Proton Beam Therapy for Aged Patients With Hepatocellular Carcinoma

Proton Beam Therapy and Photon-Based Magnetic Resonance Image-Guided Radiation Therapy: The Next Frontiers of Radiation Therapy for Hepatocellular Carcinoma

External beam radiation therapy (EBRT) has increasingly been utilized in the treatment of hepatocellular carcinoma (HCC) due to technological advances with positive clinical outcomes. Innovations in EBRT include improved image guidance, motion management, treatment planning, and highly conformal techniques such as intensity-modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT). Moreover, proton beam therapy (PBT) and magnetic resonance image-guided radiation therapy (MRgRT) have expanded the capabilities of EBRT. PBT offers the advantage of minimizing low- and moderate-dose radiation to the surrounding normal tissue, thereby preserving uninvolved liver and allowing for dose escalation. MRgRT provides the advantage of improved soft tissue delineation compared to computerized tomography (CT) guidance. Additionally, MRgRT with online adaptive therapy is particularly useful for addressing motion not otherwise managed and reducing high-dose radiation to the normal tissue such as the stomach and bowel. PBT and online adaptive MRgRT are emerging technological advancements in EBRT that may provide a significant clinical benefit for patients with HCC.

Proton therapy in the treatment of hepatocellular carcinoma

Liver cancer represents one of the most common causes of death from cancer worldwide. Hepatocellular carcinoma (HCC) accounts for 90% of all primary liver cancers. Among local therapies, evidence regarding the use of radiation therapy is growing. Proton therapy currently represents the most advanced radiation therapy technique with unique physical properties which fit well with liver irradiation. Here, in this review, we aim to 1) illustrate the rationale for the use of proton therapy (PT) in the treatment of HCC, 2) discuss the technical challenges of advanced PT in this disease, 3) review the major clinical studies regarding the use of PT for HCC, and 4) analyze the potential developments and future directions of PT in this setting.

Proton Therapy in the Management of Hepatocellular Carcinoma

Proton radiation therapy plays a central role in the treatment of hepatocellular carcinoma (HCC). Because of the near-zero exit dose and improved sparing of normal liver parenchyma, protons are being used even in challenging scenarios, including larger or multifocal liver tumors, and those associated with vascular tumor thrombus. There is a mounting level of evidence that suggests that protons are superior to photons in terms of survival and toxicity outcomes, specifically the progression to liver failure. A randomized controlled trial comparing protons to photons is currently underway to verify this hypothesis.

Capacity of proton beams in preserving normal liver tissue during proton beam therapy for hepatocellular carcinoma

Unirradiated liver volume (ULV) preservation rate is an important factor associated with radiation-induced liver disease (RILD) in patients with hepatocellular carcinoma (HCC) undergoing proton beam therapy (PBT). The purpose of this study is to identify the predictors for ULV preservation and quantify the capacity of proton beams in normal liver sparing during PBT. We reviewed planning data of 92 patients with single intrahepatic HCC tumors undergoing PBT. The potential clinical and planning factors that may affect ULV preservation were involved in multiple linear regression for ULV preservation rate. The significant factors were determined to be predictors and their influences were quantified. The median ULV preservation rate was 62.08%. All the assessed clinical factors showed significant effects on ULV preservation rate: clinical target volume (CTV), P < 0.001; portal vein tumor thrombosis (PVTT), P = 0.010; left lobe tumor, P = 0.010. In contrast, none of the planning factors demonstrated significance. The coefficients of significant factors in multiple linear regression were 60.85 for intercept, -0.02 for CTV, -9.01 for PVTT and 8.31 for left lobe tumors. The capacity of proton beams to spare normal liver tissue during PBT for HCC is mainly affected by clinical factors. The baseline of the ULV preservation rate is 60.85%, decreasing 0.02% with each milliliter of CTV increase and 9.01% for tumors with PVTT, and increasing 8.31% for tumors limited to the left lobe. Further clinical studies should be carried out to correlate our dosimetric findings with clinical outcomes.

External beam radiation therapy in a centenarian with primary liver cancer: A case report

RATIONALE

Due to unprecedented global aging, the number of elderly and super-elderly patients with cancer is increasing. However, restricted by comorbidities or fragility, many elderly patients are considered ineligible to receive invasive therapies. A centenarian with primary liver cancer (PLC) was treated by external beam radiation therapy (EBRT). This rare case deserves our attention.

PATIENT CONCERNS

We present a rare case of a centenarian with PLC. The super-elderly male patient complained that 2 liver lesions were found by abdominal ultrasonography in June 2016.

DIAGNOSES

The Segment 7 (S7) lesion and the Segment 5/8 (S5/8) lesion were clinically diagnosed as PLC successively.

INTERVENTIONS

The S7 lesion was considered PLC initially and treated by EBRT in October 2016. In the 1-year follow-up after EBRT, the S7 lesion was well controlled. Unfortunately, the S5/8 lesion had increased in size, was diagnosed as PLC and subsequently treated by CyberKnife in another hospital. However, local failure of the S5/8 lesion was suggested 15 months after CyberKnife. At the age of 102 years, the patient received re-irradiation for the S5/8 lesion.

OUTCOMES

Three months after re-irradiation, des-γ-carboxy-prothrombin decreased to normal; no significant change in the S5/8 lesion was found in Magnetic Resonance Imaging. No severe acute or late toxicities were reported after each course of EBRT. Unfortunately, the patient died of respiratory failure caused by severe pneumonia in mid-March 2020.

