Pre-operative versus post-operative radiosurgery for brain metastasis: Effects on treatment volume and inter-observer variability

PURPOSE/OBJECTIVES

Compared to post-operative whole brain radiotherapy, resection cavity radiosurgery reduces impact on neuro-cognitive function and improves quality-of-life. However, coverage of the operative tract, in addition to tumour bed, may lead to large treatment volumes and inter-observer variability. We hypothesized that pre-operative radiosurgery reduces target volume size and inter-observer variability compared to post-operative radiosurgery.

MATERIALS/METHODS

We identified 10 consecutive patients, with solitary brain metastasis, treated with post-operative cavity radiosurgery.Pre- and post-operative axial T1 contrast MRI were co-registered with the planning CT scans. Three radiation oncologists independently contoured the target volumes on the pre- and post-operative imaging. A 2mm-PTV margin was utilized for both strategies and radiosurgery treatment plans were generated. The following parameters were evaluated in the 2 plans: Mean target volume (cc), 50% isodose volume (cc), Inter-observer variability (Jaccard Index JI) and Conformity Index (CI).

RESULTS

There was no significant difference in the mean target volume, nor 50% isodose volume, between pre- and post-operative strategies. (17.6 (95% CI 9.98 - 25.22) versus 19.4 (95% CI 10.11 - 28.69) cc, P=0.80; 61.7 (95% CI 38.4 - 85.0) vs 77.7 (95% CI 34.94 - 120.46) cc, P=0.65). There was significantly less inter-observer variability and improved conformity in the pre-operative group (Mean JI 0.84(95% CI 0.82 - 0.86) versus 0.70 (95% CI 0.62 - 0.78), P = 0.005; Mean CI 1.32 (95% CI 1.26 - 1.38) vs 1.45 (95% CI 1.36 - 1.54), P= 0.01). Planned subgroup analysis did not reveal any significant difference (between pre- vs post-op) in the mean volume of cystic versus non-cystic metastasis. Deep lesions (>2.5cm from dura) had a larger post-operative target volume (25.8 (95% CI 15.1 - 36.5) vs 12.3 (95% CI 6.54 - 18.06) cc, P=0.06) compared to superficial lesions.

CONCLUSION

Pre-operative radiosurgery has less inter-observer variability and improved plan conformity. However, there was no difference in mean target volume between the pre- versus post-operative radiation. Contouring guidelines, and peer review, may help to reduce inter-observer variability for cavity radiosurgery.

Randomized, double-blind, placebo-controlled phase II study of AMG 386 in combination with cisplatin and capecitabine (CX) in patients (pts) with metastatic gastroesophageal adenocarcinoma

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Background: AMG 386, a first-in-class investigational peptide-Fc fusion protein (peptibody), blocks angiogenesis via inhibiting the interaction between angiopoietins-1 and -2 and the Tie2 receptor. We evaluated the efficacy and tolerability of AMG 386 or placebo plus CX in the first-line treatment of metastatic gastroesophageal adenocarcinoma.

Methods: Pts with confirmed metastatic adenocarcinoma of the stomach, gastroesophageal junction or distal esophagus were randomized 1:1:1 to receive CX (cisplatin, 80 mg/m2 IV Q3W; capecitabine, 1,000 mg/m2 orally BID for 14 days Q3W) plus AMG 386 10 mg/kg (Arm A), 3 mg/kg (Arm B), or placebo (Arm C) IV QW. The primary endpoint was progression-free survival (PFS). Secondary endpoints included objective response rate (ORR; in pts with measurable disease), adverse events (AEs), and pharmacokinetics (PK).

