcatheter arterial chemoembolization (TACE) group, where the chemotherapeutic drug (adriamycin) was localized within the tumor, and the non-TACE group, where the drugs (adriamycin, cisplatin, 5-fluorouracil) were diffusely spread over the entire liver.

RESULTS

Patients were evaluated by biochemical parameters for any hepatic toxicity prior to, during, and until 12 months after 3D-CRT. Hepatic toxicity was defined as radiation-induced liver disease (RILD) or combined modality-induced liver disease (CMILD), which is defined as RILD with abnormal elevation of total bilirubin levels. In the TACE group, three patients developed RILD (5.6%) and none developed CMILD. In the non-TACE group, three patients (3.7%) and seven patients (8.8%) developed RILD and CMILD, respectively.

CONCLUSION

Hepatic toxicity following radiotherapy combined with regional chemotherapy for HCC might be influenced by the distribution of the chemotherapeutic drugs. A more precise understanding of hepatic toxicity from chemoradiotherapy will help design optimal treatments for HCC.

Defining internal target volume (ITV) for hepatocellular carcinoma using four-dimensional CT

BACKGROUND AND PURPOSE

To define individualized internal target volume (ITV) for hepatocellular carcinoma using four-dimensional computed tomography (4DCT).

MATERIALS AND METHODS

Gross tumor volumes (GTVs) and clinical target volumes (CTVs) were contoured on all 10 respiratory phases of 4DCT scans in 10 patients with hepatocellular carcinoma. The 3D and 4D treatment plans were performed for each patient using two different planning target volumes (PTVs): (1) PTV(3D) was derived from a single CTV plus conventional margins; (2) PTV(4D) was derived from ITV(4D), which encompassed all 10 CTVs plus setup margins (SMs). The volumes of PTVs and dose distribution were compared between the two plans.

RESULTS

The average PTV volume of the 4D plans (328.4+/-152.2cm(3)) was less than 3D plans (407.0+/-165.6cm(3)). The 4D plans spared more surrounding normal tissues than 3D plans, especially normal liver. Compared with 3D plans, the mean dose to normal liver (MDTNL) decreased from 22.7 to 20.3Gy. Without increasing the normal tissue complication probability (NTCP), the 4D plans allowed for increasing the calculated dose from 50.4+/-1.3 to 54.2+/-2.6Gy, an average increase of 7.5% (range 4.0-16.0%).

CONCLUSIONS

The conventional 3D plans can result in geometric miss and include excess normal tissues. The 4DCT-based plans can reduce the target volumes to spare more normal tissues and allow dose escalation compared with 3D plans.

Analysis of organ motion effects on the effective fluences for liver IMRT

An effective fluence concept was employed to make forward dose calculations to investigate the effects of a distorted fluence map on dose plans. Fluence changes caused by organ motion were calculated using Chui's algorithm (2003 Med. Phys. 30 1736). In two test cases with various fluence maps, the effects of motion were simulated using a maximal displacement from 5 mm to 25 mm; 108 fluence maps that were calculated from 16 IMRT plans for eight liver cancer patients were analyzed and compared with and without gating. Fluoroscopic measurements were made of a moving diaphragm in this study. Fluence changes associated with superior-inferior organ motion, perpendicular to the moving MLC, were also examined. The effects of motion on the fluence maps were evaluated from both the fluence differences between static and motion and the chi function. The maximum displacements of the organs in all of these cases were analyzed and correlated with the change in fluence generated from the liver IMRT plans. The dosimetric effects on the target coverage were evaluated for each plan. The results indicate that, for the same fluence map, the mean fluence intensity error or the percentage of the fluence points that have an unacceptable error is linearly related to the extent of motion. For different fluence maps, the degree to which the fluence is distorted by motion is strongly related to the product of the motion extent and the fluence gradient in the direction of diaphragm motion. For eight liver patients and 16 IMRT plans in this work (with gated technique, motion extent from 0.5 cm to 1.0 cm; without gated technique, motion extent from 0.9 cm to 1.8 cm), the fluence modulations are mild, such that the respiratory motion of each patient did not strongly affect the CTV coverage. The mean dose error is 1.5% for free motion (0.9-1.8 cm) and is around 1% for gated motion (0.5-1 cm).

Hepatitis B virus reactivation after three-dimensional conformal radiotherapy in patients with hepatitis B virus-related hepatocellular carcinoma

PURPOSE

To investigate whether three-dimensional conformal radiotherapy (3D-CRT) influences hepatitis B virus (HBV) reactivation and chronic hepatitis B (CHB) exacerbation in patients with HBV-related hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

Of the 48 HCC patients with HBV who underwent 3D-CRT to the liver, 16 underwent lamivudine therapy before and during 3D-CRT (Group 1) and 32 did not receive antiviral therapy before 3D-CRT (Group 2). To analyze spontaneous HBV reactivation, we included a control group of 43 HCC patients who did not receive any specific treatment for HCC or CHB.

RESULTS

The cumulative rate of radiation-induced liver disease for Groups 1 and 2 was 12.5% (2 of 16) and 21.8% (7 of 32), respectively (p > 0.05). The cumulative rate of HBV reactivation was significantly greater in Group 2 (21.8%, 7 of 32) than in Group 1 (0%, 0/16) or the control group (2.3%, 1 of 43; p < 0.05 each). The cumulative rate of CHB exacerbation, however, did not differ significantly between Groups 2 (12.5%, 4 of 32) and 1 (0%, 0 of 16) or the control group (2.3%, 1 of 43; p > 0.05 each). The CHB exacerbations in the 4 Group 2 patients had radiation-induced liver disease features but were differentiated by serum HBV DNA changes. Two of these patients required antiviral therapy and effectively recovered with lamivudine therapy.

CONCLUSIONS

In patients with HBV-related HCC undergoing 3D-CRT, HBV reactivation and consequent CHB exacerbation should be considered in the differential diagnosis of radiation-induced liver disease, and antiviral therapy might be considered for the prevention of liver function deterioration after RT.

Radiation-induced hepatitis B virus reactivation in liver mediated by the bystander effect from irradiated endothelial cells

PURPOSE

Hepatitis B virus (HBV) reactivation is one unique pathogenesis in Asian carriers with liver toxicity after radiotherapy for hepatobiliary malignancies. This study attempts to delineate the biological mechanism of radiation-induced HBV reactivation.

EXPERIMENTAL DESIGN

Primary cultures of hepatocytes (PCC) were prepared from the noncancerous liver tissue removed perioperatively from 12 HBV carriers with hepatocellular carcinoma (HCC). The conditioned medium of irradiated PCCs, HCC, and endothelial cells from patients was transferred to PCCs or HepG2.2.15 cells (a human hepatoblastoma cell line transfected with HBV DNA) before subsequent irradiation. Forty-eight hours after irradiation, HBV DNA was measured by real-time quantitative PCR. Specific cytokines were determined by cytokine array and ELISA analysis. Preradiotherapy and postradiotherapy sera from 10 HBV carriers and 16 non-HBV carriers were analyzed for viral loads and cytokine activities.

RESULTS

Radiation induced HBV DNA replication in (a) irradiated PCCs cultured with the conditioned medium from irradiated PCCs (2.74-fold; P=0.004) and endothelial cells (9.50-fold; P=3.1x10(-10)), but not from HCCs (1.07-fold), and in (b) irradiated HepG2.2.15 cells (17.7-fold) cocultured with human umbilical vascular endothelial cells. Cytokine assay revealed increased expression of interleukin-6 (IL-6) in conditioned medium from irradiated human umbilical vascular endothelial cells. All 16 patients with liver irradiated had the increased serum IL-6 compared with 3 of 10 patients with irradiation excluding liver (P<0.001). All nine HBV carriers with liver irradiated had postradiotherapy increases in both HBV DNA and IL-6.

CONCLUSIONS

Radiation-induced liver toxicity with HBV reactivation is from a bystander effect on irradiated endothelial cells releasing cytokines, including IL-6.

Dynamic MRI signals in the second week of radiotherapy relate to treatment outcomes of hepatocellular carcinoma: a preliminary result

AIM

Radiotherapy (RT) has been used to treat hepatocellular carcinoma (HCC) in recent years. Despite its good local control, slow tumoral shrinkage and rapid recurrence compromise treatment outcomes. We evaluated the signal intensity of the hepatic parenchyma and tumours by using dynamic contrast enhanced magnetic resonance imaging (MRI) and correlated the findings with clinical outcomes. Nineteen patients with advanced HCC received 50 Gy in 25 fractions. They underwent a dynamic contrast-enhanced, turbo fast low-angle shot MR sequence at 1.5 T before therapy, at 2 weeks of therapy, and 1 month (week 9) later. Initial first-pass enhancement slopes (slope) and peak enhancement ratios (peak) were measured.

RESULTS

Initial signal intensities were not associated with RT outcomes. An increased slope and peak of the tumour at week 2 was associated with an improved local response (P<0.05). In the parenchyma, an increased slope at week 2 was associated with recurrence outside the radiation fields or with progression over distant sites (P<0.05). The differences in signal changes at week 2 during RT were not persistent at a statistically significant level at 1 month after RT.

CONCLUSION

Dynamic contrast-enhanced MRI signals may act as biomarkers for early prediction of responses to RT in patients with HCC. Signal intensities at week 2 are important in evaluating treatment outcomes.

Recommendations for radioembolization of hepatic malignancies using yttrium-90 microsphere brachytherapy: a consensus panel report from the radioembolization brachytherapy oncology consortium

PURPOSE

To standardize the indications, techniques, multimodality treatment approaches, and dosimetry to be used for yttrium-90 (Y90) microsphere hepatic brachytherapy.