CONCLUSION

Advanced age is not a contraindication for elderly patients with cancer to receive radiotherapy and even re-irradiation.

Transitions of Liver and Biliary Enzymes during Proton Beam Therapy for Hepatocellular Carcinoma

Proton beam therapy (PBT) is a curative treatment for hepatocellular carcinoma (HCC), because it can preserve liver function due to dose targeting via the Bragg peak. However, the degree of direct liver damage by PBT is unclear. In this study, we retrospectively analyzed liver/biliary enzymes and total bilirubin (T-Bil) as markers of direct liver damage during and early after PBT in 300 patients. The levels of these enzymes and bilirubin were almost stable throughout the treatment period. In patients with normal pretreatment levels, aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), and T-Bil were abnormally elevated in only 2 (1.2%), 1 (0.4%), 0, 2 (1.2%), and 8 (3.5%) patients, respectively, and in 8 of these 13 patients (61.5%) the elevations were temporary. In patients with abnormal pretreatment levels, the levels tended to decrease during PBT. GGT and T-Bil were elevated by 1.62 and 1.57 times in patients who received 66 Gy (RBE) in 10 fractions and 74 Gy (RBE) in 37 fractions, respectively, but again these changes were temporary. These results suggest that direct damage to normal liver caused by PBT is minimal, even if a patient has abnormal pretreatment enzyme levels.

Proton beam therapy for liver cancers

Proton beam therapy (PBT) delivers less dose to nearby normal organs compared to X-ray therapy (XRT), which is particularly relevant for treating liver cancers given that both mean and low liver dose are among the most significant predictors of radiation induced liver disease (RILD). High-dose PBT has been shown to achieve excellent long-term tumor control with minimal toxicity in hepatocellular carcinoma (HCC) patients. Increasing data support ablative PBT for patients with unresectable cholangiocarcinoma or liver metastases, especially those with larger tumors not suitable for XRT.

Impact of Proton Beam Irradiation of an Anatomic Subsegment of the Liver for Hepatocellular Carcinoma

PURPOSE

The objective of this research was to elucidate the impact on the prognosis, including the survival prognosis, resulting from proton beam irradiation of an anatomic subsegment of the liver (ASPT) for the treatment of hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

A total of 110 patients who received a diagnosis of HCC were analyzed in this retrospective study. Definitive proton beam therapy was delivered at a dose of 76 Gy (relative biological effectiveness) in 20 fractions between January 2008 and December 2015. When the HCC widely abutted blood vessels or when multiple HCC tumors occurred within the same liver subsegment, the clinical target volume was outlined as an anatomic subsegment of the liver, according to the portal territory, containing the tumor. In the remaining cases, the clinical target volume was delineated by adding a 5-mm margin around the gross tumor volume. The overall survival (OS), progression-free survival (PFS), and local control rates and adverse events were assessed. A review of the medical charts assessed adverse events that occurred during and after the treatment and were classified according to the Common Terminology Criteria for Adverse Events version 4.0.

RESULTS

The median follow-up duration was 36.5 months (range, 1-90.6 months). The median age of the patients was 73 years (range, 48-90 years). ASPT was performed in 31 patients (28%). Three-year OS, PFS, and local control rates were 74.2%, 40.4%, and 91.7%, respectively. Multivariate analysis identified ASPT as a factor that significantly improved PFS (P = .049) but not OS (P = .79). No association was found between ASPT and the frequency of grade ≥3 acute/late adverse events.

CONCLUSIONS

ASPT was associated with a reduction in the rate of tumor progression and no significant toxicity but was not associated with OS.

Proton Beam Therapy and Carbon Ion Radiotherapy for Hepatocellular Carcinoma

Charged particle therapy with proton beam therapy (PBT) and carbon ion radiotherapy (CIRT) has emerged as a promising radiation modality to minimize radiation hepatotoxicity while maintaining high rates of tumor local control. Both PBT and CIRT deposit the majority of their dose at the Bragg peak with little to no exit dose, resulting in superior sparing of normal liver tissue. CIRT has an additional biological advantage of increased relative biological effectiveness, which may allow for increased hypofractionation regimens. Retrospective and prospective studies have demonstrated encouragingly high rates of local control and overall survival and low rates of hepatotoxicity with PBT and CIRT. Ongoing randomized trials will evaluate the value of PBT over photons and other standard liver-directed therapies and future randomized trials are needed to assess the value of CIRT over PBT.

A validated proton beam therapy patch-field protocol for effective treatment of large hepatocellular carcinoma

Development of a curative local treatment for large hepatocellular carcinoma (HCC) is an important issue. Here, we investigated the dose homogeneity, safety and antitumor effectiveness of proton beam therapy (PBT) using a patch-field technique for large HCC. Data from nine patients (aged 52-79 years) with large HCC treated with patch-field PBT were investigated. The cranial-caudal diameters of the clinical target volumes (CTVs) were 15.0-18.6 cm (median 15.9). The CTV was divided cranially and caudally while both isocenters were aligned along the cranial-caudal axis and overlap of the cranial and caudal irradiation fields was set at 0-0.5 mm. Multileaf collimators were used to eliminate hot or cold spots. Total irradiation doses were 60-76.4 Gy equivalents. Irradiation doses as a percentage of the prescription dose (from the treatment planning system) around the junction were a minimum of 93-105%, a mean of 99-112%, and a maximum of 105-120%. Quality assurance (QA) was assessed in the cranial and caudal irradiation fields using imaging plates. Acute adverse effects of Grade 3 were observed in one patient (hypoalbuminemia), and a late adverse effect of Grade 3 was observed in one patient (liver abscess). Child-Pugh class elevations were observed in four patients (A to B: 3; B to C: 1). Overall survival rates at 1 and 2 years were 55 and 14%, respectively, with a median overall survival of 13.6 months. No patients showed local recurrence. Patch-field PBT supported by substantial QA therefore is one of the treatment options for large HCC.

