Adjuvant radiotherapy for atypical and malignant meningiomas: a systematic review

Atypical meningiomas (AMs) and malignant meningiomas (MMs) are tumors with a lower incidence and poorer prognosis than benign meningiomas. The role of radiotherapy as an adjuvant to surgical resection, especially for AMs, is incompletely defined. In this study, the English-language literature was systematically reviewed for studies that reported tumor characteristics, treatment parameters, and clinical outcomes after adjuvant radiotherapy for AM and MM, including overall survival, progression-free survival, and/or time to recurrence or mortality. Clinical outcomes were further assessed in the context of resection status, timing of administration, and radiation dose. Outcomes after stereotactic radiosurgery were also examined. Treatment toxicity and other potential prognostic or confounding factors were appraised. Ten and 11 studies for AM and MM, respectively, met the inclusion criteria. The median 5-year progression-free survival and overall survival after adjuvant radiotherapy were 54.2% and 67.5%, respectively, for AM and 48% and 55.6% for MM. The complication rates were 11.1% for AM and 5.1% for MM. Incomplete resection and radiation dose <50 Gy conferred significantly poorer 5-year progression-free survival. Most studies were unable to demonstrate a statistically significant prognostic benefit for adjuvant radiotherapy in AM. In conclusion, adjuvant radiotherapy significantly improved local control of AMs and MMs, especially after subtotal resection. Study limitations, including inadequate statistical power, may underlie the studies'' inability to demonstrate a statistically significant benefit for adjuvant radiotherapy in AM. Because these tumors preferentially recur within 5 years of surgical resection, future studies should define whether early adjuvant therapy should become part of the standard treatment paradigm for completely excised tumors.     

HPLC analysis of some allowable-antibiotic multiresidues in farmed rainbow trout in Iran

This study aimed to investigate the occurrence of antibiotic residues in rainbow trout muscle samples (n?=?74) obtained from Iranian trout farms. The levels of the antibiotics were determined by in-house validated HPLC methods. Oxytetracycline, tetracycline, enrofloxacin, ciprofloxacin, and florfenicol residues were detected in 6.76%, 37.8%, 31.1%, 10.8%, and 14.9% of the samples, respectively; while chlortetracycline was not detected. The detected range of concentrations for positive samples was 8.94–81.2 μg/kg for oxytetracycline, 7.99–98.4 μg/kg for tetracycline, 6.75–87.4 μg/kg for enrofloxacin, 5.83–11.5 μg/kg for ciprofloxacin, and 49.9–313.6 μg/kg for florfenicol. None of the samples exceeded the maximum residue levels (MRLs) established by the Institute of Standards and Industrial Research of Iran. The co-occurrence of antibiotics was detected in 40.5% of the analyzed samples. The frequency of co-occurrence of enrofloxacin-tetracycline was the highest (16.2%). Despite the fact that concentrations of the analyzed antibiotics in trout samples did not exceed the MRLs, their co-occurrence in such a level could be a serious public health problem.     

Does delaying surgery in immature adolescent idiopathic scoliosis patients with progressive curve,lead to addition of fusion levels?

Purpose

To analyze the changes in the curve extent, pattern and the fusion level in adolescent idiopathic scoliosis (AIS) patients who undergo delayed surgery instead of early surgery.

Methods

Thirty-five immature AIS patients whose radiographs demonstrated an initial primary curve of more than 40° with a subsequent increase of 10° before attaining skeletal maturity with brace were enrolled. The initial and the final radiographs taken before surgery were compared to assess the changes in curve extent, pattern and the fusion levels as recommended by King’s, Lenke’s and Suk’s guidelines.

Results

The average age of 35 AIS patients was 12.7 ± 1.6 years. The time interval between initial and final radiography was 39.3 ± 20.2 months and the degree of progress of the primary curve was 13 ± 9.7°. Fusion levels changed in 33 (94.2 %), 33 (94.2 %) and 32 (91.4 %) patients according to King’s, Lenke’s and Suk’s guidelines, respectively. Curve pattern was changed in 2 (5.7 %), 12 (34.3 %) and 10 (28.6) patients by King’s, Lenke’s and Suk’s guidelines. The mean number of levels requiring fusion increased from 9.4 ± 2.1 at initial visit to 11.1 ± 1.8 at the final follow-up using King’s guidelines, 9.7 ± 2.2–11.6 ± 2.0 as per Lenke’s guidelines and 9.1 ± 2.0–11.5 ± 2.3 when fusion was planned using Suk’s guidelines (p < 0.001 in all guidelines).

Conclusions

Delay of surgery in immature AIS patients whose Cobb’s angle exceed 40° initially and showing subsequent progression of the curve, of more than 10° can lead to alterations in the curve pattern and the need for increase in fusion levels.     