METHODS AND MATERIALS

Members of the Radioembolization Brachytherapy Oncology Consortium met as an independent group of experts in interventional radiology, radiation oncology, nuclear medicine, medical oncology, and surgical oncology to identify areas of consensus and controversy and to issue clinical guidelines for Y90 microsphere brachytherapy.

RESULTS

A total of 14 recommendations are made with category 2A consensus. Key findings include the following. Sufficient evidence exists to support the safety and effectiveness of Y90 microsphere therapy. A meticulous angiographic technique is required to prevent complications. Resin microsphere prescribed activity is best estimated by the body surface area method. By virtue of their training, certification, and contribution to Y90 microsphere treatment programs, the disciplines of radiation oncology, nuclear medicine, and interventional radiology are all qualified to use Y90 microspheres. The panel strongly advocates the creation of a treatment registry with uniform reporting criteria. Initiation of clinical trials is essential to further define the safety and role of Y90 microspheres in the context of currently available therapies.

CONCLUSIONS

Yttrium-90 microsphere therapy is a complex procedure that requires multidisciplinary management for safety and success. Practitioners and cooperative groups are encouraged to use these guidelines to formulate their treatment and dose-reporting policies.

Stereotactic body radiation therapy for primary and metastatic liver tumors: A single institution phase i-ii study

The feasibility, toxicity and tumor response of stereotactic body radiation therapy (SBRT) for treatment of primary and metastastic liver tumors was investigated. From October 2002 until June 2006, 25 patients not suitable for other local treatments were entered in the study. In total 45 lesions were treated, 34 metastases and 11 hepatocellular carcinoma (HCC). Median follow-up was 12.9 months (range 0.5-31). Median lesion size was 3.2 cm (range 0.5-7.2) and median volume 22.2 cm3 (range 1.1-322). Patients with metastases, HCC without cirrhosis, and HCC < 4 cm with cirrhosis were mostly treated with 3 x 12.5 Gy. Patients with HCC > or =4 cm and cirrhosis received 5 x 5 Gy or 3 x 10 Gy. The prescription isodose was 65%. Acute toxicity was scored following the Common Toxicity Criteria and late toxicity with the SOMA/LENT classification. Local failures were observed in two HCC and two metastases. Local control rates at 1 and 2 years for the whole group were 94% and 82%. Acute toxicity grade > or =3 was seen in four patients; one HCC patient with Child B developed a liver failure together with an infection and died (grade 5), two metastases patients presented elevation of gamma glutamyl transferase (grade 3) and another asthenia (grade 3). Late toxicity was observed in one metastases patient who developed a portal hypertension syndrome with melena (grade 3). SBRT was feasible, with acceptable toxicity and encouraging local control. Optimal dose-fractionation schemes for HCC with cirrhosis have to be found. Extreme caution should be used for patients with Child B because of a high toxicity risk.

Stereotactic radiotherapy of primary liver cancer and hepatic metastases

The purpose was to evaluate the clinical results of stereotactic radiotherapy in primary liver tumors and hepatic metastases. Five patients with primary liver cancer and 39 patients with 51 hepatic metastases were treated by stereotactic radiotherapy since 1997. Twenty-eight targets were treated in a "low-dose"-group with 3 x 10 Gy (n = 27) or 4 x 7 Gy (n = 1) prescribed to the PTV-encl. 65%-isodose. In a "high-dose"-group patients were treated with 3 x 12 - 12.5 Gy (n = 19; same dose prescription) or 1 x 26 Gy/PTV-enclosing 80%-isodose (n = 9). Median follow-up was 15 months (2-48 months) for primary liver cancer and 15 months (2-85 months) for hepatic metastases. While all primary liver cancers were controlled, nine local failures (3-19 months) of 51 metastases were observed resulting in an actuarial local control rate of 92% after 12 months and 66% after 24 months and later. A borderline significant correlation between dose and local control was observed (p = 0.077): the actuarial local control rate after 12 and 24 months was 86% and 58% in the low-dose-group versus 100% and 82% in the high-dose-group. In multivariate analysis high versus low-dose was the only significant factor predicting local control (p = 0.0089). Overall survival after 1 and 2 years was 72% and 32% for all patients and was impaired due to systemic progression of disease. No severe acute or late toxicity exceeding RTOG/EORTC-score 2 were observed. Stereotactic irradiation of primary liver cancer and hepatic metastases offers a locally effective treatment without significant complications in patients, who are not amenable for surgery. Patient selection is important, because those with low risk for systemic progression are more likely to benefit from this approach.

Evaluation of the prognostic value of Okuda, Cancer of the Liver Italian Program, and Japan Integrated Staging systems for hepatocellular carcinoma patients undergoing radiotherapy

PURPOSE

The purpose of this study was to compare the validity of staging systems, as well as to identify the staging system with the best prognostic value, in hepatocellular carcinoma (HCC) patients treated with radiotherapy.

METHODS AND MATERIALS

From 1992 to 2003, a total of 305 patients undergoing radiotherapy for HCC were evaluated retrospectively. All patients were classified before radiation therapy by the following systems: tumor-node-metastasis (TNM), Okuda, Cancer of the Liver Italian Program (CLIP), and Japan Integrated Staging (JIS) score. Cumulative survival rates were obtained using the Kaplan-Meier method, and were statistically compared using the log-rank test.

RESULTS

Median survival time was 11 months. The 1-, 2-, 3-, 4-, and 5-year survival rates were 45.1%, 24.5%, 14.7%, 10.3%, and 6.4%, respectively. Significant differences in survival were observed between all TNM stages, between CLIP scores 2, 3 and 5, 6, as well as between JIS scores 1, 2, and 2, 3.

CONCLUSIONS

Among the systems studied, the TNM staging approach appeared to be the best predictor of prognosis. Staging systems that reflect liver disease status (Okuda stage, CLIP, and JIS score) showed limitations in stratifying patients undergoing radiotherapy into different prognostic groups.

Hypofractionated stereotactic body radiation therapy (SBRT) for limited hepatic metastases

PURPOSE

To evaluate the feasibility and efficacy of hypofractionated stereotactic body radiation therapy (SBRT) for the treatment of liver metastases.

METHODS AND MATERIALS

The records of 69 patients with 174 metastatic liver lesions treated with SBRT between April 2001 and October 2004 were reviewed. The most common primary tumors were colorectal (n = 20), breast (n = 16), pancreas (n = 9), and lung (n = 5). The mean number of lesions treated per patient was 2.5 (range, 1-6). The longest diameter of the lesions ranged in size from 0.6 to 12.2 cm (median, 2.7 cm). Dose per fraction ranged from 2 Gy to 6 Gy, with a median total dose of 48 Gy (range, 30-55 Gy). Dose was prescribed to the 100% isodose line (IDL), with the 80% IDL covering the gross tumor volume with a minimum margin of 7 mm.

RESULTS

The median follow up was 14.5 months. Sixty patients were evaluable for response based on an abdominal computed tomography scan obtained at a minimum of 3 months after completion of SBRT. The actuarial overall infield local control rate of the irradiated lesions was 76% and 57% at 10 and 20 months, respectively. The median overall survival time was 14.5 months. The progression-free survival rate was 46% and 24% at 6 and 12 months, respectively. None of the patients developed Grade 3 or higher toxicity.

CONCLUSION

Hypofractionated SBRT provides excellent local control with minimal side effects in selected patients with limited hepatic metastases.

A novel approach to brachytherapy in hepatocellular carcinoma using a phosphorous32 (32P) brachytherapy delivery device--a first-in-man study

PURPOSE

While potentially very useful, percutaneously delivered brachytherapy of inoperable intra-abdominal solid tumors faces significant technical challenges. This first-in-man study is designed to determine the safety profile and therapeutic efficacy of a novel phosphorous (32P) brachytherapy device (BrachySil) in patients with unresectable hepatocellular carcinoma.

METHODS AND MATERIALS

Patients received single percutaneous and transperitoneal implantations of BrachySil under local anesthesia directly into liver tumors under ultrasound or computed tomographic guidance, at an activity level of 4 MBq/cc of tumor. Toxicity was assessed by the nature, incidence, and severity of adverse events (Common Toxicity Criteria scores) and by hematology and clinical chemistry parameters. Target tumor response was assessed with computed tomographic scans at 12 and 24 weeks postimplantation using World Health Organization criteria.

RESULTS

Implantations were successfully carried out in 8 patients (13-74 MBq, mean 40 MBq per tumor) awake and under local anesthesia. Six of the 8 patients reported 19 adverse events, but no serious events were attributable to the study device. Changes in hematology and clinical chemistry were similarly minimal and reflected progressive underlying hepatic disease. All targeted tumors were responding at 12 weeks, with complete response (100% regression) in three lesions. At the end of the study, there were two complete responses, two partial responses, three stable diseases, and one progressive disease.

CONCLUSION

Percutaneous implantation of this novel 32P brachytherapy device into hepatocellular carcinoma is safe and well tolerated. A significant degree of antitumor efficacy was demonstrated at this low dose that warrants further investigation.

Stereotactic body radiation therapy for extracranial oligometastases: does the sword have a double edge?

Understanding the acute and chronic toxicities of stereotactic body radiation therapy (SBRT) for extracranial oligometastases might reveal treatment parameters that can be modulated to enhance the therapeutic ratio. Therefore, we searched PubMed from 1995 to 2005 for reports on stereotactic body radiation therapy, with emphasis on treatment of metastatic lesions of the lung and/or liver. Reports of SBRT for primary tumors of these sites were included to increase the number of evaluable patients. The reports were categorized by organ system and evaluated based on number of patients, number of lesions treated, dose fractionation scheme, and local control. A total of 15 lung studies (including 683 patients) and 7 liver studies (including 156 patients) were identified. Overall grade 3 to 5 toxicity was seen in up to 15% of patients in the lung SBRT studies and up to 18% of patients in the liver SBRT studies. Only 3 deaths were reported after SBRT of the liver and 2 after SBRT of the lung for treatment related mortality rates of 2% and 0.3%, respectively. No definitive relationship was found between radiation dose and toxicity. Conversely, radiation treatment volume may be associated with the infrequent toxicities that occur. The literature supports SBRT as a safe and effective treatment for oligometastases of the liver and lung. Further studies are needed to define the optimal dose and fractionation schedule.

