Chemoradiation and brachytherapy in extrahepatic bile duct carcinoma

Ablative therapies of the biliary tree

Cholangiocarcinoma, a malignancy of the epithelial cells in the intrahepatic or extrahepatic biliary tree, is often diagnosed at later stages. Median survival duration ranges from 3 to 9 months with a less than ten percent 5-year survival rate. Thus, often treatment strategies are aimed more towards palliation instead of cure. With the majority of patients presenting with unresectable disease at the time of diagnosis, surgical intervention is not feasible, making less invasive endoscopic therapies more suitable. Initially, biliary stents were utilized for biliary decompression to mitigate cholestatic symptoms and prevent cholangitis; however, this strategy did not prove to provide significant survival benefit. Therefore, efforts to treat the tumor burden itself in addition to maintaining biliary patency became a focus of innovation and research in the endoscopic field. This study has led to the advent of therapies such as photodynamic therapy, radiofrequency ablation, and intraluminal brachytherapy. These options combined with biliary stenting have shown to not only offer the benefit of biliary decompression, but also to potentially improve stent patency and survival. Further, there is an anti-tumor effect of each of these modalities, portending an additional benefit in this subset of patients. Despite numerous retrospective and prospective studies assessing these ablative therapies, there is still a paucity of appropriately powered randomized controlled trials, and further research has yet to be done in the field. This review details the current literature entailing endobiliary ablative strategies.

Non-surgical treatment of hilar cholangiocarcinoma

Cancer of the biliary confluence also known as hilar cholangiocarcinoma (HC) or Klatskin tumor, is a rare type of neoplastic disease constituting approximately 40%-60% of intrahepatic malignancies, and 2% of all cancers. The prognosis is extremely poor and the majority of Klatskin tumors are deemed unresectable upon diagnosis. Most patients with unresectable bile duct cancer die within the first year after diagnosis, due to hepatic failure, and/or infectious complications secondary to biliary obstruction. Curative treatments include surgical resection and liver transplantation in highly selected patients. Nevertheless, very few patients are eligible for surgery or transplant at the time of diagnosis. For patients with unresectable HC, radiotherapy, chemotherapy, photodynamic therapy, and liver-directed minimally invasive procedures such as percutaneous image-guided ablation and intra-arterial chemoembolization are recommended treatment options. This review focuses on currently available treatment options for unresectable HC and discusses future perspectives that could optimize outcomes.

Outcome of postoperative radiation therapy for cholangiocarcinoma and analysis of dose-volume histogram of remnant liver

The aim of this study was to analyze dose-volume histogram (DVH) of the remnant liver for postoperative cholangiocarcinoma (CCA) patients, to find toxicity rates, and to confirm efficacy of postoperative radiation therapy (RT).Thirty-two postoperative CCA patients received partial liver resection and postoperative RT with curative intent. The "liver reduction rate" was calculated by contouring liver volume at computed tomography (CT) just before the surgery and at CT for planning the RT. To evaluate late toxicity, the radiation-induced hepatic toxicity (RIHT) was determined by the common terminology criteria for adverse events toxicity grade of bilirubin, aspartate transaminase, alanine transaminase, alkaline phosphatase, and albumin, and was defined from 3 months after RT until liver metastasis was revealed. The radiation-induced liver disease (RILD) was also evaluated.Tumor stages were distributed as follows: I: 1, II: 8, IIIA: 1, IIIB: 6, IIIC: 14, IVA: 2. Median prescribed total dose was 50 Gy. Median follow-up time was 27 months. Two-year overall survival (OS): 72.4%, disease-free survival: 47.7%, local control: 65.3%, and the median survival time was 40 months. The median "liver reduction rate" was 21%. The OS had statistically significant difference in nodal status (P = .032) and "liver reduction rate" >30% (P = .016). In the association between the ≥grade 2 RIHT and DVH, there were significantly differences in V30 and V40 (P = .041, P = .034), respectively. The grade ≥2 RIHT rates differ also significantly by sex (P = .008). Two patients (6.2%) were suspected of RILD.We suggest that RT for remnant liver should be considered the liver V30, V40 to prevent radiation-induced liver dysfunction.

