Emerging role of stereotactic body radiotherapy in the treatment of pancreatic cancer

Stereotactic Radiotherapy for Pancreatic Cancer: A Single-Institution Experience

Introduction

Despite treatment advances, the prognosis of locally advanced pancreatic cancer is poor. Treatment remains varied and includes systemic and radiotherapy (RT). Stereotactic body radiotherapy (SBRT), highly conformal high-dose RT per fraction, is an emerging treatment option.

Materials and methods

We performed a single-institution retrospective review of patients with pancreatic adenocarcinoma treated with SBRT from 2015-2017. The median dose was 27 Gy (range: 21-36 Gy) in three fractions. Endpoints included local progression (RECIST 1.1; Response Evaluation Criteria in Solid Tumors 1.1), distant metastasis, overall survival, and toxicity.

Results

Forty-one patients were treated, with a median follow-up of eight months. Patients who received SBRT had unresectable (49%), metastatic (17%), or borderline resectable (7%) disease, declined surgery (17%), medically inoperable (7%), or developed local recurrence following the Whipple procedure (2%). The six-month and one-year rates of local progression-free survival, distant metastasis-free survival, and overall survival were 62% and 55%, 44% and 32%, and 70% and 49%, respectively. Five patients (12%) experienced seven late gastrointestinal (GI) grade 3 events.

Conclusion 

SBRT may be considered a treatment option to achieve local control of pancreatic cancer and is associated with a modest risk of severe late GI toxicities. Systemic therapies remain important, given the proportion of patients who develop distant metastases.

Irreversible electroporation versus radiotherapy after induction chemotherapy on survival in patients with locally advanced pancreatic cancer: a propensity score analysis

BACKGROUND

Locally advanced pancreatic cancer (LAPC) represents more than one third of pancreatic cancers and owns poor survival after the standard chemotherapy. Irreversible electroporation (IRE) is a novel method and has been recently used in LAPC. The aim of this study was to compare the efficacy of IRE and radiotherapy after induction chemotherapy for patients with LAPC.

METHODS

From August 2015 to August 2017, a total of 76 patients with biopsy proven LAPC and who had received IRE or radiotherapy after chemotherapy were included. Thirty-two pairs of patients were selected through propensity score matching (PSM) analysis and the efficacy of two treatments was compared.

RESULTS

Before PSM analysis, after induction chemotherapy, patients with LAPC benefited more in terms of overall survival (OS) and progression free survival (PFS) from IRE, compared with radiotherapy (2-year OS rates, 53.5% vs 26.9%, p = 0.039; 2-year PFS rates, 28.4% vs 13.3%, p = 0.045). After PSM analysis, the survival benefits of OS and PFS of patients after induction chemotherapy followed by IRE were more obvious than those of patients treated with radiotherapy (2-year OS rates, 53.5% vs 20.7%, p = 0.011; 2-year PFS rates, 28.4% vs 5.6%, p = 0.004). Multivariate Cox regression analysis indicated that IRE after induction chemotherapy was identified as a significant favourable factor for both OS and PFS in both the whole and matched cohort.

CONCLUSIONS

Induction chemotherapy followed by IRE is superior to induction chemotherapy followed by radiotherapy for treating LAPC. A randomized clinical trial comparing the efficacy of IRE and radiotherapy after the induction chemotherapy is therefore considerable.

Irreversible Electroporation in pancreatic ductal adenocarcinoma: Is there a role in conjunction with conventional treatment?

BACKGROUND

The incidence of pancreatic ductal adenocarcinoma (PDAC) is rapidly increasing. Up to 30% of patients present with locally advanced disease and therefore are not candidates for surgery. Locally advanced pancreatic cancer (LAPC) is an emerging entity lacking in level III evidence-based recommendations for its treatment. Currently, systemic chemotherapy is the main treatment for LAPC. However, due to lack of response or disease progression, downsizing of the tumour, making it resectable is successful in only a small proportion of patients. Radiotherapy is often advocated to improve local disease control if there is stability following chemotherapy. Recently, Irreversible Electroporation (IRE), a novel non-thermal ablation technique, has been proposed for the treatment of LAPC.