Dose as a function of liver volume and planning target volume in helical tomotherapy, intensity-modulated radiation therapy-based stereotactic body radiation therapy for hepatic metastasis

PURPOSE

Stereotactic body radiation therapy (SBRT) has been shown to be an effective, well-tolerated treatment for local control of tumors metastatic to the liver. Multi-institutional Phase II trials are examining 60 Gy in 3 fractions delivered by linac-based, 3D-conformal IMRT. HiArt Helical TomoTherapy is a treatment unit that delivers co-planar helical IMRT that is capable of image-guided SBRT. We hypothesized that the maximum tolerable dose (MTD) delivered to a lesion by Helical TomoTherapy-based SBRT could be predicted based on the planning target volume (PTV) and liver volume.

METHODS AND MATERIALS

To test this, we performed inverse treatment planning and analyzed the dosimetry for multiple hypothetical liver gross tumor volumes (GTV) with conventional PTV expansions. Inverse planning was carried out to find the maximum tolerated SBRT dose up to 60 Gy to be delivered in 3 fractions based on the dose constraint that 700 cc of normal liver would receive less than 15 Gy.

RESULTS

Regression analysis indicated a linear relationship between the MTD, the PTV and the liver volume, supporting our hypothesis. A predictive equation was generated, which was found to have an accuracy of +/-3 Gy. In addition, dose constraints based on proximity to other normal tissues were tested. Inverse planning for PTVs located at varying distances from the heart, small bowel, and spinal cord revealed a predictable decrease in the MTD as the PTV increased in size or approached normal organs.

CONCLUSIONS

These data provide a framework for predicting the likely MTD for patients considered for Helical TomoTherapy liver SBRT.

Radiation-induced liver disease in three-dimensional conformal radiation therapy for primary liver carcinoma: the risk factors and hepatic radiation tolerance

PURPOSE

To identify risk factors relevant to radiation-induced liver disease (RILD) and to determine the hepatic tolerance to radiation.

METHODS AND MATERIALS

The data of 109 primary liver carcinomas (PLC) treated with hypofractionated three-dimensional conformal radiation therapy (3D-CRT) were analyzed. Seventeen patients were diagnosed with RILD and 13 of 17 died of it.

RESULTS

The risk factors for RILD were late T stage, large gross tumor volume, presence of portal vein thrombosis, association with Child-Pugh Grade B cirrhosis, and acute hepatic toxicity. Multivariate analyses demonstrated that the severity of hepatic cirrhosis was a unique independent predictor. For Child-Pugh Grade A patients, the hepatic radiation tolerance was as follows: (1) Mean dose to normal liver (MDTNL) of 23 Gy was tolerable. (2) For cumulative dose-volume histogram, the tolerable volume percentages would be less than: V5 of 86%, V10 of 68%, V15 of 59%, V20 of 49%, V25 of 35%, V30 of 28%, V35 of 25%, and V40 of 20%. (3) Tolerable MDTNL could be estimated by MDTNL (Gy) = -1.686 + 0.023 * normal liver volume (cm3).

CONCLUSION

The predominant risk factor for RILD was the severity of hepatic cirrhosis. The hepatic tolerance to radiation could be estimated by dosimetric parameters.

Retrospective Study of Capecitabine and Celecoxib In Metastatic Colorectal Cancer

OBJECTIVE

COX-2 activation may mediate capecitabine induced toxicities, eg, hand-foot syndrome (HFS) and colorectal cancer progression, both of which may be improved by concurrent celecoxib.

PATIENTS AND METHODS

From October 2000 to December 2003, 66 patients with metastatic colorectal cancer received concurrent capecitabine at 1000 mg/m/d b.i.d. and celecoxib at 200 mg b.i.d. (XCEL). Twenty-four patients were chemo-naive, 42 patients were second-line; while 34 had XCEL with radiation.

RESULTS

The median duration of XCEL was 7.2 months (range, 1.5-38 months). Ninety percent of Grade 2/3 HFS (17%) occurred after 6 months and incidence of grade 3/4 diarrheas was 8%. The overall response rate was 38% (95% confidence interval [CI], 26-51%), with 11 patients (17%) achieving complete responses and 2 patients (3%) with near complete responses. Six patients (9%) become resectable after sustaining treatment response. The median progression-free survival (PFS) and overall survival (OS) was 8.3 months (95% CI, 7.0-11.0 months) and 22 months (95% CI, 17.8-31.5 months), respectively. Improved median PFS of 14.5 months (P = 0.0001) and OS of 31.5 months (P = 0.005) were noted in patients with normal lactate dehydrogenase (LDH) levels (n = 37) than patients with high levels of LDH (n = 29).

CONCLUSIONS

XCEL integrating radiation may improve response rate and survival and reduce toxicities, notably HFS for patients with metastatic colorectal cancer, leading to a randomized phase III study.

Radiation therapy for hepatocellular carcinoma: from palliation to cure

Technologic advances have provided the means to deliver tumoricidal doses of radiation therapy (RT) to patients with unresectable hepatocellular carcinoma (HCC) while avoiding critical normal tissues, providing the opportunity to use RT for curative intent treatment of HCC. For the current report, the expanded role of external beam RT in the setting of HCC from palliation to cure was reviewed. A systematic literature search was undertaken using the MEDLINE data base and secondary references to identify peer-reviewed, English-language articles that reported clinical outcomes after external beam RT alone or in combination with other treatments for HCC. Abstracts from the 2005 American Society of Clinical Oncology, American Society for Therapeutic Radiology and Oncology, American Gastrointestinal Association, and Society of Surgical Oncology Gastrointestinal Cancer Symposium also were included in the search. More than 60 articles reporting on clinical outcomes among patients who received RT for HCC have been published since 1990, including 20 articles that described unique sets of at least 15 patients. RT was used for palliation, to improve local control, and with curative intent in a wide spectrum of patients who most often were unsuitable for surgery and other treatments. Pain reduction following RT was noted in approximately 75% of patients with bone metastases from HCC who received RT. For patients with liver-confined disease treated with conformal RT, proton beam RT, and/or image guided RT with or without transarterial chemoembolization (TACE), local control response rates ranged from 40% to 90%, and the median survival ranges from 10 months to 25 months. For patients with HCC who had portal vein thrombus, the median survival after RT to treat the thrombus and/or the hepatic tumor with or without TACE ranged from 5.3 months to 9.7 months. Although outcomes after high-dose conformal RT for liver-confined HCC were excellent, the potential survival benefit of RT should be tested in randomized controlled trials that require international collaboration.

Advances in radiation oncology

Advances in radiation oncology have been made on three major fronts: biology, physics, and clinical application. Our biological understanding of how radiation kills cells and how malignant cells avoid damage has identified new targets for therapeutic manipulation. Research in physics has yielded sophisticated methods to direct the deposition of radiation energy in ways that enhance target coverage while minimizing dose to normal structures as much as possible. Intensity-modulated radiation therapy (IMRT) and image-guided radiation therapy represent new paradigms in treatment planning and dose delivery. Clinical management of the cancer patient is multidisciplinary. Increasingly, combinations of radiation and chemotherapy, with or without surgery, are enhancing cure rates, often with preservation of organ function. Taken together, these advances have increased the effectiveness of radiation therapy and promise better treatment results in the future.

Phase II trial of high-dose conformal radiation therapy with concurrent hepatic artery floxuridine for unresectable intrahepatic malignancies

PURPOSE

A phase II trial was conducted to determine if high-dose radiation with concurrent hepatic arterial floxuridine would improve survival in patients with unresectable intrahepatic malignancies.

PATIENTS AND METHODS

Three-dimensional conformal high-dose radiation therapy was delivered concurrently with hepatic arterial floxuridine in 128 patients. The radiation dose was based on a normal-tissue complication probability model and subjected the patient to an estimated maximum risk of radiation-induced liver disease of 10% to 15%. The study design provided more than 80% power to detect a two-fold increase in median survival compared with historical controls at a 5% significance level.

RESULTS

The median radiation dose delivered was 60.75 Gy (1.5-Gy fractions bid). At a median follow-up time of 16 months (26 months in patients who were alive) the median survival was 15.8 months (95% CI, 12.6 to 18.3 months), significantly longer than in the historical control. The actuarial 3-year survival was 17%. The total dose was the only significant predictor of survival. Primary hepatobiliary tumors had a significantly greater tendency to remain confined to the liver than did colorectal cancer metastases. Overall toxicity was acceptable, with 27 patients (21%) and 11 patients (9%) developing grade 3 and 4 toxicity, respectively, and one treatment-related death.

CONCLUSION

The results suggest that, compared with historical controls, high-dose focal liver irradiation with hepatic artery floxuridine prolongs survival in patients with unresectable chemotherapy-refractory metastatic colorectal cancer and primary hepatobiliary tumors. This provides a rationale for intensification of local therapy for unresectable hepatobiliary cancers and integration of this regimen with newer systemic therapy for patients with colorectal cancer.

Local radiotherapy as a complement to incomplete transcatheter arterial chemoembolization in locally advanced hepatocellular carcinoma

PURPOSE

In order to determine the effect of additional radiotherapy (RT) after an incomplete transcatheter arterial chemoembolization (TACE) in an unresectable hepatocellular carcinoma (HCC), the treatment results of patients receiving TACE plus RT were analyzed and compared with those treated with TACE alone.

