The influence of adjuvant radiotherapy dose on overall survival in patients with resected pancreatic adenocarcinoma

Definition of Local Recurrence Site in Resected Pancreatic Adenocarcinoma: A Multicenter Study (DOLORES-1)

Simple Summary

Pancreatic cancer remains a disease with a dismal outlook for patients, with high relapse rates after surgery and adjuvant treatments. Thanks to the high conformality achievable with advanced radiotherapy techniques, a more robust definition of clinical target volume (CTV) margins is mandatory. Moreover, a precise CTV definition may affect local control, minimizing radiation-related toxicity and allowing dose escalation. Contrary to two recent studies, RTOG contouring guidelines are not based on a pattern of failure analysis. We provided a local failure risk map in resected pancreatic cancer, validating the results of previous studies. Moreover, according to a new probabilistic approach, we provided new CTV contouring guidelines for the postoperative radiotherapy of pancreatic cancer, modeling targets’ margins on a combination of our validated local failure map (30% of local failures) and RTOG guidelines (70% of local failures).

Abstract

The study aimed to generate a local failure (LF) risk map in resected pancreatic cancer (PC) and validate the results of previous studies, proposing new guidelines for PC postoperative radiotherapy clinical target volume (CTV) delineation. Follow-up computer tomography (CT) of resected PC was retrospectively reviewed by two radiologists identifying LFs and plotting them on a representative patient CT scan. The percentages of LF points randomly extracted based on CTV following the RTOG guidelines and based on the LF database were 70% and 30%, respectively. According to the Kernel density estimation, an LF 3D distribution map was generated and compared with the results of previous studies using a Dice index. Among the 64 resected patients, 59.4% underwent adjuvant treatment. LFs closer to the root of the celiac axis (CA) or the superior mesenteric artery (SMA) were reported in 32.8% and 67.2% cases, respectively. The mean (± standard deviation) distances of LF points to CA and SMA were 21.5 ± 17.9 mm and 21.6 ± 12.1 mm, respectively. The Dice values comparing our iso-level risk maps corresponding to 80% and 90% of the LF probabilistic density and the CTVs-80 and CTVs-90 of previous publications were 0.45–0.53 and 0.58–0.60, respectively. According to the Kernel density approach, a validated LF map was proposed, modeling a new adjuvant CTV based on a PC pattern of failure.

Adjuvant chemoradiation in pancreatic cancer: impact of radiotherapy dose on survival

BACKGROUND

To evaluate the impact of radiation dose on overall survival (OS) in patients treated with adjuvant chemoradiation (CRT) for pancreatic ductal adenocarcinoma (PDAC).

METHODS

A multicenter retrospective analysis on 514 patients with PDAC (T1-4; N0-1; M0) treated with surgical resection with macroscopically negative margins (R0-1) followed by adjuvant CRT was performed. Patients were stratified into 4 groups based on radiotherapy doses (group 1: < 45 Gy, group 2: ≥ 45 and < 50 Gy, group 3: ≥ 50 and < 55 Gy, group 4: ≥ 55 Gy). Adjuvant chemotherapy was prescribed to 141 patients. Survival functions were plotted using the Kaplan-Meier method and compared through the log-rank test.

RESULTS

Median follow-up was 35 months (range: 3-120 months). At univariate analysis, a worse OS was recorded in patients with higher preoperative Ca 19.9 levels (≥ 90 U/ml; p < 0.001), higher tumor grade (G3-4, p = 0.004), R1 resection (p = 0.004), higher pT stage (pT3-4, p = 0.002) and positive nodes (p < 0.001). Furthermore, patients receiving increasing doses of CRT showed a significantly improved OS. In groups 1, 2, 3, and 4, median OS was 13.0 months, 21.0 months, 22.0 months, and 28.0 months, respectively (p = 0.004). The significant impact of higher dose was confirmed by multivariate analysis.

CONCLUSIONS

Increasing doses of CRT seems to favorably impact on OS in adjuvant setting. The conflicting results of randomized trials on adjuvant CRT in PDAC could be due to < 45 Gy dose generally used.

Nonmetastatic pancreatic cancer : Improved survival with chemoradiotherapy > 40 Gy after systemic treatment

Purpose

The role of radiotherapy (RT) for nonmetastatic pancreatic cancer is still a matter of debate since randomized control trials have shown inconsistent results. The current retrospective single-institution study includes both resected and unresected patients with nonmetastasized pancreatic cancer. The aim is to analyze overall survival (OS) after irradiation combined with induction chemotherapy.

Patients and methods

Of the 73 patients with nonmetastatic pancreatic cancer eligible for the present analysis, 42 (58%) patients had adjuvant chemoradiotherapy (CRT), while 31 (42%) received CRT as primary treatment. In all, 65 (89%) had chemotherapy at any time before, during, or after RT, and 39 (53%) received concomitant CRT. The median total dose was 50 Gy (range 12–77 Gy), while 61 (84%) patients received >40 Gy.

Results

With a median follow-up of 22 months (range 1.2–179.8 months), 14 (19%) are still alive and 59 (81%) of the patients have died, whereby 51 (70%) were cancer-related deaths. Median OS and the 2‑year survival rate were 22.9 months (1.2–179.8 months) and 44%, respectively. In addition, 61 (84%) patients treated with >40 Gy had a survival advantage (median OS 23.7 vs. 17.3 months, p = 0.026), as had patients with 4 months minimum of systemic treatment (median OS 27.5 vs. 14.3 months, p = 0.0004).