AIMS AND METHODS

This narrative review aims to explore the potential role and timing for the use of IRE in patients with LAPC.

RESULTS

To date, there is limited and inconsistent level I and II evidence available in the literature regarding the use of IRE for the treatment of PDAC.

DISCUSSION

Although some of the preliminary experience of the use of IRE in patients with LAPC is encouraging, it should only be used after conventional evidence-based treatments and/or within the research context.

Safety and efficacy of stereotactic body radiation therapy combined with S-1 simultaneously followed by sequential S-1 as an initial treatment for locally advanced pancreatic cancer (SILAPANC) trial: study design and rationale of a phase II clinical trial

INTRODUCTION

Upfront surgeries are not beneficial to most patients with pancreatic cancer. Therefore, more emphasis has been placed chemoradiotherapy in locally advanced pancreatic cancer recently. Gemcitabine-based regimens or FOLFIRINOX (a chemotherapy regimen including leucovorin, 5-FU, irinotecan, oxaliplatin) has been proven as a standard chemotherapy in pancreatic cancer. However, severe toxicities may prevent the completion of chemotherapy. S-1 has showed better objective response rates, similar overall survival rates and progression-free survival rates compared with gemcitabine, revealing that S-1 may be a potential candidate in treating pancreatic cancer, especially for patients refractory to gemcitabine. Additionally, stereotactic body radiation therapy with Cyberknife could provide better efficacy than conventional radiotherapy in pancreatic cancer. Therefore, Cyberknife with S-1 simultaneously followed by sequential S-1 as an initial treatment may bring about favourable outcomes but needs further studies.

METHODS AND ANALYSIS

The S-1 as an initial treatment for locally advanced pancreatic cancer (SILAPANC) trial is a prospective, single-centre, one armed ongoing study. 190 eligible patients are required to initially receive Cyberknife with 1 cycle of S-1 simultaneously. After the concurrent chemoradiotherapy, 2 or 3 cycles of S-1 are sequentially given. Doses and fractions depend on the locations and volumes of tumours and the adjacent organs at risk. S-1 is taken orally, 2 times a day, at a dose of 80 mg/m² for 28 days, followed by a 14-day interval. The primary objectives are overall survival and 1-year, 2-year, 3-year, 4-year and 5-year overall survival rates. The secondary objectives are cancer-specific survival, progression-free survival, time to progression, local control rates, clinical benefit rates, radiation-induced acute and late toxicities, adverse effects of chemotherapy and quality of life of patients. Besides, variables most predictive of prognosis would be identified via multivariate methods.

ETHICS AND DISSEMINATION

Approvals have been granted by the Changhai Hospital Ethics Committee (CHEC-2016-032-01). The results will be disseminated in peer-reviewed journals and at conferences.

TRIAL REGISTRATION NUMBER

NCT02704143; Pre-results.

Stereotactic body radiotherapy for pancreatic cancer: recent progress and future directions

Despite advances in surgical, medical, and radiation therapy for pancreatic cancer, the prognosis remains poor. At this time, the only chance for long-term survival is surgical resection. More challenging is the optimal management of unresectable locally advanced pancreatic cancer, which has historically been treated with concurrent chemoradiation or chemotherapy alone. However, the survival and local control benefit of conventional radiotherapy in addition to chemotherapy was unclear. More recently, stereotactic body radiotherapy (SBRT) is emerging as a viable approach to maximizing local tumor control with a tolerable side effect profile. SBRT achieves sharp dose fall-off facilitating safe delivery of highly focused radiation to the tumor over 1-5 days. Although the optimal regimen of pancreas SBRT has not yet been established, its short treatment course limits the delay of additional. Future directions involve prospective study of pancreas SBRT and exploration of biomarkers and imaging technology in order to adopt a personalized management paradigm.