MATERIALS AND METHODS

One hundred and five patients with an unresectable HCC were treated with TACE from January 1992 to December 2002. In 73 of these patients, the TACE was incomplete. Among them, TACE was repeatedly performed in 35 patients (TACE group), and the remaining 38 patients were also treated with local RT (TACERT group). The patients were either in stage III or IVa, Eastern Cooperative Oncology Group 2 or less, and Child-Pugh class A or B. The average frequency of TACE prior to RT was 2 and the RT was started within 7-10 days after the TACE.

RESULTS

The 2-year survival rate was significantly higher in the TACERT than in the TACE group (36.8 % vs. 14.3%, P=0.001). According to the tumor size, the 2-year survival rates in the TACERT and TACE groups were 63% vs. 42% in 5-7 cm (P=0.22), 50% vs. 0% in 8-10 cm (P=0.03), and 17% vs. 0% in larger than 10 cm (P=0.0002) respectively.

CONCLUSION

There was a significantly improved survival rate in the TACERT group of unresectable HCC patients than in the TACE group, particularly in case of tumors > or =8 cm in diameter. Therefore, RT in addition to TACE is strongly recommended for patients with an unresectable HCC.

Retrospective Clinicopathologic Correlation of Gross Tumor Size of Hepatocellular Carcinoma

PURPOSE

To determine the degree of correlation between radiographic size and true gross pathologic size for subjects with primary hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

This analysis included 18 patients with 27 tumors who underwent either partial hepatectomy or orthotopic liver transplantation for HCC at the University of Colorado Hospital between 1997 and 2002. Preoperative imaging was performed using computed tomography (CT) or magnetic resonance imaging (MRI). After surgical resection the size of each tumor on gross pathologic examination was recorded. The maximal measurement in one dimension on axial imaging and pathologic examination was extracted for statistical analysis. The clinical and pathologic sizes were compared using a percent size difference (%Deltasize) as an end point for each patient. A regression analysis was applied to study the association between pathologic and clinical size.

RESULTS

The median radiographic size was 2.90 cm (range 1.2-4.9). The median pathologic size was 2.50 cm (range 1-4.8). The radiographic size was larger than or equal to the pathologic size in 22/27 tumors (81%) and smaller in 5/27 (19%) tumors. The median %Deltasize was 17.5% (range -20-144%). Overall, the radiographic and pathologic sizes were positively correlated (r = 0.8). This correlation was not affected by choice of imaging modality (CT versus MRI, P = 0.71) or time of preoperative imaging (0-4 weeks versus 4-8 weeks before surgery, P = 0.61).

CONCLUSIONS

Our study shows that in most instances (81%), imaging by CT or MRI overestimates true gross pathologic size of HCC. Nineteen percent of tumors appeared smaller on preoperative imaging than on the final pathologic specimen. Radiation therapy utilizing a 0.5 or 1.0 cm margin around the radiographic tumor would have encompassed the gross pathologic tumor in 93% and 100% of cases, respectively.

Tolérance et efficacité de la radiothérapie de conformation en cas de carcinome hépatocellulaire chez le patient cirrhotique. Résultats de l'essai de phase II RTF1

PURPOSE

While some patients presenting with hepatocellular carcinoma (HCC) benefit from curative therapies (transplantation, surgery, percutaneous ablation), others are only candidates for palliative options such as chemoembolization or symptomatic care. Although conventional external-beam radiotherapy of the liver is regarded as little efficient and potentially toxic in cirrhotic patients, 3-dimensional conformal radiotherapy (CRT), by decreasing the amount of normal liver included in the radiation portal, allows dose escalation to occur without increasing the risk of radiation-induced hepatitis. This trial was designed to assess the efficacy and tolerance of CRT for small-size HCC in cirrhotic patients.

PATIENTS AND METHODS

Prospective phase II trial including stage A/B cirrhotic patients with small-size HCC not suitable for curative treatments; CRT consisted in a standard fractionation radiation, with a total dose of 66 Gy.

RESULTS

Twenty-seven patients were included, 15 of whom had previously been treated for HCC; mean age was 68. Among the 23 assessable patients, 18 (78%) presented with complete response, 3 (13%) with partial response, and 2 with no response. Acute complications occurred in 24 patients, and were mainly acceptable (grade 1/2: 22 patients, grade 3/4: 11 patients, 4 (15%) of whom had clinical and/or hematological toxicities). Only 2 (9%) grade 3/4 clinical and/or hematological late toxicities are reported.

CONCLUSION

CRT is a non-invasive curative technique highly suitable for small-size HCC in cirrhotic patients; further investigations are needed to compare it to the other available treatments, and to integrate it into the curative therapeutic algorithm of HCC.

Chemoradiation and brachytherapy in biliary tract carcinoma: long-term results

PURPOSE

To evaluate long-term effects of chemoradiation and intraluminal brachytherapy in terms of local control, disease-free survival, overall survival, and symptom relief in patients with unresectable or residual extrahepatic biliary carcinoma.

METHODS AND MATERIALS

Twenty-two patients with unresectable (17 patients) or residual (5 patients) nonmetastatic extrahepatic bile tumors received external beam radiation therapy (39.6-50.4 Gy) between 1991 and 1997. In 21 patients, 5-fluorouracil (96-h continuous infusion, Days 1-4, 1,000 mg/m2/day) was administered. Twelve patients received a boost of intraluminal brachytherapy with 192Ir wires (30-50 Gy) 1 cm from the source axis.

RESULTS

During external beam radiotherapy, 10 patients (45.4%) developed Grade 1 to 2 gastrointestinal toxicity. In patients with unresectable tumor who could be evaluated, the clinical response was 28.6% (4 of 14). Two patients showed complete response. In all 22 patients, median durations of local control, disease-free survival, and overall survival were 44.5 months, 16.3 months, and 23.0 months, respectively. Two patients who received external beam radiation therapy and intraluminal brachytherapy developed late duodenal ulceration. In patients with unresectable tumors, median survival was 13.0 months and 22.0 months in those treated with and without brachytherapy, with 16.7% and no 5-year survival, respectively (p=0.607). Overall 5-year survival was 18.0%: 40% and 11.7% in patients treated with partial resection and in those with unresectable tumor, respectively (p=0.135).

CONCLUSION

This study confirmed the role of concurrent chemoradiation in advanced biliary carcinoma; the role of intraluminal brachytherapy boost remains to be further analyzed in larger clinical trials.

Inclusion of biological factors in parallel-architecture normal-tissue complication probability model for radiation-induced liver disease

PURPOSE

To include biologic factors in parallel-architecture normal-tissue complication probability (NTCP) model for radiation-induced liver disease (RILD) after three-dimensional conformal radiotherapy (3D-CRT) for gastric or hepatic cancer.

METHODS AND MATERIALS

A total of 151 patients (89 with hepatocellular carcinoma and 62 with gastric cancer) who received 3D-CRT to the liver were included (isocenter dose range 33.0 to 66.0 Gy; mean 48.0 Gy). RILD was defined as grade 3 or higher liver toxicity according to Common Toxicity Criteria Version 2.0 of the National Cancer Institute within 4 months after 3D-CRT. Possible correlations of patient-related or dosimetric factors with RILD were tested. Maximum-likelihood analysis estimated NTCP model parameters for group and subgroups. Goodness-of-fit analysis estimated deviance of NTCP model parameters between subgroups.

RESULTS

RILD developed in 25 patients. Hepatitis B virus carrier status (p < 0.001) was the only significant independent factor. The 4 parallel NTCP model parameters, mean functional reserve (V(50)), width of functional reserve distribution (sigma), dose damage to 50% of liver subunits (D(50)), and slope parameter for subunit dose-response (k), were respectively, 0.54, 0.14, 50 Gy, 0.18 (group); 0.53, 0.07, 50 Gy, 4.6 x 10(-7) (carriers); 0.59, 0.12, 25 Gy, 59.8 (noncarriers). In carrier-state subgroups, goodness-of-fit deviance with 1 subgroup's parameter set would have been worse in the other group. Across subgroups, patients with RILD all had liver fraction damage (f) greater than 0.4 compared with wider distribution for the whole group.

CONCLUSIONS

RILD is described with a parallel-architecture NTCP model for HBV carriers and noncarriers with a threshold effect greater than 0.4. The main difference is in slope parameter for subunit dose-response.

Hypofractionated three-dimensional conformal radiation therapy for primary liver carcinoma

BACKGROUND

The purpose of the current study was to evaluate the tolerance and efficacy of hypofractionated three-dimensional conformal radiotherapy (3DCRT) with or without transarterial chemoembolization (TACE) for technically unresectable or medically inoperable primary liver carcinoma (PLC).

METHODS

Between April 1999 and August 2003, 128 patients with a clinical diagnosis of PLC received hypofractionated 3DCRT at Cancer Hospital, Guangxi Medical University. Both hypofractionated 3DCRT and TACE were used to treat 48 of these 128 patients. Liver cirrhosis of Child-Pugh Grade A was found in 108 patients, and Grade B was found in 20 patients. The mean gross tumor volume (GTV) was 459 +/- 430 cm3. A mean total irradiation dose of 53.6 +/- 6.6 Gy was delivered at an average fraction of 4.88 +/- 0.47 Gy, 3 times a week using 8-MV photons.