Strategic application of radiotherapy for hepatocellular carcinoma

With increasing clinical use, radiotherapy (RT) has been considered reliable and effective method for hepatocellular carcinoma (HCC) treatment, depending on extent of disease and patient characteristics. RT for HCC can improve therapeutic outcomes through excellent local control, downstaging, conversion from unresectable to resectable status, and treatments of unresectable HCCs with vessel invasion or multiple intrahepatic metastases. In addition, further development of modern RT technologies, including image-guided radiotherapy (IGRT), intensity-modulated radiotherapy (IMRT), and stereotactic body radiotherapy, has expanded the indication of RT. An essential feature of IGRT is that it allows image guidance therapy through in-room images obtained during radiation delivery. Compared with 3D-conformal RT, distinctions of IMRT are inverse treatment planning process and use of a large number of treatment fields or subfields, which provide high precision and exquisitely conformal dose distribution. These modern RT techniques allow more precise treatment by reducing inter- and intra-fractional errors resulting from daily changes and irradiated dose at surrounding normal tissues. More recently, particle therapy has been actively investigated to improve effectiveness of RT. This review discusses modern RT strategies for HCC, as well as optimal selection of RT in multimodal approach for HCC.

Carbon ion radiotherapy for 80 years or older patients with hepatocellular carcinoma

BACKGROUND

To evaluate the safety and efficacy of carbon ion radiotherapy (C-ion RT) for 80 years or older patients with hepatocellular carcinoma (HCC).

METHODS

Eligibility criteria of this retrospective study were: 1) HCC confirmed by histology or typical hallmarks of HCC by imaging techniques of four-phase multidetector-row computed tomography or dynamic contrast-enhanced magnetic resonance imaging; 2) no intrahepatic metastasis or distant metastasis; 3) no findings suggesting direct infiltration of the gastrointestinal tract; 4) performance status ≤2 by Eastern Cooperative Oncology Group classification; and 5) Child-Pugh classification A or B. Patients received C-ion RT with 52.8 Gy (RBE) or 60.0 Gy (RBE) in four fractions for usual cases and 60.0 Gy (RBE) in 12 fractions for close-to-gastrointestinal tract cases. Toxicities were classified using the National Cancer Institute's Common Terminology Criteria for Adverse Events (Version 4.0).

RESULTS

Between March 2011 and November 2015, 31 patients were treated. The median follow-up period of all patients was 23.2 months (range: 8.4-55.3 months). Median age at the time of registration of C-ion RT was 83 years (range: 80-95 years). Child-Pugh grade A and B were 27 patients and 4 patients, respectively. The 2-year estimated overall survival, local control, and progression-free survival rates were 82.3%, 89.2%, and 51.3%, respectively. No patients had Grade 2 or higher acute toxicities (within 3 months after C-ion RT). One patient experienced progression in Child-Pugh classification from A to B within 3 months after C-ion RT. In late toxicities, Grade 3 encephalopathy was observed in 3 patients, and 2 improved with medication.

CONCLUSIONS

C-ion RT was effective with minimal toxicities for 80 years or older patients with hepatocellular carcinoma.

TRIAL REGISTRATION

UMIN000020571 : date of registration, 14 January 2016, retrospectively registered.

A systematic review of publications on charged particle therapy for hepatocellular carcinoma

Charged particle therapy (proton beam therapy and carbon ion therapy) is a form of radiotherapy which has the unique characteristic of superior depth dose distribution, and has been used for the treatment of hepatocellular carcinoma (HCC) in a limited number of patients, especially in Japan. We undertook a systematic review to define the clinical utility of charged particle therapy for patients with HCC. We searched the MEDLINE database from 1983 to June 2016 to identify clinical studies on charged particle therapy for HCC. Primary outcomes of interest were local control, overall survival, and late radiation morbidities. A total of 13 cohorts from 11 papers were selected from an initial dataset of 78 papers. They included a randomized controlled trial comparing proton beam therapy with transarterial chemoembolization, 9 phase I or II trials and 2 retrospective studies. The reported actuarial local control rates ranged from 71.4-95% at 3 years, and the overall survival rates ranged from 25-42.3% at 5 years. Late severe radiation morbidities were uncommon, and a total of 18 patients with grade ≥3 late adverse events were reported among the 787 patients included in this analysis. Charged particle therapy for HCC was associated with good local control with limited probability of severe morbidities. The cost-effectiveness and the distinctive clinical advantages of charged particle therapies should be clarified in order to become a socially accepted treatment modality for HCC.