Results: 171 pts were randomized (Arm A/B/C, n = 56/59/56). Efficacy results are summarized in the table. The incidence of grade ≥ 3 AEs in Arms A/B/C was 80/84/75%. Serious AEs occurred in 73/60/47% and serious AEs grade ≥ 3 in 66/60/43% of pts. AEs in Arms A/B/C included abdominal pain (30/40/17%; grade ≥ 3, 18/3/4%), peripheral edema (13/29/6%; grade ≥ 3, 0/2/0%), venous thromboembolic events (20/22/19%; grade ≥ 3, 20/19/17%), and pulmonary embolism (9/3/15%; grade ≥ 3, 9/2/13%). Median AMG 386 Cmax and Cmin values at steady state after CX coadministration were dose-proportional. Coadministration with CX did not markedly affect AMG 386 exposure.

Conclusions: In this study, AMG 386 plus CX did not significantly improve PFS or ORR over placebo plus CX in this patient population. The toxicity of the combination of AMG 386 plus CX, compared with placebo, was greater but manageable. No unexpected AEs occurred.

[Table: see text]

[Table: see text]

Vandetanib plus mFOLFOX6 in patients with advanced colorectal cancer (CRC): A randomized, double-blind, placebo-controlled phase II study

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Background: Vandetanib is a once-daily oral agent that selectively targets key signaling pathways in cancer by inhibiting VEGF, EGF and RET receptor tyrosine kinases. Methods: Eligible patients with advanced CRC and who had previously progressed after an irinotecan- and fluoropyrimidine-containing regimen were randomized 1:1:1 to receive once-daily oral vandetanib (100 or 300 mg) + modified FOLFOX6 (mFOLFOX6) or placebo + mFOLFOX6; mFOLFOX6 was given as standard 14-day treatment cycles (oxaliplatin 85 mg/m2 2-hr and leucovorin 400 mg/m2 2-hr i.v. infusions, followed by 5- fluorouracil [5-FU] 400 mg/mg2 i.v. bolus and 5-FU 2400 mg/m2 46-hr i.v. infusion). The primary objective was to compare the number of patients with a progression event on or before a mandatory tumor assessment visit at data cut-off (∼4 months after last patient randomized). A progression event was defined as the earliest of objective and/or clinical disease progression, or death from any cause. Results: Between March and November 2007, 104 patients (aged 32–81 years) were randomized to receive study treatment ( Table ). At data cut-off on 8 March 2008, there was a greater % of progression events in the vandetanib 100 mg arm compared with placebo (72% [n=23] versus 65% [n=24]; HR=1.21, 2-sided 80% CI 0.82–1.80; 2-sided P=0.53), and also in the vandetanib 300 mg arm compared with placebo (77% [n=27] versus 65% [n=24]; HR=1.41, 2-sided 80% CI 0.96–2.07; 2-sided P=0.25). All except one patient in each group experienced an adverse event (AE) during the study with diarrhea, nausea, thrombocytopenia, and peripheral sensory neuropathy the most commonly reported AEs ( Table ). Neutropenia was the only CTC grade 4 AE to occur in >1 patient in any group (n=2, vandetanib 100 mg arm; n=0, vandetanib 300 mg arm; n=3, placebo arm). Conclusions: In this study of patients with advanced, previously treated CRC, there was no efficacy benefit for vandetanib (100 or 300 mg) + mFOLFOX6 versus placebo + mFOLFOX6.

[Table: see text]

[Table: see text]

Cationic liposomal paclitaxel in combination with gemcitabine in patients with advanced pancreatic cancer: A phase II trial