RESULTS

The median follow-up time after 3DCRT was 12 months (range, 2-56 mos.). The immediate response rate was 55%. The overall survival rates at 1, 2, and 3 years were 65%, 43%, and 33%, respectively, with a median survival of 20 months (range, 7-31 mos.). Radiation Therapy Oncology Group (RTOG) Grade 2 acute gastrointestinal complications developed in 8 patients, whereas 4 patients developed Grade 3 late gastrointestinal complications. Radiation-induced liver disease (RILD) developed in 19 (15%) patients, of which 12 had Child-Pugh Grade B liver cirrhosis, and 7 had Grade A. GTV and associated liver cirrhosis were identified by Cox regression analysis as independent predictors for survival (P = 0.044 and 0.015).

CONCLUSIONS

Hypofractionated 3DCRT is effective in carefully selected patients with PLC. Gastrointestinal complications and RILD were the most distinct complications.

Benefit of using biologic parameters (EUD and NTCP) in IMRT optimization for treatment of intrahepatic tumors

PURPOSE

To investigate whether intensity-modulated radiotherapy (IMRT), optimized using the generalized equivalent uniform dose (gEUD) and normal tissue complication probability (NTCP) models, can increase the safe dose to intrahepatic tumors compared with three-dimensional conformal RT (3D-CRT). A secondary objective was to investigate the optimal beam arrangement for liver IMRT plans.

METHODS AND MATERIALS

Planning CT data of 15 patients with intrahepatic tumors, previously treated with 3D-CRT, were used as input. The dose delivered using 3D-CRT had been limited either by tolerance of adjacent organs, which were close to, or overlapped with, the planning target volume (PTV; overlap cases, n = 8), or liver toxicity (nonoverlap, n = 7). IMRT plans were created using the gEUD to maximize the dose across the PTV and the NTCP to maintain the organ-at-risk toxicity to that of the conformal plan. Increased heterogeneity was allowed across the PTV in overlap cases, without compromising the minimal PTV dose of the conformal plan and restricting the maximal dose to within 110% of the mean. Three different beam arrangements were used for each case: seven-field equidistant axial, six-field noncoplanar (predominantly right-sided beams), and a reproduction of the conformal gantry angles. gEUDs were also computed and used for evaluation of the plans (regardless of planning technique) to reflect the response of both high- and low-grade tumors. The IMRT plan that allowed the greatest gEUD across the PTV was used in the comparison with the 3D-CRT plan.

RESULTS

The use of IMRT significantly increased the maximal gEUD achievable across the PTV compared with the 3D-CRT plans. This was the case for the assumptions of both high- and low-grade tumors, irrespective of the tumor position within the liver. The mean gEUD increase was 11 Gy (high grade) and 18.0 Gy (low grade) for overlap cases (p = 0.001 and p = 0.003, respectively) and 10 Gy for nonoverlap cases (p = 0.020). When comparing the IMRT beam arrangements, gEUDs were considered equivalent if they differed by less than one fraction (1.5 Gy). In overlap cases (n = 8), an equivalent "best" gEUD value was obtained in 3, 5, and 7 cases for the original conformal angle, seven-field axial, and six-field noncoplanar plan, respectively. The corresponding results were 5, 2, and 3 in the cases without an overlap (n = 7).

CONCLUSION

We have successfully used mathematical/biologic models directly as cost functions within the optimizing process to produce IMRT plans that maximize the gEUD while maintaining compliance with a well-defined protocol for the treatment of intrahepatic cancer. For both PTV-organ-at-risk overlap and nonoverlap situations, IMRT has the capacity to improve the maximal dose achievable across the PTV, expressed in terms of the gEUD. The use of multiple noncoplanar beams appears to confer an advantage over fewer beams in cases with PTV-organ-at-risk overlap. When liver toxicity is the dose-limiting factor, high gEUD values are obtained most frequently when the field arrangement is chosen to provide the shortest possible transhepatic path length.

Local radiotherapy for patients with unresectable hepatocellular carcinoma

PURPOSE

To evaluate the response to local radiotherapy (RT) for unresectable hepatocellular carcinoma (HCC) and to analyze the dose-response relationship and the treatment-related morbidities.

METHODS AND MATERIALS

Between 1998 and 2002, 59 patients who were treated with localized RT were evaluated. RT was delivered with a curative intent, and the radiation dose was 30-55 Gy (biologic effective dose of 39.0-70.2 Gy(10) using the alpha/beta ratio of 10 Gy) with 2-3 Gy as a daily dose. The tumor response was evaluated by the change in maximum tumor size on serial CT scans, and the morbidity was evaluated by the Common Terminology Criteria for Adverse Events v3.0.

RESULTS

An objective tumor response was achieved in 39 of 59 patients (66.1%) with complete response (CR) in 5 patients and partial response (PR) in 34 patients. More than 50 Gy(10) had a significant response; CR or PR was 72.8% with >50 Gy(10) and 46.7% with < or =50 Gy(10) (p = 0.0299). The 2-year overall survival rate after RT was 27.4% (median survival time: 10 months), and this was affected by the tumor response (p = 0.0640); the 2-year overall survival rate after RT was 50.0% for CR and 21.8% for PR. There was no Grade 3 or 4 acute toxicity, and 3 patients (5.1%) developed gastric or duodenal ulcer.

CONCLUSIONS

Radiotherapy for unresectable HCC resulted in 66.1% of tumor response with acceptable toxicity, and the radiation dose seems to be a significant prognostic factor in RT response for HCC.

Biologic susceptibility of hepatocellular carcinoma patients treated with radiotherapy to radiation-induced liver disease

PURPOSE

To identify the factors associated with radiation-induced liver disease (RILD) and to describe the difference in normal tissue complication probability (NTCP) between subgroups of hepatocellular carcinoma patients undergoing three-dimensional conformal radiotherapy (3D-CRT).

METHODS AND MATERIALS

A total of 89 hepatocellular carcinoma patients who completed 3D-CRT for local hepatic tumors were included. The average isocenter dose was 49.9 +/- 6.2 Gy. Logistic regression analysis was used for the association between statistically significant factors and RILD (defined as Grade 3 or 4 hepatic toxicity of elevated transaminases or alkaline phosphatase within 4 months of completing 3D-CRT) in multivariate analysis. Maximal likelihood analysis was conducted to obtain the best estimates of the NTCP model parameters.

RESULTS

Of the 89 patients, 17 developed RILD. In univariate analysis, hepatitis B virus (HBV)-positive status and the mean radiation dose to the liver were the two factors significantly associated with the development of RILD. Of the 65 patients who were HBV carriers, 16 had RILD compared with 1 of 24 non-carrier patients (p = 0.03). The mean radiation dose to liver was significantly greater in patients with RILD (22.9 vs. 19.0 Gy, p = 0.05). On multivariate analysis, HBV carrier status (odds ratio, 9.26; p = 0.04) and Child-Pugh B cirrhosis of the liver (odds ratio, 3.65; p = 0.04) remained statistically significant. The best estimates of the NTCP parameters were n = 0.35, m = 0.39, and TD(50)(1) = 49.4 Gy. The n, m, TD(50)(1) specifically estimated from the HBV carriers was 0.26, 0.40, and 50.0 Gy, respectively, compared with 0.86, 0.31, and 46.1 Gy, respectively, for non-carrier patients.

CONCLUSION

Hepatocellular carcinoma patients who were HBV carriers or had Child-Pugh B cirrhosis presented with a statistically significantly greater susceptibility to RILD after 3D-CRT.

Pathologic response and microdosimetry of (90)Y microspheres in man: review of four explanted whole livers

INTRODUCTION

Radioactive microsphere (90)Y therapy is increasingly used for primary and metastatic solid tumors in the liver. We present an analysis of 4 explanted livers previously treated with (90)Y microsphere agents (glass or resin). One tumor nodule was analyzed with submillimeter three-dimensional microdosimetry.

METHODS AND MATERIALS

Four patients received hepatic artery delivery of (90)Y microspheres for unresectable hepatocellular and colon cancers. Whole livers were explanted as part of lifesaving cadaveric transplant in 2 patients with hepatoma. These patients had received glass microspheres as a procedural bridge to transplant. Autopsy was performed on 2 patients with colon cancer who died of progressive metastatic disease and who had been treated with resin microspheres. Complete pathologic review was performed on each whole liver, including estimation of the response of the tumor to therapy, distribution of microspheres in the tumor and normal liver tissues, and normal-tissue radiation response. A biopsy taken from the edge of a tumor nodule was sectioned serially for three-dimensional radiation dosimetry analyses. Three-dimensional microsphere coordinates within the biopsy specimen were used to calculate dosage using a three-dimensional dose kernel. Isodose coverage of tumor and normal liver areas and total dose delivered were determined.

RESULTS

Preferential and heterogeneous deposition of microspheres was noted at the edge of tumor nodules compared with the center portion of the tumor or normal liver parenchyma. Both glass and resin microspheres delivered high cumulative doses to the tumor, which varied from 100 Gy to more than 3000 Gy. No veno-occlusive disease or widespread radiation hepatitis was seen.

CONCLUSION

Microsphere ((90)Y) therapy delivers high numbers of spheres with resulting high total doses of radiation, preferentially in the periphery of tumors. Normal liver parenchyma showed little radiation effect away from the tumors. Heterogeneous high-dose regions in the tumor were produced by both glass and resin microspheres.

External beam radiation therapy for hepatocellular carcinoma: potential of intensity-modulated and image-guided radiation therapy

External beam radiotherapy has historically played a minor role in the primary treatment of hepatocellular carcinoma. Although there is evidence for tumor response to external beam radiotherapy and despite the fact that a radiation dose-response relationship has been established, the limited radiation tolerance of the adjacent normal liver has prohibited wider use of radiation therapy in this disease. Recent technological and conceptual developments in the field of radiation therapy-such as intensity-modulated radiation therapy, image-guided radiation therapy, and stereotactic body radiation therapy-have the potential to improve radiation treatments by conforming the delivered radiation dose distribution tightly to the tumor or target volume outline while sparing normal liver tissue from high-dose radiation. Image guidance allows for a reduction of added (normal tissue) safety margins designed to account for interfraction patient and target setup variability, and stereotactic targeting will further reduce residual target setup uncertainty. Combining improvements in tumor targeting with normal tissue sparing, radiation dose delivery will enable clinically effective and safe radiation delivery for liver tumors such as hepatocellular carcinoma. This article reviews the role of radiotherapy for hepatocellular carcinoma; presents modern radiation therapy modalities and concepts such as intensity-modulated, image-guided, and stereotactic body radiation therapy; and hypothesizes about their future effect on primary treatment alternatives.