Proton beam therapy for hepatocellular carcinoma

INTRODUCTION

Radiation therapy is an effective treatment option for hepatocellular carcinoma (HCC) patients. However, radiotherapy for HCC still has limited recognition as a standard treatment option in international consensus guidelines due to a paucity of randomized controlled trials and the risk of hepatotoxicity, which is primarily mediated by baseline liver function and dose delivered to non-tumor liver cells. Proton beam therapy (PBT) may offer advantages over photon-based radiation treatments through its dosimetric characteristic of sparing more liver volume at low to moderate doses. PBT has the potential to reduce radiation-related hepatotoxicity and allow for tumor dose escalation. Areas covered: This article reviews the clinical rationale for using PBT for HCC patients and clinical outcome and toxicity data from retrospective and prospective studies. PBT-specific technical challenges for these tumors and appropriate selection of patients to be treated with PBT are discussed. Expert commentary: Local control, overall survival, and toxicity results are promising for liver PBT. Future studies, including ongoing randomized cooperative group trials, will aim to determine the incremental benefit of PBT over photons and which patients are most suitable for PBT.

Effectiveness of proton beam therapy on liver metastases of esophageal cancer: report of a case

A 53-year-old man with multiple liver metastasis of esophageal cancer underwent four courses of chemotherapy. After four courses of chemotherapy, positron emission tomography showed progressive disease. Because it was difficult to control the cancer only by chemotherapy, we performed proton beam therapy (PBT) combined with chemotherapy. The irradiated parts were the primary tumor, liver metastases (S2/S4/S6), and mediastinal lymph nodes. The primary tumor including the mediastinal lymph nodes and the S2/S4/S6 metastases received proton beam irradiation at a total dose of 68.2 Gy in 31 fractions and 66.0 Gy in 30 fractions, respectively, according to tumor location. This resulted in a complete response as shown by positron emission tomography. In our experience, PBT exerted a curative effect on liver metastases of esophageal cancer. It is thought that PBT may be effective in the treatment of esophageal cancer. This is the first report about PBT for liver metastases of esophageal cancer.

Clinical outcomes and toxicities of proton radiotherapy for gastrointestinal neoplasms: a systematic review

BACKGROUND

Proton beam radiotherapy (PBT) is frequently shown to be dosimetrically superior to photon radiotherapy (RT), though supporting data for clinical benefit are severely limited. Because of the potential for toxicity reduction in gastrointestinal (GI) malignancies, we systematically reviewed the literature on clinical outcomes (survival/toxicity) of PBT.

METHODS

A systematic search of PubMed, EMBASE, abstracts from meetings of the American Society for Radiation Oncology, Particle Therapy Co-Operative Group, and American Society of Clinical Oncology was conducted for publications from 2000-2015. Thirty-eight original investigations were analyzed.

RESULTS

Although results of PBT are not directly comparable to historical data, outcomes roughly mirror previous data, generally with reduced toxicities for PBT in some neoplasms. For esophageal cancer, PBT is associated with reduced toxicities, postoperative complications, and hospital stay as compared to photon radiation, while achieving comparable local control (LC) and overall survival (OS). In pancreatic cancer, numerical survival for resected/unresected cases is also similar to existing photon data, whereas grade ≥3 nausea/emesis and post-operative complications are numerically lower than those reported with photon RT. The strongest data in support of PBT for HCC comes from phase II trials demonstrating very low toxicities, and a phase III trial of PBT versus transarterial chemoembolization demonstrating trends towards improved LC and progression-free survival (PFS) with PBT, along with fewer post-treatment hospitalizations. Survival and toxicity data for cholangiocarcinoma, liver metastases, and retroperitoneal sarcoma are also roughly equivalent to historical photon controls. There are two small reports for gastric cancer and three for anorectal cancer; these are not addressed further.

CONCLUSIONS

Limited quality (and quantity) of data hamper direct comparisons and conclusions. However, the available data, despite the inherent caveats and limitations, suggest that PBT offers the potential to achieve significant reduction in treatment-related toxicities without compromising survival or LC for multiple GI malignancies. Several randomized comparative trials are underway that will provide more definitive answers.

Proton beam therapy in Japan: current and future status

The number of patients treated by proton beam therapy in Japan since 2000 has increased; in 2016, 11 proton facilities were available to treat patients. Notably, proton beam therapy is very useful for pediatric cancer; since the pediatric radiation dose to normal tissues should be reduced as much as possible because of the effect of radiation on growth, intellectual development, endocrine organ function and secondary cancer development. Hepatocellular carcinoma is common in Asia, and most of the studies of proton beam therapy for liver cancer have been reported by Japanese investigators. Proton beam therapy is also a standard treatment for nasal and paranasal lesions and lesions at the base of the skull, because the radiation dose to critical organs such as the eyes, optic nerves and central nervous system can be reduced with proton beam therapy. For prostate cancer, comparative studies that address adverse effects, safety, patient quality of life and socioeconomic issues should be performed to determine the appropriate use of proton beam therapy for prostate cancer. Regarding new proton beam therapy applications, experience with proton beam therapy combined with chemotherapy is limited, although favorable outcomes have been recently reported for locally advanced lung cancer, esophageal cancer and pancreatic cancer. Therefore, 'chemoproton' therapy appears to be a very attractive field for further clinical investigations. In conclusion, there are cost issues and considerations regarding national insurance for the use of proton beam therapy in Japan. Further studies and discussions are needed to address the use of proton beam therapy for several types of cancers, and for maintaining the quality of life of patients while retaining a high cure rate.

