Climate and permafrost effects on the chemistry and ecosystems of High Arctic Lakes.

Permafrost exerts an important control over hydrological processes in Arctic landscapes and lakes. Recent warming and summer precipitation has the potential to alter water availability and quality in this environment through thermal perturbation of near surface permafrost and increased mobility of previously frozen solutes to Arctic freshwaters. We present a unique thirteen-year record (2003-16) of the physiochemical properties of two High Arctic lakes and show that the concentration of major ions, especially SO42-, has rapidly increased up to 500% since 2008. This hydrochemical change has occurred synchronously in both lakes and ionic ratio changes in the lakes indicate that the source for the SO42- is compositionally similar to terrestrial sources arising from permafrost thaw. Record summer temperatures during this period (2003-16) following over 100 years of warming and summer precipitation in this polar desert environment provide likely mechanisms for this rapid chemical change. An abrupt limnological change is also reflected in the otolith chemistry and improved relative condition of resident Arctic char (Salvelinus alpinus) and increased diatom diversity point to a positive ecosystem response during the same period.

Preoperative hypofractionated radiotherapy in the treatment of localized soft tissue sarcomas.

BACKGROUND: The primary treatment of soft tissue sarcomas (STS) is a radical resection of the tumor with adjuvant radiotherapy. Conventional fractionation of preoperative radiotherapy is 50 Gy in fraction of 2 Gy a day. The purpose of the conducted study was to assess the efficacy and safety of hypofractionated radiotherapy in preoperative setting in STS patients. METHODS: 272 patients participated in this prospective study conducted from 2006 till 2011. Tumors were localized on the extremities or trunk wall. Median tumor size was 8.5 cm, 42% of the patients had tumor larger than 10 cm, whereas 170 patients (64.6%) had high grade (G3) tumors. 167 patients (61.4%) had primary tumors. Patients were treated with preoperative radiotherapy for five consecutive days in 5 Gy per fraction, with an immediate surgery. Median follow up is 35 months. RESULTS: 79 patients died at the time of the analysis, the 3-year overall survival was 72%. Local recurrences were observed in 19.1 % of the patients. Factors that had a significant adverse impact on local recurrence were tumor size of 10 cm or more and G3 grade. 114 patients (42%) had any kind of treatment toxicity, vast majority with tumors located on lower limbs. 7% (21) of the patients required surgery for treatment of the complications. CONCLUSION: In this non-selected group of locally advanced STS use of hypofractionated preoperative radiotherapy was associated with similar local control (81%) when compared to previously published studies. The early toxicity is tolerable, with small rate of late complications. Presented results warrant further evaluation.

The analysis of the outcomes and factors related to iliac-obturator involvement in cutaneous melanoma patients after lymph node dissection due to positive sentinel lymph node biopsy or clinically detected inguinal metastases.

BACKGROUND: We assessed clinical-pathological features and outcomes of cutaneous melanoma patients after ilio-inguinal lymph node dissection (LND) in relation to the presence of metastases in iliac-obturator nodes. METHODS: We analyzed 390 consecutive patients who underwent ilio-inguinal therapeutic LND [TLND] (237) due to clinical/cytologically detected metastases or after completion LND [CLND] (153) due to positive SLN biopsy (in one cancer centre 1994-2009). Median follow-up time was 60 months. RESULTS: The 5-year overall survival (OS) rate was 49% and median OS - 52 months in the entire group of patients. According to univariate analysis following factors had significant negative influence on OS: presence of metastases to iliac-obturator nodes (5-year OS for positive versus negative: 54.5% and 32%, respectively), macrometastases, higher Breslow thickness, ulceration, higher Clark level, male gender, number of metastatic lymph nodes, extracapsular extension, and, additionally in the CLND group - micrometastases size ≥ 0.1 mm according to the Rotterdam criteria and non-subcapsular location of micrometastases. Iliac-obturator involvement was also negative factor for OS in multivariate analysis. The presence of iliac-obturator nodal metastases correlated with the following factors: type of LND-CLND versus TLND (15% versus 27.5%) of iliac-obturator involvement, respectively), higher Breslow thickness, extracapsular extension of nodal metastases, male gender. We have not identified any metastases in iliac-obturator nodes in group of patients with micrometastases size ≤1.0 mm and primary tumour Breslow thickness <4.0 mm or no ulcerated primary tumours. CONCLUSIONS: Metastases to iliac-obturator nodes have additional negative prognostic value for melanoma patients with inguinal basin involvement. We are able to identify the subgroup of patients after positive SLN biopsy without metastases to iliac-obturator nodes, probably requiring only inguinal LND.

The clinical characteristics and the role of surgery and imatinib treatment in patients with liver metastases from c-Kit positive gastrointestinal stromal tumors (GIST).

The purpose of this study was to analyze the clinical features of the group of c-KIT positive GIST patients with liver metastases evaluated and treated in two referral institutions as well as to attempt to define the role of surgery in the management of GIST given the emergence to imatinib as an important part of treatment strategy in GIST patients. Between August 2001 and December 2002, 90 patients with c-KIT positive GIST were referred to our institutions. In 50 patients metastatic disease were disclosed. Of these, 35 patients (35/50; 70%) were rendered to have liver metastases and therefore offered imatinib or surgical therapy depend on CT assessment. The median follow-up of these 35 patients calculated from the time of first operation was 23 months (range 3-246 months). Male patients comprised the majority of patients (70%) with liver metastases. In 14 patients (40%) the metastases were confined only to the liver, in the others 21 patients (60%) the liver metastases were accompanied by intraperitoneal dissemination (17; 48.6%) or local recurrences (4; 11.4%). The period of time between the diagnosis of primary lesion and occurring liver metastases ranged from 0 to 164 months (median time of liver metastases presentation was 16 months for patients undergone primary curative surgery). The liver metastases were estimated as resectable in 3 cases (8.6%) and hepatic resection of all gross lesions was possible. Group of 32 patients with unresectable liver involvement was considered to treatment with imatinib. The median time of imatinib treatment for survivors is 7.5 months (range: 3.5-18.5 months). Twelve patients (37.5%) demonstrated partial response (PR) and 16 patients (50%) stable disease (SD) according to RECIST criteria. We did not observe any complete response (CR). At median follow-up 7 months, 32 of 35 patients (91.4%) were alive, 3 patients (8.6%)remained free of disease and 28 patients (87.5%) remained on imatinib treatment and have maintained disease although with partial response or stabilization only. Radical surgical resection remains the only possibility of cure for GIST patients because the complete response after imatinib therapy is restricted to a few patients only. However, despite the advanced metastatic disease, approximately 90% of patients are alive and continue imatinib treatment with median follow-up time more than 7 months. Surgery in combination with adjuvant imatinib treatment may result in improved survival with patients with advanced GIST.