Impact of completeness of adjuvant gemcitabine, relapse pattern, and subsequent therapy on outcome of patients with resected pancreatic ductal adenocarcinoma - A pooled analysis of CONKO-001, CONKO-005, and CONKO-006 trials

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) represents one of the most fatal malignancies worldwide. It is suggested that survival in PDAC depends, among other things, on pattern of disease recurrence.

PATIENTS AND METHODS

We performed a pooled analysis of the adjuvant therapy studies CONKO-001, CONKO-005, and CONKO-006, including a total of 912 patients with regard to prognostic factors in patients with recurrent disease. Overall survival from disease recurrence (OS 2) and disease-free survival (DFS) from the day of surgery were expressed by Kaplan-Meier method and compared using log-rank testing and Cox regression.

RESULTS

Of 912 patients treated within the previously mentioned CONKO trials, we identified 689 patients with disease recurrence and defined site of relapse. In multivariable analysis, the presence of isolated pulmonary metastasis, low tumour grading, and low postoperative level of CA 19-9 remained significant factors for improved OS 2 and DFS. Furthermore, completeness of adjuvant gemcitabine-based treatment (OS 2: P = 0.006), number of relapse sites (OS 2: P = 0.015), and type of palliative first-line treatment (OS 2: P < 0.001) significantly affected overall survival after disease recurrence in PDAC.

CONCLUSIONS

Determining tumour subgroups using prognostic factors may be helpful to stratify PDAC patients for future clinical trials. In case of disease recurrence, the site of relapse may have a prognostic impact on subsequent survival. Further investigations are needed to identify differences in tumour biology, reflecting relapse patterns and the differing survival of PDAC patients.

Relapse patterns after low-dose-rate prostate brachytherapy

PURPOSE

When biochemical failure (BF) develops after low-dose-rate prostate brachytherapy, the relapse site is frequently not found. We set out to find whether prostate-specific membrane antigen positron emission tomography -CT (PSMA PET-CT) scanning has improved knowledge of relapse patterns.

METHODS AND MATERIALS

A database was analyzed, which contained information and long-term followup on 903 men who had an iodine-125 seed implant as monotherapy for early-stage prostate cancer. There was a total of 68 BFs.

RESULT

In 38 men developing BF before PSMA PET-CT scanning was available, the site of relapse was local in six, distant in twelve, and unknown in twenty. In 30 men developing BF more recently who had a PSMA PET-CT scan, the relapse site was demonstrated in all cases, and 19 (63%) men had relapsed at the prostate base. Radiation dosimetry of base relapses and paired controls demonstrated that implants routinely delivered a lower radiation dose to the base than to the rest of the prostate. Eight of seventeen cases found to have prostate relapse only underwent salvage prostatectomy.

CONCLUSION

PSMA PET-CT scanning is highly effective in demonstrating the relapse site(s) when BF develops after low-dose-rate prostate brachytherapy. Knowledge of the relapse site increases management options for men developing BF.

Relapse patterns after radiochemotherapy of glioblastoma with FET PET-guided boost irradiation and simulation to optimize radiation target volume

Background

O-(2-18 F-fluoroethyl)-L-tyrosine-(FET)-PET may be helpful to improve the definition of radiation target volumes in glioblastomas compared with MRI. We analyzed the relapse patterns in FET-PET after a FET- and MRI-based integrated-boost intensity-modulated radiotherapy (IMRT) of glioblastomas to perform an optimized target volume definition.

Methods

A relapse pattern analysis was performed in 13 glioblastoma patients treated with radiochemotherapy within a prospective phase-II-study between 2008 and 2009. Radiotherapy was performed as an integrated-boost intensity-modulated radiotherapy (IB-IMRT). The prescribed dose was 72 Gy for the boost target volume, based on baseline FET-PET (FET-1) and 60 Gy for the MRI-based (MRI-1) standard target volume. The single doses were 2.4 and 2.0 Gy, respectively. Location and volume of recurrent tumors in FET-2 and MRI-2 were analyzed related to initial tumor, detected in baseline FET-1. Variable target volumes were created theoretically based on FET-1 to optimally cover recurrent tumor.

Results

The tumor volume overlap in FET and MRI was poor both at baseline (median 12 %; range 0–32) and at time of recurrence (13 %; 0–100). Recurrent tumor volume in FET-2 was localized to 39 % (12–91) in the initial tumor volume (FET-1). Over the time a shrinking (mean 12 (5–26) ml) and shifting (mean 6 (1–10 mm) of the resection cavity was seen. A simulated target volume based on active tumor in FET-1 with an additional safety margin of 7 mm around the FET-1 volume covered recurrent FET tumor volume (FET-2) significantly better than a corresponding target volume based on contrast enhancement in MRI-1 with a same safety margin of 7 mm (100 % (54–100) versus 85 % (0–100); p < 0.01). A simulated planning target volume (PTV), based on FET-1 and additional 7 mm margin plus 5 mm margin for setup-uncertainties was significantly smaller than the conventional, MR-based PTV applied in this study (median 160 (112–297) ml versus 231 (117–386) ml, p < 0.001).

Conclusions

In this small study recurrent tumor volume in FET-PET (FET-2) overlapped only to one third with the boost target volume, based on FET-1. The shrinking and shifting of the resection cavity may have an influence considering the limited overlap of initial and relapse tumor volume. A simulated target volume, based on FET-1 with 7 mm margin covered 100 % of relapse volume in median and led to a significantly reduced PTV, compared to MRI-based PTVs. This approach may achieve similar therapeutic efficacy but lower side effects offering a broader window to intensify concomitant systemic treatment focusing distant failures.