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Background: EndoTAG-1 is a novel cationic liposomal formulation of paclitaxel being developed for the treatment of solid malignancies. It acts by targeting activated negatively charged endothelial cells of tumor blood vessels. We present safety and efficacy data of a randomized, controlled phase II trial in pancreatic cancer (PC). Methods: 200 patients with advanced PC were randomized to 1st line treatment with weekly gemcitabine (GEM: 1000 mg/m2) and twice weekly infusions of EndoTAG-1 (E) at 3 different dose levels (Elow: 11 mg/m2, Emed: 22 mg/m2, Ehigh: 44 mg/m2) or GEM monotherapy. Patients were treated for 7 weeks and followed up for overall survival (OS) for at least 1 year. After finishing study treatment, any anti-tumor therapy was allowed. A subgroup of patients had the option to receive repeated cycles of combination therapy in case of at least stable disease according to RECIST until disease progression. Results: Median OS was substantially higher in the GEM+Emed and GEM+ Ehigh groups than the GEM monotherapy group. Adjusted hazard ratios for OS were 0.72 (95% CI 0.46–1.13) and 0.67 (0.43–1.07). In patients receiving >1 treatment cycle, median OS was 11.5 months (GEM+Ehigh); in the GEM+Emed group 75% of patients were alive at 1 year. Treatment with EndoTAG-1 and gemcitabine was generally well tolerated. A trend for increasing adverse event frequency with EndoTAG-1 dose was observed for infusion-related reactions associated with chills and pyrexia, and thrombocytopenia. The overall frequency of serious adverse events in the GEM+E groups was low, the most frequent SAE being pyrexia in 4 (8%) patients in the GEM+Ehigh group. There was no indication for significant organ toxicity associated with EndoTAG-1, even in patients receiving multiple treatment cycles. Conclusions: This phase II trial indicates a considerable survival benefit for patients with advanced PC receiving EndoTAG-1 in combination with gemcitabine and a favourable safety profile warranting further development of EndoTAG-1 in this indication.

[Table: see text]

Irinotecan in combination with 5-fluorouracil and folinic acid or with cisplatin in patients with advanced gastric or esophageal-gastric junction adenocarcinoma: results of a randomized phase II study

BACKGROUND

To identify the most effective of two combinations, irinotecan/5-fluorouracil (5-FU)/folinic acid (FA) and irinotecan/cisplatin, in the treatment of advanced gastric cancer, for investigation in a phase III trial.

PATIENTS AND METHODS

Patients were randomized to receive irinotecan [80 mg/m2 intravenously (i.v.)], FA (500 mg/m2 i.v.) and a 22-h infusion of 5-FU (2000 mg/m2 i.v.), weekly for 6 weeks with a 1-week rest, or irinotecan (200 mg/m2 i.v.) and cisplatin (60 mg/m2 i.v.), on day 1 for 3 weeks.

RESULTS

A total of 115 patients were eligible for analysis in the per-protocol population. The overall response rate in the irinotecan/5-FU/FA arm (n=59) was 42.4%, with a complete response rate of 5.1%. Corresponding figures for the irinotecan/cisplatin arm (n=56) were 32.1% and 1.8%, respectively. The median time to progression was 6.5 months (irinotecan/5-FU/FA) and 4.2 months (irinotecan/cisplatin) (P < 0.0001), with median survival times of 10.7 and 6.9 months, respectively (P=0.0018). The major toxicity was grade 3/4 neutropenia, which was more pronounced with irinotecan/cisplatin than with irinotecan/5-FU/FA (65.7% versus 27%). Diarrhea was the main grade 3/4 non-hematological toxicity with both irinotecan/5-FU/FA (27.0%) and irinotecan/cisplatin (18.1%).

CONCLUSIONS

Both combinations were active, with acceptable safety profiles. Irinotecan/5-FU/FA was selected as the most effective combination for investigation in a phase III trial in advanced gastric cancer.

[Radiation sensitivity testing and late neurological complications following radiosurgery for AVM: the use of SF2 from fibroblasts as a predictive factor]

PURPOSE

To identify SF2 as a prognostic factor of late complications from radiosurgery in patients treated for AVM.

PATIENTS AND METHODS

Five patients with AVM treated in three canadian institutions and who suffered clinically significant neurological sequelaes secondary to radiosurgery were identified. Their fibroblasts were cultured and their radiation sensitivity tested to determine the SF2 for each patient.

RESULTS

Patients who developed a neurological complication from radionecrosis, secondary to radiosurgery had an SF2 different than the two control patients with AVM and no complications and also from a group of five cancer patients without late radiation complications (P = 0.005).