Proton Beam Therapy for Hepatocellular Carcinoma: A Review of the University of Tsukuba Experience

Hepatocellular carcinoma (HCC) is the second most common cause of cancer-related death worldwide. Many treatment modalities were developed for HCC, including surgical resection, percutaneous ethanol injection, radiofrequency ablation, transarterial chemoembolization, liver transplantation, and sorafenib therapy. Our institution has shown that proton beam therapy (PBT) is also a safe, effective, and feasible treatment modality for HCC. The University of Tsukuba began to use PBT for HCC in 1983, and we have reported many findings during the past 3 decades. In this review, we will describe the history of PBT, our experience of using PBT for HCC, and its application based on tumor location, thrombosis, tumor size, and liver function.

Hepatic resection of hepatocellular carcinoma after proton beam therapy: A case report

Despite the widespread use of proton beam therapy (PBT) as locoregional therapy, there is currently a lack of histological evidence about the therapeutic effect of PBT for hepatocellular carcinoma (HCC). We present a case of hepatectomy and histological examination of HCC initially treated by PBT. A 76-year-old man with chronic hepatitis C underwent routine ultrasound surveillance, which revealed a 22-mm HCC in segment 4 of the liver. His hepatic reserve was adequate for surgical resection of the tumor; however, he chose to undergo PBT because of his cardiac disease. The patient received 66 Gy in 10 fractions with no toxicity exceeding grade 1. Six months after completion of PBT, contrast computed tomography showed that the tumor had increased in size to 27 mm, and the marginal part of the tumor, but not the central region, was enhanced. Additionally, two new hypervascular nodules were present in segments 5 and 6. The patient underwent surgical treatment 7 months after PBT. The operation and postoperative clinical course were uneventful. Nine months later, however, computed tomography demonstrated new, small, enhanced nodules in the remnant liver (segments 3, 5 and 6) and sacrum. In conclusion, PBT is a valuable treatment for HCC; however, it is difficult to evaluate therapeutic effect of HCC during the early post-irradiation period and provide an alternative treatment if PBT is not effective, especially in HCC cases with good liver function.

Proton beam therapy for unresectable intrahepatic cholangiocarcinoma

BACKGROUND AND AIM

Treatment for unresectable intrahepatic cholangiocarcinoma (ICC) has not been established. The aim of the study was to evaluate the outcome of proton beam therapy (PBT) for patients with unresectable ICC.

METHODS

Up to 2010, 20 patients (11 males, 9 females, median age 63 years old) with unresectable ICC (two, seven, seven, and four in stages II, IIIA, IIIC, and IV, respectively) were treated with PBT. The largest dimensions of the tumors ranged from 15 to 140 mm (median: 50 mm). The intrahepatic region and lymph nodes received median total proton doses of 72.6 GyE in 22 fractions and 56.1 GyE in 17 fractions, respectively. Four patients received concurrent chemotherapy (tegafur, gimeracil, and oteracil; TS-1) during PBT. Twelve patients were treated curatively, and eight were treated palliatively because tumors were present outside the irradiation field.

RESULTS

In the curative group, nine tumors within the irradiated field were controlled in follow-up of 8.6-62.6 months (median: 20.8 months). Median survival rates in the curative and palliative groups were 27.5 and 9.6 months, respectively, and overall 1- and 3-year survival rates were 82% and 38%, and 50% and 0%, respectively. Eight patients survived for > 2 years, and there was no distant metastasis in five of these patients after 2 years. No severe side-effects occurred.

CONCLUSIONS

The results suggest that long-term survival can be achieved using PBT for patients with unresectable ICC without distant metastasis. Further studies are required to determine the optimal treatment schedule and best combination of PBT and chemotherapy.

Charged particle therapy versus photon therapy for patients with hepatocellular carcinoma: a systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis to compare the clinical outcomes and toxicity of hepatocellular carcinoma (HCC) patients treated with charged particle therapy (CPT) with those of individuals receiving photon therapy.

METHODS

We identified relevant clinical studies through searching databases. Primary outcomes of interest were overall survival (OS) at 1, 3, 5 years, progression-free survival (PFS), and locoregional control (LC) at longest follow-up.

RESULTS

73 cohorts from 70 non-comparative observational studies were included. Pooled OS was significantly higher at 1, 3, 5 years for CPT than for conventional radiotherapy (CRT) [relative risk (RR) 1·68, 95% CI 1·22-2·31; p<0·001; RR 3.46, 95% CI: 1.72-3.51, p<0.001; RR 25.9, 95% CI: 1.64-408.5, p=0.02; respectively]. PFS and LC at longest follow-up was also significantly higher for CPT than for CRT (p=0·013 and p<0.001, respectively), while comparable efficacy was found between CPT and SBRT in terms of OS, PFS and LC at longest follow-up. Additionally, high-grade acute and late toxicity associated with CPT was lower than that of CRT and SBRT.

CONCLUSION

Survival rates for CPT are higher than those for CRT, but similar to SBRT in patients with HCC. Toxicity tends to be lower for CPT compared to photon radiotherapy.

A prospective feasibility study of respiratory-gated proton beam therapy for liver tumors

PURPOSE

To evaluate the feasibility of a respiratory-gated proton beam therapy for liver tumors.

METHODS AND MATERIALS

Fifteen patients were enrolled in a prospective institutional review board-approved protocol. Eligibility criteria included Childs-Pugh A/B cirrhosis, unresectable biopsy- proven hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), or metastatic disease (solid tumors only), 1-3 lesions, and tumor size of ≤6 cm. Patients received 15 fractions to a total dose of 45-75 GyE [gray equivalent] using respiratory-gated proton beam therapy. Gating was performed with an external respiratory position monitoring based system.