The role of radiotherapy in the treatment of liver metastases

Radiotherapy has historically played a minor role in the treatment of patients with unresectable liver metastases from colorectal cancer and other malignancies. This can be attributed chiefly to the low tolerance of the whole liver to radiation. High-precision radiotherapy planning techniques have allowed much higher doses of radiation to be delivered safely to focal liver metastases, while sparing most of the normal liver. When combined with hepatic arterial fluorodeoxyuridine, high-dose focal liver radiotherapy is associated with excellent response rates, local control, and survival in patients with unresectable liver metastases from colorectal cancer. Radiotherapy, with and without concurrent systemic chemotherapy, has also been used with encouraging outcomes for patients with liver metastases from colorectal cancer and other cancers. There appears to be a radiation dose response for liver metastases; tumors treated with doses of 70 Gy or greater are likelier to have durable local control. Advancements in tumor imaging, in radiotherapy techniques that will allow the safe delivery of higher doses of radiation, and in novel tumor radiation sensitizers and normal tissue radioprotectors should substantially improve the outcome of patients with unresectable liver metastases treated with radiotherapy.

A method for incorporating organ motion due to breathing into 3D dose calculations in the liver: sensitivity to variations in motion

Organ motion has been previously described using a probability distribution function that depends solely upon the amplitude of motion and the degree of asymmetry in the breathing cycle, and that function has been used with patient specific parameters to correct static dose distributions for patient breathing using a dose convolution method. In this study, the consequences of errors in the selection of those two parameters were evaluated. Patients previously treated using a focal liver dose escalation protocol were selected with tumors located in the superior or inferior portion of the liver. For a fixed degree of asymmetry (amplitude), the amplitude (asymmetry) of motion was varied about its nominal value and the consequences of organ motion on the dose distribution and the (potentially new) prescription dose were evaluated. These comparisons show that small (+/- 3 mm) variations of the amplitude of motion about the nominally measured value may not result in clinically significant changes (< a single fraction change in the prescription dose), however, larger variations (> 5 mm) can lead to significant changes. Assuming from measurement that the patient breathes asymmetrically (spends more time at expiration), variations in the assumed degree of asymmetry rarely lead to clinically significant changes; the most significant cause for concern being when the patient breathing cycle is maximally different from the treatment planning case (e.g., patient assumed to spend more time at expiration, but later breaths symmetrically). The results point out where quality assurance efforts should be concentrated to help assure the validity of the assumptions used to correct the static dose distributions for patient breathing using the convolution method.

Alterations in normal liver doses due to organ motion

PURPOSE

To assess the clinical significance of differences between treatment planning calculations based on static computed tomography (CT) and more realistic predictions of the actual delivered dose to intrahepatic lesions by a geometric convolution approach that accounts for random setup variations and breathing-induced organ motion.

MATERIALS AND METHODS

We recalculated target and normal liver doses for 40 patients previously treated on a conformal therapy dose escalation protocol to include the effect of setup uncertainties and liver motion due to patient breathing. Initial three-dimensional (3D) dose calculations based on pretreatment CT scans taken with voluntary breath-hold at normal exhalation were convolved with 3D anisotropic probability distribution functions reflecting population measurements of position setup variation. The convolution also included a distribution function (one-dimensional, inferior-superior direction only) representing the asymmetric temporal pattern (biased toward exhalation, based on population measurements) of a typical breathing cycle, scaled in amplitude for each patient.

RESULTS

After convolution, the minimum clinical target volume (CTV) dose met or exceeded the minimum planning target volume (PTV) dose from the static plan in all but one case, indicating adequate PTV design. However, clinically relevant and statistically significant increases (decreases) in liver normal tissue complication probability (NTCP) from values computed for the static cases occurred for tumors located toward the bottom (top) of the liver, as predicted for these patients scanned at exhalation. The change in liver NTCP (from a nominal 20%) ranged from +12.0% to -11.7% (average magnitude change 3.9% [sigma = 3.3%]). Changes in prescription dose required to restore the original 20% NTCP ranged from -3.7 Gy to +7.9 Gy (average magnitude change 1.9 Gy [sigma = 1.9 Gy]).

CONCLUSIONS

Although the PTV concept can ensure adequate CTV coverage, the doses to normal liver are incorrectly modeled without including patient-related geometric uncertainties.

Conformal chemoradiation for primary and metastatic liver malignancies

Historically, radiation therapy has played a minor role in the management of patients with unresectable primary hepatobiliary malignancies and liver metastases from colorectal cancer. This can be attributed chiefly to the low tolerance of the whole liver to radiation. Three-dimensional radiation planning techniques have allowed much higher doses of radiation to be delivered to focal liver tumors, while sparing the majority of the normal liver. When combined with fluorodeoxyuridine (FUdR), high-dose focal liver radiation is associated with excellent response rates, local control, and survival in patients with large unresectable tumors. There appears to be a radiation dose response for intrahepatic malignancies. Advancements in tumor imaging, radiation techniques that can safely deliver higher doses of radiation, novel tumor radiation sensitizers, and normal-tissue radioprotectors should substantially improve the outcome of patients with unresectable intrahepatic malignancies treated with chemoradiation.

Lethal hepatic injury by combined treatment of radiation plus chemotherapy in rats with thioacetamide-induced liver cirrhosis

PURPOSE

To assess lethal hepatic injury by combined treatment of radiation (RT) plus chemotherapy in a rat model with thioacetamide (TAA)-induced liver cirrhosis.

METHODS AND MATERIALS

Male Wistar rats were treated with 0.3 g/L TAA in drinking water. The development of liver cirrhosis was histologically confirmed, and the degree of liver function impairment was assessed by indocyanine green retention test (ICG R15). The established cirrhotic rats were given one of the following treatments: partial liver radiotherapy (25 Gy on about one-third of the whole liver), 5-fluorouracil (5-FU) chemotherapy (50 mg/kg), and combined treatment of partial RT plus 5-FU. The treated rats were closely followed until either death or 30 weeks after the treatment, and the postmortem liver sampling was examined for lethal hepatic injury by the treatments.

RESULTS

The rats developed overt liver cirrhosis after 30 weeks of TAA treatment. At that time, the mean ICG R15 level in the TAA-treated rats (TAA-rats) was 14.1% +/- 0.7% compared to 4.6% +/- 0.7% in the control (p < 0.05). The 30-week survival rates in the control and TAA-rats were 100% (5/5) and 75% (6/8), respectively, after partial liver RT (p = 0.72). In the 5-FU chemotherapy group, the survival in TAA-rats was only one-half of that in the controls (100% vs. 50%, p = 0.06). Poor survival in TAA-rats was shown also in the combined group of partial RT plus 5-FU (87.5% vs. 16.7%, p = 0.06). The rats that died before the last observation time showed advanced cirrhosis with areas of lobular collapse, in contrast to the moderate cirrhotic features in those that survived.

CONCLUSION

In a rat cirrhosis model with mildly impaired liver function, combined treatment of partial RT plus 5-FU resulted in significantly high incidence of lethal liver injury. The results in this study show that a combined treatment of RT plus chemotherapy in cirrhotic patients should be applied with extreme caution.

Ionizing radiation increases adenovirus uptake and improves transgene expression in intrahepatic colon cancer xenografts

Specific targeting and transgene expression in tumors are critical in adenovirus gene therapy for intrahepatic colon carcinoma metastases. In this study, we investigated if ionizing radiation could increase adenoviral uptake by cells. Various human cell lines and rat hepatocytes were irradiated prior to exposure to a cytomegalovirus (CMV) promoter-driven green fluorescent protein (GFP) marker gene adenoviral vector. We found that gamma-radiation increased the number of GFP-positive cells in a dose- and time-dependent manner for most cells, ranging from 4.6- to 27.1-fold after a 4-Gy treatment. No induction occurred for lentiviral vector, lipofection, or naked plasmid exposure. Preincubation of cells with adenovirus failed to show an increase, suggesting that radiation might mediate adenoviral infection by inducing viral uptake into cells. We demonstrated that radiation induced internalization of a fluorescence-labeled adenovirus (Cy3-Ad) and an increase in intracellular viral DNA content. Rats bearing intrahepatic colon carcinoma xenografts were irradiated in the tumor region followed by portal venous administration of an adenoviral vector containing a CMV-beta-galactosidase (beta-gal) gene. Radiation increased beta-gal activity in tumors as much as 5.4-fold after a 25-Gy treatment. These data suggest that a combination of regional radiation treatment with adenovirus gene therapy is a rational strategy for improving adenoviral targeting and transgene expression in tumors.

Dosimetric analysis and comparison of three-dimensional conformal radiotherapy and intensity-modulated radiation therapy for patients with hepatocellular carcinoma and radiation-induced liver disease

PURPOSE

This study compares the difference in dose-volume data between three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) for patients with hepatocellular carcinoma (HCC) and previously documented radiation-induced liver disease (RILD) after 3D-CRT.