Endoscopic Retrograde Cholangiopancreatography-Guided Ablation for Cholangiocarcinoma

Most patients with perihilar cholangiocarcinoma present with surgically unresectable disease owing to the insidious nature of this malignancy. Relief of malignant perihilar biliary obstruction is a key aspect of cholangiocarcinoma. Although palliative stenting using uncovered metal stents has been advocated in patients with unresectable malignant perihilar biliary strictures, several endoscopic retrograde cholangiopancreatography-guided ablative modalities have emerged. Palliative photodynamic therapy, radiofrequency ablation, and intraluminal brachytherapy have been associated with improved stent patency and survival, although the ideal treatment approach remains unclear. This article reviews the published evidence for using each of these endobiliary ablative modalities in this difficult-to-treat patient population.

Technique for the administration of high-dose-rate brachytherapy to the bile duct using a nasobiliary catheter

PURPOSE

Cholangiocarcinoma patients who are potential candidates for liver transplantation may be treated with high-dose-rate (HDR) brachytherapy using a minimally invasive nasobiliary catheter in an effort to escalate the radiotherapy dose to the tumor and maximize local control rates. This work describes the equipment, procedures, and quality assurance (QA) that enables successful administration.

METHODS AND MATERIALS

This work describes the nasobiliary catheter placement, simulation, treatment planning, treatment delivery, and QA. In addition, a chart review was performed of all patients who received endoscopic retrograde cholangiopancreatography for HDR bile duct brachytherapy at our institution from 2007 to 2017. The review evaluated how many patients were treated and the number of patients who could not be treated because of anatomic and/or equipment limitations.

RESULTS

From 2007 to 2017, 122 cholangiocarcinoma patients have been treated with HDR brachytherapy using a nasobiliary catheter. Three patients underwent catheter placement but did not receive brachytherapy treatment due to catheter migration between placement and treatment or because the HDR afterloader was unable to extend the source wire into the treatment site. Periodic QA is recommended for ensuring whether the HDR afterloader is capable of extending the source wire through an extensive and curved path.

CONCLUSIONS

Intraluminal HDR brachytherapy with a nasobiliary catheter can be successfully administered. Procedures and QA are described for ensuring safety and overcoming technical challenges.

An atlas for clinical target volume definition, including elective nodal irradiation in definitive radiotherapy of biliary cancer

Radiotherapy (RT) is a treatment option for advanced biliary tract cancer (BTC), often combined with sequential and/or concurrent chemotherapy. The use of modern RT techniques requires accurate clinical target volume (CTV) definition and delineation. However, guidelines for CTV delineation in BTC are lacking. Therefore, the aim of this study was to propose a computer tomography (CT) atlas for CTV definition of BTC. We previously proposed guidelines to define the nodal CTV (CTV-N) in BTC. In this study, based on a literature analysis, we defined the margins to be added to the gross tumor volume (GTV; subclinical and microscopic disease) to define the primary tumor CTV (CTV-T). An abdominal contrast enhanced planning CT scan was performed on three different patients with unresectable intrahepatic cholangiocarcinoma (CC), extrahepatic CC and gallbladder cancer. The GTV and anatomical reference structures were outlined on CT images. Then, based on our guidelines, the CTV-T and CTV-N were delineated and merged to define the final CTV in the three patients. An atlas, showing the defined CTV, was generated from the reference CT images to illustrate the CTV for intra-hepatic CC, extra-hepatic CC and gallbladder cancer. This atlas can be used as an aid for CTV definition in patients with BTC treated with modern RT techniques.

In vitro Dosimetric Study of Biliary Stent Loaded with Radioactive 125I Seeds

Background:

A novel radioactive ¹²⁵I seed-loaded biliary stent has been used for patients with malignant biliary obstruction. However, the dosimetric characteristics of the stents remain unclear. Therefore, we aimed to describe the dosimetry of the stents of different lengths — with different number as well as activities of ¹²⁵I seeds.