RESULTS

Of the 15 patients enrolled in this clinical trial, 11 had HCC, 3 had ICC, and 1 had metastasis from another primary. Ten patients had a single lesion, 3 patients had 2 lesions, and 2 patients had 3 lesions. Toxicities were grade 3 bilirubinemia-2, grade 3 gastrointestinal bleed-1, and grade 5 stomach perforation-1. One patient had a marginal recurrence, 3 had hepatic recurrences elsewhere in the liver, and 2 had extrahepatic recurrence. With a median follow-up for survivors of 69 months, 1-, 2-, and 3-year overall survivals are 53%, 40%, and 33%, respectively. Progression-free survivals are 40%, 33%, and 27% at 1, 2, and 3 years, respectively.

CONCLUSIONS

Respiratory-gated proton beam therapy for liver tumors is feasible. Phase 2 studies for primary liver tumors and metastatic tumors are underway.

A phase I study on combined therapy with proton-beam radiotherapy and in situ tumor vaccination for locally advanced recurrent hepatocellular carcinoma

Background

Proton-beam radiotherapy (PBT) has been shown to be effective to hepatocellular carcinoma (HCC) as a nonsurgical local treatment option. However, HCC still remains as one of the most difficult cancers to be cured because of frequent recurrences. Thus, methods to inhibit the recurrence need to be explored. To prevent the HCC recurrence, we here report on a prospective phase I study of ‘in situ’ tumor vaccination using CalTUMP, a newly developed immunoadjuvant consisting of BCG extract bound to hydroxyapatite and microparticulated tuberculin, following local PBT for HCC.

Methods

Patients with locally advanced recurrent HCC, which had been heavily pretreated with various treatments, were enrolled. PBT was performed with the conventional method to the target HCC. Subsequently, CalTUMP was injected into the same irradiated-tumor three times at one-week intervals. Three dose-levels of CalTUMP (1/10, 1/3, and 1/1) were administered to 3 patients each. Vital signs, blood samples, ultrasound, and computed tomographic scans were monitored to evaluate the safety.

Results

Three intratumoral injections of CalTUMP following PBT (median dose: 72.6 GyE) were accomplished in 9 patients. Transient low-grade fever and minor laboratory changes were observed in 7 patients after CalTUMP injections. No other treatment-related adverse events were observed. Median progression-free survival was 6.0 months (range: 2.1-14.2) and 4 patients were progression-free for more than 1 year.

Conclusions

Intratumoral injection of CalTUMP following PBT was feasible and safe in patients with heavily pre-treated HCC. Further clinical studies to evaluate the efficacy of this in situ tumor vaccination are warranted.

Hepatocellular carcinoma radiation therapy: review of evidence and future opportunities

Hepatocellular carcinoma (HCC) is a leading cause of global cancer death. Curative therapy is not an option for most patients, often because of underlying liver disease. Experience in radiation therapy (RT) for HCC is rapidly increasing. Conformal RT can deliver tumoricidal doses to focal HCC with low rates of toxicity and sustained local control in HCC unsuitable for other locoregional treatments. Stereotactic body RT and particle therapy have been used with long-term control in early HCC or as a bridge to liver transplant. RT has also been effective in treating HCC with portal venous thrombosis. Patients with impaired liver function and extensive disease are at increased risk of toxicity and recurrence. More research on how to combine RT with other standard and novel therapies is warranted. Randomized trials are also needed before RT will be generally accepted as a treatment option for HCC. This review discusses the current state of the literature and opportunities for future research.

Results of proton beam therapy without concurrent chemotherapy for patients with unresectable stage III non-small cell lung cancer

INTRODUCTION

This study was performed retrospectively to evaluate the outcome of patients with stage III non-small cell lung cancer (NSCLC) after proton beam therapy (PBT) alone.

METHODS

The subjects were 57 patients with histologically confirmed NSCLC (stage IIIA/IIIB: 24/33) who received PBT without concurrent chemotherapy. The cohort included 32 cases of squamous cell carcinoma, 18 adenocarcinoma, and 7 non-small cell carcinoma. Lymph node metastases were N0 7, N1 5, N2 30, and N3 15. Planned total doses ranged from 50 to 84.5 GyE (median, 74 GyE).

RESULTS

Planned treatment was completed in 51 patients (89%). At the time of analysis, 20 patients were alive, and the median follow-up periods were 16.2 months for all patients and 22.2 months for survivors. The median overall survival period was 21.3 months (95% confidence interval: 14.2-28.4 months), and the 1- and 2-year overall survival rates were 65.5% (52.9-78.0%) and 39.4% (25.3-53.5%), respectively. Disease progression occurred in 38 patients, and the 1- and 2-year progression-free survival rates were 36.2% (23.1-49.4%) and 24.9% (12.7-37.2%), respectively. Local recurrence was observed in 13 patients, and the 1- and 2-year local control rates were 79.1% (66.8-91.3%) and 64.1% (47.5-80.7%), respectively. Grade ≥ 3 lung toxicity was seen in six patients, esophageal toxicity occurred at grade ≤ 2, and there was no cardiac toxicity.

CONCLUSION

The prognosis of patients with unresectable stage III NSCLC is poor without chemotherapy. Our data suggest that high-dose PBT is beneficial and tolerable for these patients.