MATERIALS AND METHODS

Between November 1993 and December 1999, 68 patients with HCC were treated with 3D-CRT at our institution. Twelve of them were diagnosed with RILD within 4 months of completion of 3D-CRT. RILD was defined as either anicteric elevation of alkaline phosphatase level of at least twofold and nonmalignant ascites, or elevated transaminases of at least fivefold the upper limit of normal or of pretreatment levels. Three-dimensional treatment planning using dose-volume histograms of normal liver was used to obtain the dose-volume data. These 12 patients with RILD were replanned with an IMRT planning system using the five-field (gantry angles 0 degrees, 72 degrees, 144 degrees, 216 degrees, and 288 degrees ) step-and-shoot technique to compare the dosimetric difference in targets and organs at risk between 3D-CRT and IMRT. Mean dose and normal tissue complication probability with literature-cited volume effect parameter of 0.32, curve steepness parameter of 0.15, and TD(50)(1) of 40 Gy, were used for the liver, whereas volume fraction at a given dose level was used for other critical structures. Paired Student t-test with 2-tailed p < 0.05 was used to assess the statistical difference between the two techniques.

RESULTS

With comparable target coverage between 3D-CRT and five-field step-and-shoot IMRT, IMRT was able to obtain a large dose reduction in the spinal cord (5.7% vs. 33.2%, p = 0.007), and achieved at least similar organ sparing for kidneys and stomach. IMRT had diverse dosimetric effect on liver, with significant reduction in normal tissue complication probability (23.7% vs. 36.6%, p = 0.009), but significant increase in mean dose (2924 cGy vs. 2504 cGy, p = 0.009), as compared with 3D-CRT.

CONCLUSIONS

IMRT is capable of preserving acceptable target coverage and improving or at least maintaining the nonhepatic organ sparing for patients with HCC and previously diagnosed RILD after 3D-CRT. The true impact of this technique on the liver remains unsettled and may depend on the exact volume effect of this organ.

Respiratory gating for liver tumors: use in dose escalation

PURPOSE

To determine the clinical impact of the Varian Real-Time Position Monitor (RPM) respiratory gating system for treatment of liver tumors.

METHODS AND MATERIALS

Ten patients with liver tumors were selected for evaluation of this passive system, which tracks motion of reflective markers mounted on the abdomen with an infrared-sensitive camera. At simulation, a fluoroscopic movie, breathing trace, and CT scans synchronized at end-expiration (E-E) and end-inspiration were acquired in treatment position using the RPM system. Organs and gross tumor volume were contoured on each CT. Each organ's positional change between two scan sets was quantified by calculation of the center of volume shift and an "index coefficient," defined as the volume common to the two versions of the organ to the volume included in at least one (intersection/union). Treatment dose was determined by use of normal tissue complication probability calculations and dose-volume histograms. Gated portal images were obtained to monitor gating reproducibility with treatment.

RESULTS

Eight patients received 177 treatments with RPM gating. Average superior-to-inferior (SI) diaphragm motion on initial fluoroscopy was reduced from 22.7 mm without gating to 5.1 mm with gating. Comparing end-inspiration to E-E CT scans, average SI movement of the right diaphragm was 11.5 mm vs. 2.2 mm for two E-E CT scans. For all organs, average E-I SI organ motion was 12.8 mm vs. 2.0 mm for E-E studies. Index coefficients were closer to 1.0 for E-E than end-inspiration scans, indicating gating reproducibility. The average SI displacement of diaphragm apex on gated portal images compared with DRR was 2.3 mm. Treatment was prolonged less than 10 minutes with gating. The reproducible decrease in organ motion with gating enabled reduction in gross tumor volume-to-planning target volume margin from 2 to 1 cm. This allowed for calculated dose increases of 7%-27% (median: 21.3%) in 6 patients and enabled treatment in 2.

CONCLUSION

Gating of radiotherapy for liver tumors enables safe margin reduction on tumor volume, which, in turn, may allow for dose escalation.

Clinical results and prognostic factors in radiotherapy for unresectable hepatocellular carcinoma: a retrospective study of 158 patients

PURPOSE

To analyze the treatment results and prognostic factors affecting survival in patients with unresectable hepatocellular carcinoma treated with local radiotherapy (RT).

METHODS AND MATERIALS

Between 1992 and 2000, 158 patients with unresectable hepatocellular carcinoma received local RT. Sixty-seven patients had an advanced UICC Stage III lesion and 91 patients had Stage IVA. The mean tumor size was 9.0 +/- 3.0 cm, and liver cirrhosis was present in 142 patients. Local RT was combined with transarterial chemoembolization as primary treatment (107 patients) or as salvage after failure of repeated transarterial chemoembolization (51 patients). The mean radiation dose was 48.2 +/- 7.9 Gy in daily 1.8-Gy fractions.

RESULTS

The mean follow-up was 21.6 months after diagnosis and 14.6 months after RT. The response rate was 67.1%. The overall survival rate at 2 and 5 years was 30.5% and 9%, respectively, from the time of diagnosis (median survival time 16 months) and 19.9% and 4.7%, respectively, after RT (median survival time 10 months). On univariate analysis, tumor size (p = 0.047), the presence of portal vein thrombosis (p = 0.007), and RT dose (p = 0.001) were significant factors for survival. However, on multivariate analysis, RT dose was the only significant factor (p = 0.01).

CONCLUSION

Local RT achieved substantial tumor regression and survival. The radiation dose was found to be a significant prognostic factor in the RT of hepatocellular carcinoma. Additional efforts for dose escalation are warranted to improve the treatment results in parallel with better protecting the nontumorous liver.

A novel strategy for in vivo expansion of transplanted hepatocytes using preparative hepatic irradiation and FasL-induced hepatocellular apoptosis

A strategy for inducing preferential proliferation of the engrafted hepatocytes over host liver cells should markedly increase the benefit of hepatocyte transplantation for the treatment of liver diseases and ex vivo gene therapy. We hypothesized that preparative hepatic irradiation (HIR) to inhibit host hepatocellular regeneration in combination with the mitotic stimulus of host hepatocellular apoptosis should permit repopulation of the liver by transplanted cells. To test this hypothesis, congeneic normal rat hepatocytes were transplanted into UDP-glucuronosyltransferase (UGT1A1)-deficient jaundiced Gunn rats (a model of Crigler-Najjar syndrome type I), following HIR and adenovirus-mediated FasL gene transfer. Progressive repopulation of the liver by engrafted UGT1A1-proficient hepatocytes over 5 months was demonstrated by the appearance of UGT1A1 protein and enzyme activity in the liver, biliary bilirubin glucuronides secretion, and long-term normalization of serum bilirubin levels. This is the first demonstration of massive hepatic repopulation by transplanted cells by HIR and FasL-induced controlled apoptosis of host liver cells.

Palliative and postoperative radiotherapy in biliary tract cancer

Local failure is the primary limitation for cure in patients with BTC. whether or not they have been resected. The use of radiotherapy with or without chemotherapy in the postoperative setting is controversial, but some studies have reported improvement in 5-year survival. In patients with unresectable BTC, EBRT offers effective palliation of symptomatic disease and has resulted in improved median and long-term survival in a small number of patients in most studies. Novel approaches, including neoadjuvant chemoradiotherapy combined with OLT, and escalated conformal irradiation, seem to be promising and warrant further investigation.

Radiation-induced liver disease after three-dimensional conformal radiotherapy for patients with hepatocellular carcinoma: dosimetric analysis and implication

PURPOSE

To analyze the correlation of radiation-induced liver disease (RILD) with patient-related and treatment-related dose-volume factors and to describe the probability of RILD by a normal tissue complication probability (NTCP) model for patients with hepatocellular carcinoma (HCC) treated with three-dimensional conformal radiotherapy (3D-CRT).

METHODS AND MATERIALS

Between November 1993 and December 1999, 93 patients with intrahepatic malignancies were treated with 3D-CRT at our institution. Sixty-eight patients who were diagnosed with HCC and had complete 3D dose-volume data were included in this study. Of the 68 patients, 50 had chronic viral hepatitis before treatment, either type B or type C. According to the Child-Pugh classification for liver cirrhosis, 53 patients were in class A and 15 in class B. Fifty-two patients underwent transcatheter arterial chemoembolization with an interval of at least 1 month between transcatheter arterial chemoembolization and 3D-CRT to allow adequate recovery of hepatic function. The mean dose of radiation to the isocenter was 50.2 +/- 5.9 Gy, in daily fractions of 1.8-2Gy. No patient received whole liver irradiation. RILD was defined as Grade 3 or 4 hepatic toxicity according to the Common Toxicity Criteria of the National Cancer Institute. All patients were evaluated for RILD within 4 months of RT completion. Three-dimensional treatment planning with dose-volume histogram analysis of the normal liver was used to compare the dosimetric difference between patients with and without RILD. Maximal likelihood analysis was conducted to obtain the best estimates of parameters of the Lyman NTCP model. Confidence intervals of the fitted parameters were estimated by the profile likelihood method.

RESULTS

Twelve of the 68 patients developed RILD after 3D-CRT. None of the patient-related variables were significantly associated with RILD. No difference was found in tumor volume (780 cm(3) vs. 737 cm(3), p = 0.86), normal liver volume (1210 cm(3) vs. 1153 cm(3), p = 0.64), percentage of normal liver volume with radiation dose >30 Gy (V(30 Gy); 42% vs. 33%, p = 0.05), and percentage of normal liver volume with >50% of the isocenter dose (V(50%); 45% vs. 36%, p = 0.06) between patients with and without RILD. The mean hepatic dose was significantly higher in patients with RILD (2504 cGy vs. 1965 cGy, p = 0.02). The probability of RILD in patients could be expressed as follows: probability = 1/[1 + exp(-(0.12 x mean dose - 4.29))], with coefficients significantly different from 0. The best estimates of the parameters in the Lyman NTCP model were the volume effect parameter of 0.40, curve steepness parameter of 0.26, and 50% tolerance dose for uniform irradiation of whole liver [TD(50)(1)] of 43 Gy. Patients with RILD had a significantly higher NTCP than did those with no RILD (26.2% vs. 15.8%; p = 0.006), using the best-estimated parameters.