Methods:

The radiation dosimetry of three representative radioactive stent models was evaluated using a treatment planning system (TPS), thermoluminescent dosimeter (TLD) measurements, and Monte Carlo (MC) simulations. In the process of TPS calculation and TLD measurement, two different water-equivalent phantoms were designed to obtain cumulative radial dose distribution. Calibration procedures using TLD in the designed phantom were also conducted. MC simulations were performed using the Monte Carlo N-Particle eXtended version 2.5 general purpose code to calculate the radioactive stent's three-dimensional dose rate distribution in liquid water. Analysis of covariance was used to examine the factors influencing radial dose distribution of the radioactive stent.

Results:

The maximum reduction in cumulative radial dose was 26% when the seed activity changed from 0.5 mCi to 0.4 mCi for the same length of radioactive stents. The TLD's dose response in the range of 0–10 mGy irradiation by ¹³⁷Cs γ-ray was linear: y = 182225x − 6651.9 (R²= 0.99152; y is the irradiation dose in mGy, x is the TLDs’ reading in nC). When TLDs were irradiated by different energy radiation sources to a dose of 1 mGy, reading of TLDs was different. Doses at a distance of 0.1 cm from the three stents’ surface simulated by MC were 79, 93, and 97 Gy.

Conclusions:

TPS calculation, TLD measurement, and MC simulation were performed and were found to be in good agreement. Although the whole experiment was conducted in water-equivalent phantom, data in our evaluation may provide a theoretical basis for dosimetry for the clinical application.

Chemoradiation Therapy for Unresected Extrahepatic Cholangiocarcinoma: A Propensity Score-Matched Analysis

BACKGROUND

Unresected extrahepatic cholangiocarcinoma (uEHCC) remains a deadly disease. Guidelines for uEHCC recommend either chemotherapy alone (CT) or chemoradiotherapy (CRT). This study used the National Cancer Database (NCDB) to compare outcomes for patients treated with CT and those who underwent CRT.

METHODS

Patients with initially diagnosed non-metastatic uEHCC from 2004 to 2014 were identified. Using Chi square analysis, patients who underwent CT were compared with those who received CRT. Uni- and multivariate Cox regression analyses were used to compare characteristics related to survival. Propensity score matching and shared frailty analysis were undertaken to correct for baseline differences between the two groups. Additional analyses were performed to compare survival for the minority of patients who underwent surgery and advanced-stage patients.

RESULTS

The study identified 2996 patients with uEHCC. Chemoradiation was associated with better survival (median survival [MS], 14.5 months; hazard ratio [HR] 0.84; p < 0.001) than CT alone (MS, 12.6 months). Induction of CT before CRT was associated with a trend toward decreased risk of death compared with concurrent CRT (HR 0.81; p = 0.051). For the patients able to undergo surgery after initial treatment, MS was 24.5 months (HR 0.38; p < 0.001) versus 12.2 months for those who had no surgery. For these patients, CRT also was associated with better survival (MS, 31.2 months; HR 0.66; p = 0.001) than CT (MS, 22.1 months). Positive margins at surgery yielded survival equivalent to that with no surgery.

CONCLUSION

Although CRT may be associated with slightly better survival in uEHCC than CT alone, the majority of the benefit was observed for patients able to undergo eventual surgery.

Stereotactic Body Radiotherapy (SBRT) for Intrahepatic and Hilar Cholangiocarcinoma

Background: Unresectable intrahepatic and hilar cholangiocarcinomas carry a dismal prognosis. Systemic chemotherapy and conventional external beam radiation and brachytherapy have been used with limited success. We explored the use of stereotactic body radiotherapy (SBRT) for these patients.

Methods: Patients with unresectable intrahepatic or hilar cholangiocarcinoma or those with positive margins were included in this study. Systemic therapy was used at the discretion of the medical oncologist. The Cyberknife^TM stereotactic body radiotherapy system used to treat these patients. Patients were treated with three daily fractions. Clinical and radiological follow-up were performed every three months.

Results: 34 patients (16 male and 18 female) with 42 lesions were included in this study. There were 32 unresectable tumors and two patients with resected tumors with positive margins. The median SBRT dose was 30Gy in three fractions. The median follow-up was 38 months (range 8-71 months). The actuarial local control rate was 79%. The median overall survival was 17 months and the median progression free survival was ten months. There were four Grade III toxicities (12%), including duodenal ulceration, cholangitis and liver abscess.