Evaluation of liver function after proton beam therapy for hepatocellular carcinoma

PURPOSE

Our previous results for treatment of hepatocellular carcinoma with proton beam therapy (PBT) revealed excellent local control. In this study, we focused on the impact of PBT on normal liver function.

METHODS AND MATERIALS

The subjects were 259 patients treated with PBT at the University of Tsukuba between January 2001 and December 2007. We evaluated the Child-Pugh score pretreatment, on the final day of PBT, and 6, 12, and 24 months after treatment with PBT. Patients who had disease progression or who died with tumor progression at each evaluation point were excluded from the analysis to rule out an effect of tumor progression. An increase in the Child-Pugh score of 1 or more was defined as an adverse event.

RESULTS

Of the 259 patients, 241 had no disease progression on the final day of PBT, and 91 had no progression within 12 months after PBT. In univariate analysis, the percentage volumes of normal liver receiving at least 0, 10, 20, and 30 GyE in PBT (V0, 10, 20, and 30) were significantly associated with an increase of Child-Pugh score at 12 months after PBT. Of the 91 patients evaluated at 12 months, 66 had no increase of Child-Pugh score, 15 had a 1-point increase, and 10 had an increase of ≥2 points. For the Youden index, the optimal cut-offs for V0, V10, V20, and V30 were 30%, 20%, 26%, and 18%, respectively.

CONCLUSION

Our findings indicate that liver function after PBT is significantly related to the percentage volume of normal liver that is not irradiated. This suggests that further study of the relationship between liver function and PBT is required.

An evidence based review of proton beam therapy: the report of ASTRO's emerging technology committee

Proton beam therapy (PBT) is a novel method for treating malignant disease with radiotherapy. The purpose of this work was to evaluate the state of the science of PBT and arrive at a recommendation for the use of PBT. The emerging technology committee of the American Society of Radiation Oncology (ASTRO) routinely evaluates new modalities in radiotherapy and assesses the published evidence to determine recommendations for the society as a whole. In 2007, a Proton Task Force was assembled to evaluate the state of the art of PBT. This report reflects evidence collected up to November 2009. Data was reviewed for PBT in central nervous system tumors, gastrointestinal malignancies, lung, head and neck, prostate, and pediatric tumors. Current data do not provide sufficient evidence to recommend PBT in lung cancer, head and neck cancer, GI malignancies, and pediatric non-CNS malignancies. In hepatocellular carcinoma and prostate cancer and there is evidence for the efficacy of PBT but no suggestion that it is superior to photon based approaches. In pediatric CNS malignancies PBT appears superior to photon approaches but more data is needed. In large ocular melanomas and chordomas, we believe that there is evidence for a benefit of PBT over photon approaches. PBT is an important new technology in radiotherapy. Current evidence provides a limited indication for PBT. More robust prospective clinical trials are needed to determine the appropriate clinical setting for PBT.

Charged-particle therapy for hepatocellular carcinoma

Historically, the use of external-beam radiotherapy for hepatocellular carcinoma (HCC) has been limited by toxicity to the uninvolved liver and surrounding structures. Advances in photon radiotherapy have improved dose conformality to the tumor and facilitated dose escalation, a key contributor to improved HCC radiation treatment outcomes. However, despite these advances in photon radiotherapy, significant volumes of liver still receive low doses of radiation that can preclude dose escalation, particularly in patients with limited functional liver reserves. By capitalizing on the lack of exit dose along the beam path beyond the tumor and higher biological effectiveness, charged-particle therapy offers the promise of maximizing tumor control via dose escalation without excessive liver toxicity. In this review, we discuss the distinctive biophysical attributes of both proton and carbon ion radiotherapy, particularly as they pertain to treatment of HCC. We also review the available literature regarding clinical outcomes and the toxicity of using charged particles for the treatment of HCC.

Phase i study evaluating the treatment of patients with hepatocellular carcinoma (HCC) with carbon ion radiotherapy: the PROMETHEUS-01 trial

Background

Treatment options for patients with advanced hepatocellular carcinoma (HCC) are often limited. In most cases, they are not amenable to local therapies including surgery or radiofrequency ablation. The multi-kinase inhibitor sorafenib has shown to increase overall survival in this patient group for about 3 months.

Radiation therapy is a treatment alternative, however, high local doses are required for long-term local control. However, due to the relatively low radiation tolerance of liver normal tissue, even using stereotactic techniques, delivery of sufficient doses for successful local tumor control has not be achieved to date.

Carbon ions offer physical and biological characteristics. Due to their inverted dose profile and the high local dose deposition within the Bragg peak precise dose application and sparing of normal tissue is possible. Moreover, in comparison to photons, carbon ions offer an increased relative biological effectiveness (RBE), which can be calculated between 2 and 3 depending on the HCC cell line as well as the endpoint analyzed.

Japanese Data on the evaluation of carbon ion radiation therapy showed promising results for patients with HCC.

Methods/Design

In the current Phase I-PROMETHEUS-01-Study, carbon ion radiotherapy will be evaluated for patients with advanced HCC. The study will be performed as a dose-escalation study evaluating the optimal carbon ion dose with respect to toxicity and tumor control.

Primary endpoint is toxicity, secondary endpoint is progression-free survival and response.

