Role of upfront surgery for recurrent gastrointestinal stromal tumours.

BACKGROUND: Gastrointestinal stromal tumours (GISTs), despite complete surgical cytoreduction, are associated with recurrence rates of up to 50% at 2 years. At recurrence, tyrosine kinase inhibitor (TKI) therapy is recommended, conferring a survival of up to 55 months. Several studies have shown that patients with TKI-responsive recurrent GIST benefit from surgery. However, no studies have compared upfront surgery versus TKI alone. METHODS: Data were retrospectively collected from patients with recurrent GIST treated at Singapore General Hospital and National Cancer Centre Singapore over a 12-year period. Our primary end points were disease-free and overall survival (OS). RESULTS: A total of 186 patients underwent curative surgery for GIST between January 2000 and June 2012. Fifty-six (30%) patients experienced recurrence, of which 30 (54%) had resectable recurrent disease. Twenty-four patients underwent upfront surgery for their recurrence while the remaining six patients opted for non-surgical management. The median OS for all patients with recurrent GIST was 5.3 years (95% confidence interval (CI) 3.2-8.4). It was not reached for patients who underwent curative surgery for their recurrence, and was 3.9 years (95% CI 2.4-7.0) for patients who had palliative TKI and conservative management. There were significant differences in OS and disease-specific survival between patients who underwent curative surgery for recurrence compared with those who had not. CONCLUSION: Our study shows that upfront surgery is a reasonable treatment strategy for selected patients with recurrent GIST.

Brain metastasis in sarcoma: Does metastasectomy or aggressive multi-disciplinary treatment improve survival outcomes.

AIM: Brain metastasis is rare in sarcoma. Prognostic factors, optimal management strategies and therapeutic outcomes of such patients are not well studied. We aimed to evaluate the incidence, clinical characteristics and treatment outcomes of parenchymal brain metastasis in sarcoma patients. METHODS: This is a single center retrospective analysis. Overall survival (OS) was calculated from the time of diagnosis of brain metastasis to time of death. RESULTS: Sixteen patients (2.1%) with complete electronic medical records treated at our institution from 2002 to 2010 were identified. Median age was 52 years; 88% had additional sites of metastases. Eight different subtypes of soft tissue and bone sarcoma were identified. Eighty-one percent of the patients developed metachronous brain metastasis at a median of 14 months after initial sarcoma diagnosis. Thirty-eight percent of patients had solitary brain metastasis and 44% underwent aggressive therapy for brain metastasis, defined as either surgical resection or multimodality treatment. The remaining 56% received conservative treatment (either whole brain radiation alone, chemotherapy alone or best supportive care). Median OS for the entire cohort was 3.5 months (95% CI 1.1-6.3 months). A trend toward improved OS was observed with an aggressive treatment approach, 3.7 months versus 1.2 months (P = 0.077) and the usage of chemotherapy (P = 0.071). CONCLUSION: Brain metastasis in sarcoma is rare, usually coexists with significant systemic disease and is associated with a grave prognosis. Use of chemotherapy and an aggressive treatment approach in well-selected patients may be associated with improved survival. Prospective studies are needed to confirm these findings.

Optimization of interactions between a cationic conjugated polymer and chromophore-labeled DNA for optical amplification of fluorescent sensors.

Cationic conjugated polymers (CCPs) have been widely utilized as signal amplifiers in biosensors to improve the detection sensitivity through fluorescence resonance energy transfer (FRET) from CCPs to dye-labeled probes or targets. This paper investigates the effect of sodium dodecyl sulfate (SDS) on energy transfer between a cationic polyfluoreneethynylene copolymer (P1) and Texas Red labeled single-stranded DNA (ssDNA-TR). The presence of SDS in solution affects both the optical properties of P1 and TR emission within P1/ssDNA-TR complexes, which provides basic information on the role of SDS in FRET between P1 and ssDNA-TR. Although the quantum yield of P1 decreases in the presence of low concentrations of SDS, the presence of SDS reduces TR fluorescence quenching within P1/ssDNA-TR complexes and increases the number of optically active polymer repeat units within the proximity of TR, which are beneficial to P1-sensitized TR emission. In the absence of SDS, FRET from P1 to ssDNA-TR provides a 2.6-fold enhancement in TR emission intensity as compared to that upon direct excitation of TR at 595 nm. At the optimum SDS concentration (5 microM), P1-sensitized TR signal output increases to 11.3-fold relative to direct excitation of TR. This study highlights the importance of modulation of the CCP/ssDNA-dye interaction in improving the signal output of dye-labeled DNA by CCP through FRET.