Transarterial Fiducial Marker Placement for Image-guided Proton Therapy for Malignant Liver Tumors

Feasibility of marker-less stereotactic body radiotherapy for hepatocellular carcinoma

BACKGROUND

The feasibility of marker-less stereotactic body radiotherapy (SBRT) for hepatocellular carcinoma (HCC) has not yet been established, and, thus, was examined in the present study.

MATERIAL AND METHODS

We retrospectively investigated patients who received marker-less SBRT for locally untreated HCC tumors between July 2005 and December 2018. Radiotherapy planning CT was performed under fixation with vacuum cushions and abdominal compression. The clinical target volume (CTV) was equivalent to the gross tumor volume (GTV). The internal target volume (ITV) margin to CTV was determined from calculations based on the motion of the diaphragm. The planning target volume (PTV) margin to ITV was 5-6 mm. In the set-up, radiotherapy planning CT and linac-integrated cone-beam CT performed in the same imaging and fixation settings were merged by referring to the anatomical components surrounding target tumors. The primary endpoint was the 3-year cumulative local tumor progression rate. The upper limit of the 95% confidence interval for the 3-year cumulative local tumor progression rate was less than 7.0%, which was interpreted as favorable local control and feasible for marker-less SBRT. Local tumor progression was assessed by mRECIST.

RESULTS

We reviewed 180 patients treated with 35-40 Gy/5 fractions. The median follow-up time for the local tumor progression of censored tumors was 32.3 months (range, 0.3-104). The 3-year cumulative local tumor progression rate was 3.0% (95% CI, 1.1-6.5%). The 3-year overall survival rate was 71.6% (95% CI, 63.5-78.2%). Regarding acute hematologic toxicities, grade 3 hypoalbuminemia and thrombocytopenia were detected in 1 (0.6%) and 5 (2.9%) patients, respectively. Treatment-related death from SBRT was not observed. SBRT was initiated within 7 days after radiotherapy planning CT for 84% (152/180) of patients.

CONCLUSIONS

Marker-less SBRT for HCC achieved favorable local control that fulfilled the threshold. This result suggests that marker-less SBRT with appropriate settings is a feasible treatment strategy.

A Phase 2 Study of Image-Guided Proton Therapy for Operable or Ablation-Treatable Primary Hepatocellular Carcinoma

PURPOSE

Because most previous data on proton therapy for hepatocellular carcinoma (HCC) were retrospectively collected from inoperable or previously treated cases, our aim was to evaluate the outcome of image-guided proton therapy (IGPT) for operable or radiofrequency ablation-treatable primary HCC.

METHODS AND MATERIALS

This phase 2 study prospectively investigated the efficacy and safety of IGPT and quality of life (QoL) after IGPT for operable/ablatable HCC. The primary endpoint was overall survival, and the secondary endpoints were local control, incidence of grade ≥3 adverse events, and changes in QoL. Toxicities were evaluated with Common Terminology Criteria for Adverse Events, version 4.0. QoL scores were assessed with European Organization for Research and Treatment of Cancer Quality of Life Questionnaire, version 3.0, and Quality of Life Questionnaire-Hepatocellular Carcinoma/Primary Liver Cancer Module. IGPT was performed using respiratory-gated techniques.

RESULTS

Forty-five patients (median age: 68 years; range, 36-80 years) were enrolled between June 2013 and February 2016; 38 were considered operable and 14 were indicated for radiofrequency ablation. The major underlying liver diseases were hepatitis B (n = 16), hepatitis C (n = 13), alcoholic hepatitis (n = 3), and nonalcoholic fatty liver disease (n = 13). The Child-Pugh score was A5 in 32 patients, A6 in 9 patients, and B7 in 4 patients. Thirty-seven patients with a peripherally located tumor were given 66 Gy relative biological effectiveness in 10 fractions, and 8 patients with a centrally located tumor received 72.6 Gy relative biological effectiveness in 22 fractions. The median follow-up period of surviving patients was 60 months (range, 42-75 months). Two- and 5-year overall survival rates were 84% (95% confidence interval [CI], 74%-95%) and 70% (95% CI, 56%-84%), respectively, and local control rates were 95% (95% CI, 89%-100%) and 92% (95% CI, 84%-100%), respectively. Grade 3 radiation-induced liver disease was observed in 1 patient. No significant changes were noted in QoL scores 1 year after treatment, except for body image.

CONCLUSIONS

Although the primary endpoint did not meet statistical significance as planned in the study design, IGPT is a safe and effective treatment for solitary primary HCC and may become a treatment option.

Proton therapy range verification method via delayed γ-ray spectroscopy of a molybdenum tumour marker

In this work, a new method of range verification for proton therapy (PT) is experimentally demonstrated for the first time. If a metal marker is implanted near the tumour site, its response to proton activation will result in the emission of characteristic γ rays. The relative intensity of γ rays originating from competing fusion-evaporation reaction channels provides a unique signature of the average proton energy at the marker, and by extension the beam's range, in vivo and in real time. The clinical feasibility of this method was investigated at the PT facility at TRIUMF with a proof-of-principle experiment which irradiated a naturally-abundant molybdenum foil at various proton beam energies. Delayed characteristic γ rays were measured with two Compton-shielded LaBr₃ scintillators. The technique was successfully demonstrated by relating the relative intensity of two γ-ray peaks to the energy of the beam at the Mo target, opening the door to future clinical applications where the range of the beam can be verified in real time.