Discussion

The Prometheus-01 trial ist the first trial evaluating carbon ion radiotherapy delivered by intensity-modulated rasterscanning for the treatment of HCC. Within this Phase I dose escalation study, the optimal dose of carbon ion radiotherapy will be determined.

Trial registration

NCT 01167374

Proton beam therapy for hepatocellular carcinoma: a comparison of three treatment protocols

BACKGROUND

Our previous results for treatment of hepatocellular carcinoma (HCC) with proton beam therapy revealed excellent local control with low toxicity. Three protocols were used to avoid late complications such as gastrointestinal ulceration and bile duct stenosis. In this study, we examined the efficacy of these protocols.

METHODS AND MATERIALS

The subjects were 266 patients (273 HCCs) treated by proton beam therapy at the University of Tsukuba between January 2001 and December 2007. Three treatment protocols (A, 66 GyE in 10 fractions; B, 72.6 GyE in 22 fractions; and C, 77 GyE in 35 fractions) were used, depending on the tumor location.

RESULTS

Of the 266 patients, 104, 95, and 60 patients were treated with protocols A, B, and C, respectively. Seven patients with double lesions underwent two different protocols. The overall survival rates after 1, 3 and 5 years were 87%, 61%, and 48%, respectively (median survival, 4.2 years). Multivariate analysis showed that better liver function, small clinical target volume, and no prior treatment (outside the irradiated field) were associated with good survival. The local control rates after 1, 3, and 5 years were 98%, 87%, and 81%, respectively. Multivariate analysis did not identify any factors associated with good local control.

CONCLUSIONS

This study showed that proton beam therapy achieved good local control for HCC using each of three treatment protocols. This suggests that selection of treatment schedules based on tumor location may be used to reduce the risk of late toxicity and maintain good treatment efficacy.

Current clinical evidence for proton therapy

Proton beam therapy provides the opportunity for more localized delivery of ionizing radiation with the potential for improved normal tissue avoidance to reduce treatment related morbidity and to allow for dose escalation to improve disease control and survival without increased toxicity. However, a systematic review of published peer-reviewed literature reported previously and updated here is devoid of any clinical data demonstrating benefit in terms of survival, tumor control, or toxicity in comparison with best conventional treatment for any of the tumors so far treated including skull base and ocular tumors, prostate cancer and childhood malignancies. The current lack of evidence for benefit of protons should provide a stimulus for continued research. Well designed in silico clinical trials using validated normal tissue complication probability-models are important to predict the magnitude of benefit for individual tumor sites but the future use of protons should be guided by clear evidence of benefit demonstrated in well-designed prospective studies, away from commercial influence, and this is likely to require international collaboration. Any complex and expensive technology, including proton therapy, should not be employed on the basis of belief alone and requires testing to avoid inappropriate use of potential detriment to future patients.

Proton beam therapy for large hepatocellular carcinoma

PURPOSE

To investigate the safety and efficacy of proton beam therapy (PBT) in patients with large hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

Twenty-two patients with HCC larger than 10 cm were treated with proton beam therapy at our institution between 1985 and 2006. Twenty-one of the 22 patients were not surgical candidates because of advanced HCC, intercurrent disease, or old age. Median tumor size was 11 cm (range, 10-14 cm), and median clinical target volume was 567 cm(3) (range, 335-1,398 cm(3)). Hepatocellular carcinoma was solitary in 18 patients and multifocal in 4 patients. Tumor types were nodular and diffuse in 18 and 4 patients, respectively. Portal vein tumor thrombosis was present in 11 patients. Median total dose delivered was 72.6 GyE in 22 fractions (range, 47.3-89.1 GyE in 10-35 fractions).

RESULTS

The median follow-up period was 13.4 months (range, 1.5-85 months). Tumor control rate at 2 years was 87%. One-year overall and progression-free survival rates were 64% and 62%, respectively. Two-year overall and progression-free survival rates were 36% and 24%, respectively. The predominant tumor progression pattern was new hepatic tumor development outside the irradiated field. No late treatment-related toxicity of Grade 3 or higher was observed.

CONCLUSIONS

The Bragg peak properties of PBT allow for improved conformality of the treatment field. As such, large tumor volumes can be irradiated to high doses without significant dose exposure to surrounding normal tissue. Proton beam therapy therefore represents a promising modality for the treatment of large-volume HCC. Our study shows that PBT is an effective and safe method for the treatment of patients with large HCC.

A prospective study of hypofractionated proton beam therapy for patients with hepatocellular carcinoma

PURPOSE

To evaluate the efficacy and safety of hypofractionated proton beam therapy for patients with hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

Between September 2001 and August 2004, 51 patients with HCC greater than 2 cm away from the porta hepatis or gastrointestinal tract were treated with proton beam therapy to 66 Gy-equivalents (GyE) in 10 fractions.

RESULTS

Overall survival rates were 49.2 and 38.7% at 3 and 5 years after treatment. Local control rates were 94.5 and 87.8% at 3 and 5 years after treatment. Posttreatment serum alpha-fetoprotein values were significantly reduced when compared with pretreatment values (p < 0.0001). Patients experienced only minor acute reactions of Grade 1 or less, and 3 patients experienced late sequelae of Grade 2 or higher. However, there were no treatment-related deaths.

CONCLUSIONS

Hypofractionated proton beam therapy is safe and well-tolerated by patients with HCC located greater than 2 cm away from the porta hepatis or gastrointestinal tract and may be effective alternative to other modalities.