CONCLUSION

Radiosurgery is an elective procedure. The identification of a subgroup of patients who are radiosensitive and at a higher risk of radiation induced complications can allow the treatment team to reduce the risk of such complications. SF2 as a new predictive factor should be incorporated in predictive models of risk from treatment of AVM by radiosurgery. This work needs to be confirmed in a larger cohort of patients.

Treatment planning aids in prostate cancer: friend or foe?

BACKGROUND

Rectal barium is commonly used as a treatment planning aid for prostate cancer to delineate the anterior rectal wall. Previous research at the Ottawa Regional Cancer Centre demonstrated that retrograde urethrography results in a systematic shift of the prostate. We postulated that rectal barium could also cause prostate motion.

PURPOSE

The study was designed to evaluate the effects of rectal barium on prostate position.

METHODS AND MATERIALS

Thirty patients with cT1-T3 prostate cancer were evaluated. Three fiducial markers were placed in the prostate. During simulation, baseline posterior-anterior and lateral films were taken. Repeat films were taken after rectal barium opacification. The prostate position (identified by the fiducials) relative to bony landmarks was compared before and after rectal barium. Films were analyzed using PIPsPro software.

RESULTS

The rectal barium procedure resulted in a significant displacement of the prostate in the anterior and superior direction. The mean displacement of the prostate measured on the lateral films was 3.8 mm (SD: 4.4 mm) in the superior direction and 3.0 mm (SD: 3.1) in the anterior direction.

CONCLUSIONS

Rectal barium opacification results in a systematic shift of the prostate. This error could result in a geographic miss of the target; therefore, alternate methods of normal tissue definition should be used.

Severe normal tissue complication correlates with increased in vitro fibroblast radiosensitivity in radical prostate radiotherapy: a case report

The radiation responses of fibroblasts taken from four patients undergoing radiotherapy for prostate cancer were evaluated in vitro. One patient exhibited a severe normal tissue late reaction after radiotherapy, and the fibroblasts from this patient also showed increased radiosensitivity. The other three patients exhibited a normal clinical response, and their fibroblast response in vitro was also considered normal when compared with previously published data from our laboratory. When cells were allowed to repair potentially lethal damage (PLDR), the differences between cell lines were reduced; therefore, a deficiency in PLDR did not cause the differences in radiosensitivity. Fractionated radiation resulted in elevated survival due to repair of sublethal damage (SLDR), and the differences in radiosensitivity were increased. In addition, the survival curves displayed an upward bending nature, indicative of an adaptive response. Thus, adaptive response and ability to modify it may play an important role in fractionated radiotherapy. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 336-342 (2000).

A prospective comparison of three systems of patient immobilization for prostate radiotherapy

PURPOSE

The study compared the setup reliability of 3 patient immobilization systems, a rubber leg cushion, the alpha cradle, and the thermoplastic Hipfix device, in 77 patients with cT1-T3, N0, M0 prostate cancer receiving conformal radiotherapy.

METHODS AND MATERIALS

Port films were analyzed and compared to simulation films to estimate the setup errors in the three coordinate axes (anterior-posterior, cranial-caudal, medial-lateral). A total vector error was calculated from these shifts.

RESULTS

The Hipfix was found significantly superior to the other two devices in reducing mean setup errors in all axes (p < 0.005). The average field-positioning error with the Hipfix ranged from 1.9 mm to 2.6 mm for all axes, whereas the deviation for the other two systems ranged from 2.7 to 3. 4 mm. Errors greater than 10 mm were virtually eliminated with the Hipfix system. There was a reduction in the mean total vector error in the alpha cradle and Hipfix patient cohorts over time, reflecting improved efficacy as a result of experience.

CONCLUSION

There was a significant difference in the performance of each immobilization device. The Hipfix was consistently more reliable in reducing setup errors than the other devices.