Conclusions: SBRT is an effective and reasonably safe local therapy option for unresectable intrahepatic or hilar cholangiocarcinoma.

Adjuvant Chemotherapy and Radiation Therapy is Associated with Improved Survival for Patients with Extrahepatic Cholangiocarcinoma

BACKGROUND

This study aimed to analyze adjuvant therapy among patients with extrahepatic cholangiocarcinoma (EHC) at a national level.

METHODS

The American College of Surgeons National Cancer Data Base was used to identify patients with resected EHC (pathologic stages 1-3) between 1998 and 2006 (n = 8741). Three groups were compared: surgery only (S, n = 5766), surgery plus adjuvant chemotherapy (AC, n = 450), and surgery plus adjuvant chemotherapy and radiation therapy (ACR, n = 1918). The study investigated how patient demographics, provider characteristics, and tumor-specific variables were associated with receipt of adjuvant therapy and overall survival.

RESULTS

Patients who received adjuvant treatment were more likely to be younger (median age S, 70 years; AC, 65 years; ACR, 63 years), in the highest income quartile (>$46,000: S, 38.3 %; AC, 43.4 %; ACR, 44.7 %), and treated at a community cancer center (S, 43.0 %; AC, 50.7 %; ACR, 52.9 %) (all p < 0.001). These patients also were more likely to have positive lymph nodes (S, 34.7 %; AC, 69.6 %; ACR, 63.3 %), positive surgical margins (S, 5.9 %; AC, 7.1 %; ACR, 10.7 %), and stage 3 disease (S, 21.4 %; AC, 37.8 %; ACR, 37.9 %) (all p < 0.001). Multivariate analysis of the entire cohort showed improved survival with ACR (hazard ratio [HR] 0.82; 95 % confidence interval [CI] 0.75-0.91). The survival benefit was independent of margin status (R0: HR 0.88; 95 % CI 0.79-0.97; R1: HR 0.49; 95 % CI 0.38-0.62).

CONCLUSIONS

This national analysis suggests that ACR are associated with improved survival for high-risk EHC patients, such as those with positive lymph nodes. Until randomized clinical trials are conducted, these may be the best available data to guide adjuvant therapy for resected EHC.

Future directions in the treatment of cholangiocarcinoma

Cholangiocarcinoma (CCA) comprises a heterogeneous group of cancers with pathologic features of biliary tract differentiation, and is best classified anatomically as intrahepatic CCA (ICC), perihilar (pCCA), or distal (dCCA) CCA. They represent a clinically and genetically diverse collection of cancers. Surgical resection represents the only curative modality for CCA, although there are encouraging data with liver transplantation for early stage pCCA. There is no established adjuvant therapy for CCA. Unfortunately, most patients with CCA will present with unresectable or metastatic disease with poor prognosis. Currently the combination of gemcitabine and cisplatin remains the standard therapy for advanced CCA. No second line therapy has definitely demonstrated improved survival benefits. Development of molecularly targeted therapies in advanced CCA remains challenging. However, recent efforts with targeted and whole exome sequencing have defined the landscape of mutations underlying CCA, particularly ICC. The identification of novel molecular signatures in CCA coupled with molecularly targeted therapy development provides the potential for developing novel therapeutic options in this intractable disease.

Positioning high-dose radiation in multidisciplinary management of unresectable cholangiocarcinomas: review of current evidence

Cholangiocarcinoma is a rare malignancy of the bile ducts. The current standard of care for unresectable nonmetastatic disease is doublet systemic chemotherapy, which provides a median survival of 11.7 months. Although chemoradiation is a therapeutic option that provides almost equivalent or superior survival, the lack of level I evidence presents a major hurdle in routinely recommending it within multidisciplinary clinics. This mini review presents the current evidence on the use of chemoradiation for unresectable nonmetastatic cholangiocarcinoma and rationale for positioning it within multidisciplinary management of unresectable cholangiocarcinomas.