CONCLUSION

Dose-volume histogram analysis can be effectively used to quantify the tolerance of the liver to RT. Patients with RILD had received a significantly higher mean dose to the liver and a significantly higher NTCP. The fitted volume effect parameter of the Lyman NTCP model was close to that from the literature, but much lower in our patients with HCC and prevalent chronic viral hepatitis than that reported in other series with patients with normal liver function. Additional efforts should be made to test other models to describe the radiation tolerance of the liver for Asian patients with HCC and preexisting compromised hepatic reserve.

Dose-response relationship in local radiotherapy for hepatocellular carcinoma

PURPOSE

Dose escalation using three-dimensional conformal radiotherapy (3D-CRT) is based on the hypothesis that increasing the dose can enhance tumor control. This study aimed to determine whether a dose-response relationship exists in local radiotherapy for primary hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

One hundred fifty-eight patients were enrolled in the present study between January 1992 and March 2000. The exclusion criteria included the presence of an extrahepatic metastasis, liver cirrhosis of Child class C, tumors occupying more than two-thirds of the entire liver, and a performance status on the Eastern Cooperative Oncology Group scale of more than 3. Radiotherapy was given to the field, including the tumor, with generous margin using 6- or 10-MV X-rays. The mean radiation dose was 48.2 +/- 7.9 Gy in daily 1.8-Gy fractions. The tumor response was assessed based on diagnostic radiologic examinations, including a computed tomography scan, magnetic resonance imaging, and hepatic artery angiography 4-8 weeks after the completion of treatment. Liver toxicity and gastrointestinal complications were evaluated.

RESULTS

An objective response was observed in 106 of 158 (67.1%) patients. Statistical analysis revealed that the total dose was the most significant factor associated with the tumor response. The response rates in patients treated with doses <40 Gy, 40-50 Gy, and >50 Gy were 29.2%, 68.6%, and 77.1%, respectively. Survivals at 1 and 2 years after radiotherapy were 41.8% and 19.9%, respectively, with a median survival time of 10 months. The rate of liver toxicity according to the doses <40 Gy, 40-50 Gy, and >50 Gy was 4.2%, 5.9%, and 8.4%, respectively, and the rate of gastrointestinal complications was 4.2%, 9.9%, and 13.2%, respectively.

CONCLUSIONS

The present study showed the existence of a dose-response relationship in local radiotherapy for primary HCC. Only the radiation dose was a significant factor for predicting an objective response. The results of this study showed that 3D-CRT can theoretically be used for treating primary HCC.

Methodological issues in radiation dose-volume outcome analyses: summary of a joint AAPM/NIH workshop

This report represents a summary of presentations at a joint workshop of the National Institutes of Health and the American Association of Physicists in Medicine (AAPM). Current methodological issues in dose-volume modeling are addressed here from several different perspectives. Areas of emphasis include (a) basic modeling issues including the equivalent uniform dose framework and the bootstrap method, (b) issues in the valid use of statistics, including the need for meta-analysis, (c) issues in dealing with organ deformation and its effects on treatment response, (d) evidence for volume effects for rectal complications, (e) the use of volume effect data in liver and lung as a basis for dose escalation studies, and (f) implications of uncertainties in volume effect knowledge on optimized treatment planning. Taken together, these approaches to studying volume effects describe many implications for the development and use of this information in radiation oncology practice. Areas of significant interest for further research include the meta-analysis of clinical data; interinstitutional pooled data analyses of volume effects; analyses of the uncertainties in outcome prediction models, minimal parameter number outcome models for ranking treatment plans (e.g., equivalent uniform dose); incorporation of the effect of motion in the outcome prediction; dose-escalation/isorisk protocols based on outcome models; the use of functional imaging to study radioresponse; and the need for further small animal tumor control probability/normal tissue complication probability studies.

Analysis of radiation-induced liver disease using the Lyman NTCP model

PURPOSE

To describe the dose-volume tolerance for radiation-induced liver disease (RILD) using the Lyman-Kutcher-Burman (LKB) normal tissue complication probability (NTCP) model.

METHODS AND MATERIALS

A total of 203 patients treated with conformal liver radiotherapy and concurrent hepatic arterial chemotherapy were prospectively followed for RILD. Normal liver dose-volume histograms and RILD status for these patients were used as input data for determination of LKB model parameters. A complication was defined as Radiation Therapy Oncology Group Grade 3 or higher RILD < o r =4 months after completion of radiotherapy. A maximal likelihood analysis yielded best estimates for the LKB NTCP model parameters for the liver for the entire patient population. A multivariate analysis of the potential factors associated with RILD was also completed, and refined LKB model parameters were obtained for patient subgroups with different risks of RILD.

RESULTS

Of 203 patients treated with focal liver irradiation, 19 developed RILD. The LKB NTCP model fit the complication data for the entire group. The "n" parameter was larger than previously described, suggesting a strong volume effect for RILD and a correlation of NTCP with the mean liver dose. No cases of RILD were observed when the mean liver dose was <31 Gy. Multivariate analysis demonstrated that in addition to NTCP and the mean liver dose, a primary hepatobiliary cancer diagnosis (vs. liver metastases), bromodeoxyuridine hepatic artery chemotherapy (vs. fluorodeoxyuridine chemotherapy), and male gender were associated with RILD. For 169 patients treated with fluorodeoxyuridine, the refined LKB model parameters were n = 0.97, m = 0.12, tolerance dose for 50% complication risk for whole organ irradiated uniformly [TD50(1)] = 45.8 Gy for patients with liver metastases, and TD50(1) = 39.8 Gy for patients with primary hepatobiliary cancer.

CONCLUSION

These data demonstrate that the liver exhibits a large volume effect for RILD, suggesting that the mean liver dose may be useful in ranking radiation plans. The inclusion of clinical factors, especially the diagnosis of primary hepatobiliary cancer vs. liver metastases, improves the estimation of NTCP over that obtained solely by the use of dose-volume data. These findings should facilitate the application of focal liver irradiation in future clinical trials.

Limitations of conventional doses of chemoradiation for unresectable biliary cancer

PURPOSE

To determine, in a retrospective review, the limitations of definitive chemoradiation in the treatment of patients with unresectable extrahepatic cholangiocarcinoma and generate testable hypotheses for future prospective clinical trials.

METHODS AND MATERIALS

Between 1957 and 2000, 52 patients with localized, unresectable cholangiocarcinoma were treated with radiotherapy (RT) with or without concurrent chemotherapy. Unresectable disease was defined, by evidence on imaging studies or at surgical exploration, as localized tumor abutting or involving the main portal vein, tumor involvement of secondary biliary radicals, or evidence of nodal metastases. Patients were grouped according to the RT dose: 27 patients received a total dose of 30 Gy (Group 1), 14 patients received 36-50.4 Gy (Group 2), and 11 patients received 54-85 Gy (Group 3). 192Ir intracavitary boosts (median 20 Gy) were delivered in 3 patients, and an intraoperative boost (20 Gy) was used in 1 patient. Of the 52 patients, 38 (73%) received concomitant protracted venous infusion of 5-fluorouracil (200-300 mg/m2 daily, Monday through Friday). Kaplan-Meier analysis was used to calculate the actuarial 1-year and median overall survival (OS), radiographic local progression, symptomatic progression, and distant failure. Treatment-related variables and prognostic factors were evaluated using the log-rank test.

RESULTS

The first site of disease progression was local in 72% of cases. The actuarial local progression rate at 12 months for all patients was 59%. The median time to radiographic local progression was 9, 11, and 15 months in Groups 1, 2, and 3, respectively (p = 0.48). Fifteen percent of all patients developed metastatic disease (1-year OS rate 18%). The median survival rate for all patients was 10 months (1-year OS rate 44%). The RT dose, use of concurrent chemotherapy, histologic grade, initial extent of liver involvement, and extent of vascular involvement had no influence on radiographic local progression or OS. Grade 3 or greater toxicity was similar in all dose groups (22% vs. 14% vs. 27%, p = 0.718).

CONCLUSION

The primary limitation of definitive chemoradiation was local progression. Although the small patient numbers limited the statistical power of this study, a suggestion of improved local control was found with the use of higher RT doses. To address this pattern of failure, future prospective investigation using high-dose conformal RT with novel cytotoxic and/or biologic agents with radiosensitizing properties is warranted.

The effect of therapeutic irradiation on LactoSorb absorbable copolymer

Bioabsorbable implants continue to gain popularity in providing temporary internal fixation due to their many advantages over metallic internal fixation. Coincident with the presence of internal fixation devices, it may be necessary to use radiotherapy to treat tumors. While metal implants can alter the distribution of the radiotherapy beam, bioabsorbable polymer implants are, essentially, tissue equivalent. This ionizing irradiation, in sufficiently high dose, can affect polymers through chain scission and cross-linking and accelerate the hydrolysis of absorbable polymers. However, little is known about the effects of therapeutic doses on such materials. This study exposed LactoSorb (Biomet, Inc., Warsaw, IN) absorbable copolymer to doses of x-ray irradiation in a clinically relevant manner, in vitro, with individual doses of 2 Gy administered five days per week for up to eight weeks, yielding a total cumulative dose of up to 80 Gy. Specimens were tested both mechanically and for inherent viscosity. Overall, the LactoSorb specimens withstood exposure to the irradiation exceedingly well, providing empirical evidence of the suitability of this material for temporary internal fixation when subsequent radiotherapy in the region is probable.