Emerging applications of stereotactic body radiotherapy

Stereotactic body radiotherapy (SBRT) has been used extensively in patients with lung, liver and spinal tumors, and the treatment outcomes are very favorable. For certain conditions such as medically inoperable stage I non-small-cell lung cancer, liver and lung oligometastases, primary liver cancer and spinal metastases, SBRT is regarded as one of the standard therapies. In the recent years, the use of SBRT has been extended to other disease conditions and sites such as recurrent head and neck cancer, renal cell carcinoma, prostate cancer, adrenal metastasis, pancreatic cancer, gynecological malignancies, spinal cord compression, breast cancer, and stage II-III non-small-cell lung cancer. Preliminary data in the literature show promising results but the follow-up intervals are short for most studies. This paper will provide an overview of these emerging applications.

SBRT in pancreatic cancer: what is the therapeutic window?

PURPOSE/OBJECTIVE

To analyse outcome and toxicity of stereotactic body radiotherapy (SBRT) in pancreatic cancer (PDAC).

MATERIAL/METHODS

We systematically reviewed full reports on outcome and toxicity transforming prescription doses to equivalent doses of 2 Gy (EQD2) and biological equivalent doses (BED). Pearson product-moment correlation coefficient, regression analysis and Lyman-Kutcher-Burman modelling were used.

RESULTS

Sixteen trials (572 patients) were identified. Local control correlated with dose. Additionally 4 upper gastrointestinal-SBRT trials (149 patients) were included for toxicity analysis. Acute toxicity was mild but late toxicity ⩾G2 was substantial and predominantly gastrointestinal. Late toxicity ⩾G2 and ⩾G3 correlated highly with EQD2/BED after linear (R(2)=0.85 and 0.77, respectively) and Lyman-Kutcher-Burman modelling. Linear regression lines indicated ⩾G2 and ⩾G3 toxicity frequencies of 5% at 65 Gy and 80 Gy EQD2-α/β=3, respectively. A comparison of toxicity with dose constraints for duodenum revealed partly inadequate dose constraints.

CONCLUSION

RESULTS from multiple fraction regimens could be successfully interpreted to estimate toxicity according to EQD2/BED prescription doses, and dose constraints for the duodenum were derived, whereas local control appeared to be less dose-dependent. This analysis may be useful to plan clinical trials for SBRT and hypofractionated radiotherapy in pancreatic cancer.

Stereotactic radiation therapy of renal cancer inferior vena cava tumor thrombus

Renal Cell Carcinoma (RCC) is a common malignancy world-wide that is rising in incidence. Up to 10% of RCC patients present with inferior vena cava (IVC) tumor thrombus (IVC-TT). Although surgery is the only treatment with proven efficacy for IVC-TT, the surgical management of advanced (level III and IV) IVC-TT is difficult with high morbidity and mortality, and offers a poor survival outcome. Currently, there are no treatment options in the setting of recurrent or unresectable RCC IVC-TT. Even though RCC may be resistant to conventionally fractionated radiation therapy, hypofractionated radiation has shown excellent control rates for both primary and metastatic RCC. We report our experience treating 2 RCC patients with Level IV IVC-TT -one recurrent and the other unresectable-with stereotactic ablative radiation therapy (SABR). The first patient is a 75-year-old gentleman with a level IV RCC IVC-TT who presented 9 months after his radical nephrectomy and thrombectomy with a growing level IV IVC-TT that became refractory to 4 targeted agents. He received SABR of 50Gy in 5 fractions and at 2-year follow-up is doing well with a significant decrease in the enhancement and size of the IVC-TT. The second patient is an 83-year-old gentleman who presented with metastatic RCC and level IV IVC-TT but was not a surgical candidate. After progression on temsirolimus, he received SABR of 36Gy in 4 fractions to his IVC-TT and survived 18 months post-SABR. Both patients improved symptomatically and did not experience any acute or late treatment-related toxicity. Their survival of 24 months and 18 months are comparable to the reported median survival of 20 months in patients with level IV IVC-TT that underwent surgical resection. Therefore, SABR can be a potentially safe treatment option in the unresectable setting for RCC patients with IVC-TT and should be further evaluated in prospective trials.

