Reproducibility of rectal tumor volume delineation using diffusion-weighted MRI: Agreement on volumes between observers.

PURPOSE: To retrospectively evaluate the inter-observer agreement between a radiologist and a radiation oncologist and volume differences, in T2 and diffusion-weighted (DWI) MRI of gross tumor volume (GTV) delineation, in rectal cancer patients. MATERIALS AND METHODS: Two observers, a radiologist and a radiation oncologist, delineated GTVs of 50 patients on T2-weighted MRI (T2GTV) and echo planar DWI (DWIGTV). Observers agreement was assessed using DICE index, Bland-Altman analysis and intra-class correlation coefficient (ICC). Student's t-test was used for GTV comparison. RESULTS: Median T2GTV and DWIGTV were 17.09±14.12 cm3 (1.92-62.03) and 12.79±12.31 cm3 (1.23-62.25) for radiologist, and 16.82±13.66 cm3 (1.78-65.9) and 13.72±12.77 cm3 (1.29-69.75) for radiation oncologist. T2GTV were significantly larger compared to DWIGTV (P<0.001 and P<0.001, for both observers). Mean DICE index for T2GTV and DWIGTV were 0.80±0.07 and 0.77±0.06. The mean difference between the two observers were 0.26cm3 (95% CI: -5.36 to 5.88) and -1.13cm3 (95% CI: -5.70 to 3.44) for T2 and DWI volumes. The ICC for T2 volumes was 0.989 (95% CI: 0.981-0.994) (P<0.001) and 0.992 (95% CI: 0.986-0.996) (P<0.001) for DWI volumes. CONCLUSION: DWI resulted in smaller volumes delineation compared to T2-weighted MRI. Substantial and almost perfect agreements were reported for DWIGTV and T2GTV between radiologist and radiation oncologist. Due to the fact that DWI could be considered a simple technique for volume delineation for radiation oncologist, DWI could be used to improve quality in radiation planning for an accurate boost volume delineation when a dose escalation is investigated.

Hippocampal sparing in stereotactic radiotherapy for brain metastases: To contour or not contour the hippocampus?

PURPOSE: The aim of our study was to evaluate hippocampal irradiation in patients treated with fractionated stereotactic brain radiotherapy. PATIENTS AND METHODS: Retrospective hippocampal dosimetric analysis performed on 22 patients with one to four brain metastases treated with fractionated stereotactic radiotherapy using volumetric intensity-modulated arc therapy. Original plans did not include hippocampus as avoidance structure in optimization criteria; hippocampus was retrospectively delineated on magnetic resonance coregistered with planning CT and using as reference the RTOG 0933 atlas. Hippocampus was defined both as a single and as pair organ. Constraints analysed were: Dmax<16Gy, D40%<7.3Gy, D100%=Dmin<9Gy. Assuming a α/ß ratio of 2Gy, biologically equivalent dose in 2Gy fractions was calculated. Hippocampal-sparing plans were developed in cases where hippocampal constraints were not respected in the original plan. RESULTS: Among constraints analysed Dmax and D40% have been exceeded in ten out of 22 cases. The constraints were not respected in patients with more than one metastatic lesion and in three patients with only one lesion. Considering all exceeded constraints values in non-hippocampal sparing plans, the 50% of them was respected after replanning. No significant differences were found among conformity and homogeneity index between non-hippocampal sparing and hippocampal sparing plans. CONCLUSION: Volumetric intensity-modulated arc therapy hippocampal sparing plans significantly decreases dose to hippocampus assuring an equal target coverage and organs at risk avoiding.

Interobserver variability of clinical target volume delineation in soft-tissue sarcomas.

PURPOSE: The present observational study reports the results of a multi-institutional dummy-run designed to estimate the consistency of interobserver variability in clinical target volume delineation in two different cases of soft-tissue sarcomas in which postoperative and preoperative radiotherapy were prescribed, respectively. The purpose of this work was to quantify interobserver variability in routine clinical practice. PATIENTS AND METHODS: Two different cases of soft-tissues sarcomas were chosen: a case of postoperative and a case of preoperative radiation therapy. Participating centres were requested to delineate clinical target volumes according to their experience in both cases. Descriptive statistic was calculated for each variable (volume, diameters) separately for two cases. Box-whiskers plots were used for presentation of clinical target volume. A Shapiro-Wilk's test was performed to evaluate the departures from normality distribution for each variable. The comparison between relative variations of diameters was evaluated using the Student's t test. RESULTS: Several variations affecting both volumes and diameters were observed. Main variations were observed in the craniocaudal and laterolateral diameters. Each case showed similar dispersion, indicating a lack of reproducibility in volumes definition. CONCLUSIONS: This observational study highlighted that, in the absence of specific instructions or guidelines, the interobserver variability can be significant both in postoperative and preoperative radiotherapy of soft-tissue sarcomas.

Tyrosine kinase inhibitors.

Over the last ten years, several new and therapeutically relevant cancer drugs targeting tyrosine kinases signaling pathways have been developed. Tyrosine kinase inhibitors (TKIs) are a pharmaceutical class of small molecules, orally available, well-tolerated, worldwide approved drugs for the treatment of several neoplasms, including lung, breast, kidney and pancreatic cancer as well as gastro-intestinal stromal tumors and chronic myeloid leukemia. This comprehensive review focuses on the most relevant members of the first and the second generation TKIs designed to interact with receptor and nonreceptor TKs. Attention is mainly focused on molecular mechanisms in in vitro and in vivo models related to the clinical activity of the drugs and to the development of resistance to treatment, still the major challenge in cancer research and care.

Early prognostic assessment of acute pancreatitis with sterile necrosis. A perspective clinical study.

In an attempt to early assess the prognosis of acute pancreatitis with sterile necrosis, we have perspectively studied 40 patients with necrotizing acute pancreatitis and sterile necrosis in the first 48 hours of disease. As prognostic parameters, we have considered the computed tomography score according to Balthazar, simplified prognostic criteria according to Agarwal, Glasgow criteria and C reactive protein. Patients were divided in A group, 5 patients who died, and B group, 35 patients who survived. Computed tomography score, simplified prognostic criteria and Glasgow criteria were significantly higher in A group than B (9.5 +/- 1 vs 6.3 +/- 1.9, 3.6 +/- 0.5 vs 1.2 +/- 1.2 and 5.4 +/- 1.7 vs 2.7 +/- 1.9 respectively); conversely, C reactive protein serum levels did not show significantly difference in the two groups. We conclude that the extension of pancreatic and extrapancreatic necrosis, as measured by computed tomography, as well as the failure of extrapancreatic organs and the development of systemic and metabolic complications, as assessed by simplified prognostic score and Glasgow criteria, are the most important determinant of prognosis in necrotizing acute pancreatitis with sterile necrosis.