Effect of a Device-Free Compressed Shell Fixation Method on Hepatic Respiratory Movement: Analysis for Respiratory Amplitude of the Liver and Internal Motions of a Fiducial Marker

PURPOSE

Suppression of respiratory movement of the liver would be desirable for high-precision radiation therapy for liver tumors. We aimed to investigate the effect of our original device-free compressed shell fixation method and breathing instruction on suppression of respiratory movement. The characteristics of liver motion based on the movement of a fiducial marker were also analyzed.

METHODS AND MATERIALS

First, respiratory amplitudes of the liver with the device-free compressed shell were analyzed from the data of 146 patients. The effect of this shell fixing method on liver movement was evaluated. Second, as another cohort study with 166 patients, interfractional internal motion of the liver for patients fixed in the shell was calculated using the fiducial marker coordinate data of images for position setting before daily irradiation. Third, in another 12 patients, intrafractional internal motion was calculated from the fiducial marker coordinate data using x-ray images before and after irradiation.

RESULTS

The median respiratory movement without the shell, after fixing with the shell, and after instructing on the breathing method with the shell was 14.2 (interquartile range, 10.7-19.8), 11.5 (8.6-17.5), and 10.4 mm (7.3-15.8), respectively. Systematic and random errors of interfractional internal motion were all ≤2 mm in the left-right and anteroposterior directions and 3.7 and 3.0 mm, respectively, in the craniocaudal direction. Systematic and random errors of intrafractional internal motion were all ≤1.3 mm in the left-right and anteroposterior directions and 0.8 and 2.4 mm, respectively, in the craniocaudal direction.

CONCLUSIONS

The device-free compressed shell fixation method was effective in suppressing the respiratory movement of the liver. Irradiation position matching using the fiducial marker can correct the interfractional internal motion on each day, which would contribute to the reduction of the margin to be given around the target.

Stereotactic body radiation therapy for hepatocellular carcinoma: Experience from a tertiary cancer care center in India

AIM

The aim of this retrospective study is to assess the toxicity and tumor response of stereotactic body radiation therapy (SBRT) protocol for hepatocellular carcinoma (HCC) in our institution.

BACKGROUND

Hepatocellular cancer is one of the leading cancers among men in India. In recent years, SBRT has emerged as a promising tool in the treatment of HCC.

MATERIALS AND METHODS

Ten patients diagnosed as HCC with Barcelona Clinic Liver Cancer Stage B and C, treated with SBRT technique from January 2013 to December 2016, were included in this study. SBRT was delivered using 6 MV photons with volumetric modulated arc therapy. Acute and late toxicities were graded, and tumor response was assessed using response evaluation criteria in solid tumors criteria. Kaplan-Meier curves were generated for progression-free survival (PFS) and overall survival (OS).

RESULTS

The median age was 61.5 (52-69) years. The radiation dose ranged from 35 Gy to 60 Gy. All patients obtained partial response during assessment at 3 months after completion of treatment. The median PFS is 8 months (95% confidence interval [CI] - 5.22-10.77 months). The median OS is 51 months (95% CI - 17.64-65.10 months). The OS at 1 and 2 years is 75% and 57%, respectively.

CONCLUSIONS

SBRT is well tolerated by our patients. The 1- and 2-year OS of 75% and 57% is consistent with other prospective and retrospective SBRT studies from the literature.

Therapeutic usability of two different fiducial gold markers for robotic stereotactic radiosurgery of liver malignancies: A pilot study

AIM: To assess how the application of different types of markers affects the tracking accuracy of CyberKnife’s.

METHODS: Fifteen patients were recruited and subjected to the ultrasound-guided placement of markers. Two different type of needles 25 gauge (G) and 17 G containing two different fiducial marker, gold notched flexible anchor wire 0.28 mm × 10 mm (25 G needle) and gold cylindrical grain 1 mm × 4 mm (17 G), were used. Seven days after the procedure, a CyberKnife planning computed tomography (CT) for the simulation of radiation treatment was performed on all patients. A binary CT score was assigned to the fiducial markers visualization. Also, the CT number was calculated for each fiducial and the values compared with a specific threshold.

RESULTS: For each patient from 1 to 5, intra-hepatic markers were placed (one in 2 patients, three in 8 patients, four in 3 patients, and five in 2 patients). A total of 48 needles were used (thirty-two 17 G and sixteen 25 G) and 48 gold markers were placed (32 Grain shaped markers and 16 Gold Anchor). The result showed that the CT visualization of the grain markers was better than the anchor markers (P = 5 × 10^-9). Furthermore, the grain markers were shown to present minor late complications (P = 3 × 10^-6), and the best CT threshold number (P = 0.0005).

CONCLUSION: The study revealed that the Gold Anchor fiducial marker is correlated with a greater number of late minor complications and low visualization by the CT.

Percutaneous fiducial marker placement prior to stereotactic body radiotherapy for malignant liver tumors: an initial experience

The aim of this study was to describe our initial experience with a gold flexible linear fiducial marker and to evaluate the safety and technical and clinical efficacy of stereotactic body radiotherapy using this marker for malignant liver tumors. Between July 2012 and February 2015, 18 patients underwent percutaneous fiducial marker placement before stereotactic body radiotherapy for malignant liver tumors. We evaluated the technical and clinical success rates of the procedure and the associated complications. Technical success was defined as successful placement of the fiducial marker at the target site, and clinical success was defined as the completion of stereotactic body radiotherapy without the marker dropping out of position. All 18 fiducial markers were placed successfully, so the technical success rate was 100% (18/18). All 18 patients were able to undergo stereotactic body radiotherapy without marker migration. Thus, the clinical success rate was 100% (18/18). Slight pneumothorax occurred as a minor complication in one case. No major complications such as coil migration or bleeding were observed. The examined percutaneous fiducial marker was safely placed in the liver and appeared to be useful for stereotactic body radiotherapy for malignant liver tumors.