Is concomitant radiotherapy necessary with gemcitabine-based chemotherapy in pancreatic cancer?

AIM: To evaluate the efficacy and safety of gemcitabine (GEM) plus radiotherapy compared with GEM alone for pancreatic cancer (PC).

METHODS: A systematic search for eligible studies comparing gemcitabine plus radiotherapy with gemcitabine alone for PC was performed using MEDLINE, EMBASE, and the Cochrane Library. A quality assessment was performed in each study. Meta-analyses were performed to study the pooled effects of relative risk with 95% confidence interval (CI).

RESULTS: A total of 336 participants from four original studies were included. Gemcitabine plus radiotherapy resulted in comparable overall survival (HR = 0.84, 95%CI: 0.53-1.34, P = 0.48) and progress free survival (HR = 0.99, 95%CI: 0.97-1.01, P = 0.36) to gemcitabine alone. Moreover, concomitant radiotherapy was associated with a significantly higher incidence of severe (grade 3 or greater) toxicities, mainly anemia, leukocytopenia, thrombocytopenia, anorexia, nausea/vomiting, and asthenia/fatigue.

CONCLUSION: Radiotherapy is not beneficial with gemcitabine-based chemotherapy for PC. Further exploration for better radiotherapy approaches and therapeutic regimens for the treatment of PC is warranted.

Best of International Stereotactic Radiosurgery Society Congress 2013: stereotactic body radiation therapy. Part II: nonspinal tumors

The 11th biennial International Stereotactic Radiosurgery Society Congress represented another historical gathering of professionals in the field of stereotactic radiosurgery. This congress was held on 16-20 June 2013 in Toronto (ON, Canada), and the chairman was Arjun Sahgal, co-chair was Michael Schwartz and president of the society was Jean Regis. The congress attracted 550 attendants from all over the world and over 300 abstracts were presented. Among the abstracts presented, 62 (36 oral) were pertaining to stereotactic body radiation therapy (SBRT). Exciting new findings were presented by colleagues from North America, Europe and Asia. This short conference scene (part II) provides a summary of the best abstracts on SBRT for nonspinal tumors presented in the congress. A separate conference scene on SBRT for spinal tumors (part I) also appears in this issue of Future Oncology.

Management of borderline and locally advanced pancreatic cancer: Where do we stand?

Many patients with pancreas cancer present with locally advanced pancreatic cancer (LAPC). The principle tools used for diagnosis and staging of LAPC include endoscopic ultrasound, axial imaging with computed tomography and magnetic resonance imaging, and diagnostic laparoscopy. The definition of resectability has historically been vague, as there is considerable debate and controversy as to the definition of LAPC. For the patient with LAPC, there is some level of involvement of the surrounding vascular structures, which include the superior mesenteric artery, celiac axis, hepatic artery, superior mesenteric vein, or portal vein. When feasible, most surgeons would recommend possible surgical resection for patients with borderline LAPC, with the goal of an R0 resection. For initially unresectable LAPC, neoadjuvant should be strongly considered. Specifically, these patients should be offered neoadjuvant therapy, and the tumor should be assessed for possible response and eventual resection. The efficacy of neoadjuvant therapy with this approach as a bridge to potential curative resection is broad, ranging from 3%-79%. The different modalities of neoadjuvant therapy include single or multi-agent chemotherapy combined with radiation, chemotherapy alone, and chemotherapy followed by chemotherapy with radiation. This review focuses on patients with LAPC and addresses recent advances and controversies in the field.