Phase I/II Radiation Dose-Escalation Trial of Intensity Modulated Radiotherapy (IMRT) with Concurrent Fixed Dose-Rate Gemcitabine (FDR-G) for Unresectable Pancreatic Cancer

Comparison of four target volume definitions for pancreatic cancer. Guidelines for treatment of the lymphatics and the primary tumor

BACKGROUND AND PURPOSE

Target volume definitions for radiotherapy in pancreatic ductal adenocarcinoma (PDAC) vary substantially. Some groups aim to treat the primary tumor only, whereas others include elective lymph nodes (eLNs). eLNs close to the primary tumor are often included unintentionally within the treatment volume, depending on the respective treatment philosophies. We aimed to measure the percentages of anatomical coverage of eLNs by comparing four different contouring guidelines.

PATIENTS AND METHODS

Planning target volumes (PTVs) were contoured using planning computed tomography (CT) scans of 11 patients with PDAC based on the Oxford, RTOG (Radiation Therapy Oncology Group), Michigan, and SCALOP (Selective Chemoradiation in Advanced Localised Pancreatic Cancer trial) guidelines. Clinical target volumes (CTVs) included the peripancreatic, para-aortic, paracaval, celiac trunk, superior mesenteric, and portal vein lymph node areas. Volumetric comparisons of the coverage of all eLN regions were conducted to illustrate the differences between the four contouring strategies.

RESULTS

The PTV sizes of the RTOG and Oxford guidelines were comparable. The SCALOP and Michigan PTV sizes were similar to each other and significantly smaller than the RTOG and Oxford PTVs. A large variability of eLN coverage was found for the various subregions according to the respective contouring strategies.

CONCLUSION

This is the first study to directly compare the percentage of anatomical coverage of eLNs according to four PTVs in the same patient cohort. Potential practical consequences are discussed in detail.

Impact of omission of elective nodal irradiation on treatment outcomes in locally advanced pancreatic adenocarcinoma patients treated with definitive concurrent chemoradiotherapy

BACKGROUND

We evaluated influence of limited-field radiotherapy with no elective nodal irradiation (ENI) on outcomes and toxicity profile in patients with locally advanced pancreatic adenocarcinoma (LAPAC), treated with definitive concurrent chemoradiotherapy (C-CRT).

METHODS

Thirty-five patients with histological proof of LAPAC underwent 50.4Gy of C-CRT with 5-FU followed by maintenance gemcitabine. Target volume included primary tumor and lymph nodes that appeared to be involved on either contrast-enhanced computerized tomography or 18F-fluoro-deoxyglucose positron emission tomography.

RESULTS

No grade 4/5 acute/late toxicity was reported at median 15.7 months. Acute hematologic plus non-hematologic grade 3 toxicity was noted in 10 (28.6%) patients. At long-term, 2 patients (5.7%) experienced grade 3 gastric outlet obstructions at 8.7 and 10.9 months, respectively. No isolated regional relapses were noted. Median overall-survival (OS), progression-free survival (PFS), and locoregional-PFS (LRPFS) were 15.2, 9.1 and 7.3 months, respectively. Corresponding 1- and 2-year survival estimates were 60.0% and 20.0% for OS, 41.9% and 17.4% for LRPFS, and 34.0% and 12.7% for PFS, respectively.

CONCLUSIONS

Compared to ENI literature, first report of a limited-field C-CRT study carried out in Turkey showed that omission of ENI was relatively well tolerated without compromising survival and locoregional control rates in patients with LAPAC.