Conclusion

CRT with total doses >40 Gy after induction chemotherapy leads to improved OS in patients with nonmetastatic pancreatic cancer.

Electronic supplementary material

The online version of this article (10.1007/s00066-018-1281-7) contains supplementary material, which is available to authorized users.

ACR Appropriateness Criteria® Resectable Pancreatic Cancer

Management of resectable pancreatic adenocarcinoma continues to present a challenge due to a paucity of high-quality randomized studies. Administration of adjuvant chemotherapy is widely accepted due to the high risk of systemic spread associated with pancreatic adenocarcinoma, but the role of radiation therapy is less clear. This paper reviews literature associated with resectable pancreatic cancer to include prognostic factors to aid in the selection of patients appropriate for adjuvant therapies. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Patterns of radiotherapy practice for pancreatic cancer: Results of the Gastrointestinal Radiation Oncology Study Group multi-institutional survey

No information is currently available regarding pancreatic cancer (PC) pattern of care in Italy. In the present study, a nationwide survey using a questionnaire was performed to enquire the local standards for PC diagnosis and radiotherapy treatment. Fifty-seven percent of 140 Italian centres completed questionnaire. The main causes of no radiotherapy indication were poor general condition (45%) and lack of guidelines (25%). Physicians (38%) employed neoadjuvant therapy in locally advanced PC patients, while in other centres (62%) adjuvant chemoradiation was administered. Adjuvant gemcitabine-based chemotherapy was selected as the treatment of choice by 59% of centres. Patients were treated mostly with doses of 50-54.9 Gy on the tumour (or bed) plus lymph nodes. A 3D-CRT technique was used in 81.2% of centres, while IMRT and IGRT were available in 61.2 and 48.7% of cases, respectively. Extensive variation exists with regard to patterns of care for PC in Italy. Nevertheless, cooperative studies emerging from this survey appeared beneficial.

Neoadjuvant vs adjuvant therapy for resectable pancreatic cancer: the evolving role of radiation

A major challenge with pancreatic cancer management is in the discrimination of clearly resectable tumors from those that would likely be accompanied by a positive resection margin if upfront surgery was attempted. The standard of care for clearly resectable pancreatic cancer remains surgery followed by adjuvant therapy, but there is considerable controversy over whether such therapeutic adjuvant strategies should include radiotherapy. Furthermore, in a malignancy with such high rates of distant metastasis, investigators are now exploring the feasibility and outcomes of delivering therapy in the neoadjuvant setting, both for clearly resectable as well as borderline resectable tumors. In this review, we explore the current standard of care of upfront surgery for clearly resectable cancers followed by adjuvant therapy, focusing on the role of radiotherapy. We highlight the difficulties in interpreting a literature fraught with inconsistencies in how resectable vs borderline resectable cancers are defined and treated. Finally, we explore the role of neoadjuvant strategies in the modern era.

Adjuvant chemoradiation for pancreatic cancer: what does the evidence tell us?

The role of adjuvant chemoradiation (CRT) for pancreas cancer remains unclear. A handful of randomized trials conducted decades of ago ignited a debate that continues today about whether CRT improves survival after surgery. The many flaws in these trials are well described in the literature, which include the use of antiquated radiation delivery techniques and suboptimal doses. Recent prospective randomized data is lacking, and we eagerly await the results the ongoing Radiation Therapy Oncology Group (RTOG) 0848 trial that is evaluating the utility of high quality adjuvant CRT in resected pancreas cancer patients. Until the results of RTOG 0848 are available we should look to other studies from the modern era to guide adjuvant treatment recommendations. Here we review the current state of the art for adjuvant pancreas CRT with respect to patient selection, radiation techniques, radiation dose, and integration with novel systemic agents.

CHD7 expression predicts survival outcomes in patients with resected pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with poor outcomes with current therapies. Gemcitabine is the primary adjuvant drug used clinically, but its effectiveness is limited. In this study, our objective was to use a rationale-driven approach to identify novel biomarkers for outcome in patients with early-stage resected PDAC treated with adjuvant gemcitabine. Using a synthetic lethal screen in human PDAC cells, we identified 93 genes, including 55 genes linked to DNA damage responses (DDR), that demonstrated gemcitabine sensitization when silenced, including CHD7, which functions in chromatin remodeling. CHD7 depletion sensitized PDAC cells to gemcitabine and delayed their growth in tumor xenografts. Moreover, CHD7 silencing impaired ATR-dependent phosphorylation of CHK1 and increased DNA damage induced by gemcitabine. CHD7 was dysregulated, ranking above the 90th percentile in differential expression in a panel of PDAC clinical specimens, highlighting its potential as a biomarker. Immunohistochemical analysis of specimens from 59 patients with resected PDAC receiving adjuvant gemcitabine revealed that low CHD7 expression was associated with increased recurrence-free survival (RFS) and overall survival (OS), in univariate and multivariate analyses. Notably, CHD7 expression was not associated with RFS or OS for patients not receiving gemcitabine. Thus, low CHD7 expression was correlated selectively with gemcitabine sensitivity in this patient population. These results supported our rationale-driven strategy to exploit dysregulated DDR pathways in PDAC to identify genetic determinants of gemcitabine sensitivity, identifying CHD7 as a novel biomarker candidate to evaluate further for individualizing PDAC treatment.