Mechanics of longitudinal cracks in tooth enamel

A study is made of longitudinal "channel" cracking in tooth enamel from axial compressive loading. The cracks simulate those generated in the molar and premolar teeth of humans and animals by natural tooth function. Contact loading tests are made on extracted human molars with hard and soft indenting plates to determine the evolution of such cracks with increasing load. Fracture is largely stable, with initial slow growth followed by acceleration as the cracks approach completion around an enamel side wall. A simple power law relation expresses the critical load for full fracture in terms of characteristic tooth dimensions-base radius and enamel thickness-as well as enamel toughness. Extended three-dimensional finite element modeling with provision for growth of embedded cracks is used to validate this relation. The cracks leave "fingerprints" that offer valuable clues to dietary habits, and provide a basis for a priori prediction of bite forces for different animals from measured tooth dimensions.     

Stereotactic radiosurgery for benign meningiomas

Meningiomas are the second most common primary tumor of the brain. Surgical resection is the preferred treatment for easily accessible tumors that can be safely removed. However, many tumors arise deep within the skull base making complete surgical resection difficult or impossible. Stereotactic radiosurgery is a highly effective alternative to surgical resection that has been used as a primary therapy for benign meningiomas as well as an adjuvant treatment for residual or recurrent tumors. The 5-year tumor control rates for stereotactic radiosurgery are equivalent to gross-total resection with lower morbidity than surgery, especially for skull base lesions. Additionally, adjuvant treatment of subtotally resected tumors results in tumor control rates equivalent to gross-total resection. Stereotactic radiosurgery has been used extensively for the treatment of small and medium sized skull base meningiomas. This technique has also been applied to large meningiomas and superficial tumors such as convexity and parasagittal meningiomas. However, multiple studies demonstrate that tumor control is decreased for superficial lesions and with increasing tumor size. In addition, radiation toxicity increases with increasing tumor size and superficial location. Based on a thorough review of the literature, stereotactic radiosurgery should be considered the primary treatment for skull base meningiomas with high surgical risk and in cases of superficial meningiomas where surgery is contraindicated.     

Supratentorial hemangioblastoma: clinical features, prognosis, and predictive value of location for von Hippel-Lindau disease

Supratentorial hemangioblastoma is a rare form of hemangioblastoma; little information is available regarding prognosis, treatment, and clinical characteristics, because the available literature is primarily composed of case reports and small case series. Therefore, we performed a systematic review of the literature to analyze clinical characteristics, disease progression, and surgical outcomes with respect to survival for supratentorial hemangioblastomas. The rate of progression-free survival (PFS) was determined using Kaplan-Meier analysis. Differences in categorical factors, including location of tumor and diagnosis of von Hippel-Lindau (VHL) disease, were analyzed using the Pearson χ(2) test. A total of 106 articles met the search criteria, which combined for a total of 132 patients. Of the patients with supratentorial tumors, 60% had VHL disease, and 31 (84%) of 37 patients with tumors in the sellar/suprasellar region had associated VHL (χ(2), P < .001). Five-year PFS for gross-total resection and subtotal resection were 100% and 53%, respectively (Log rank, P < .01). On the basis of our analysis of the literature on published cases of supratentorial hemangioblastoma, gross-total resection appears to be superior to other treatment modalities in extending PFS. Von Hippel-Lindau disease is positively correlated with supratentorial hemangioblastoma when compared with non-supratentorial CNS hemangioblastomas, particularly when present in the sellar/suprasellar region.     

Comparison between prone and supine patient setup for spine stereotactic body radiosurgery

This paper investigates the dosimetric characteristics of stereotactic body radiotherapy (SBRT) treatment plans of spine patients in the prone position compared to the supine position. A feasibility study for treating spine patients in the prone position using a fiducial-less tracking method is presented. One patient with a multilevel spinal metastasis was simulated for SBRT treatment in both the supine and prone position. CT scans of the patient were acquired, and treatment plans were created using the CyberKnife? planning platform. The potential advantage of the prone setup as a function of lesion location and number of vertebral bodies involved was studied for targets extending over 1, 2 and 3 consecutive vertebral bodies in the thoracic and lumbar spine. The same process was repeated on an anthropomorphic phantom. A dose of 30 Gy in 5 fractions was prescribed to 95% of the tumor volume and the dose to the cord was limited to 25 Gy. To investigate the feasibility of a fiducial-less tracking method in the prone setup, the patient was positioned prone on the treatment table and the spine motion was monitored as a function of time. Patient movement with the respiratory cycle was reduced by means of a belly-board. Plans in the prone and supine position achieved similar tumor coverage and sparing of the critical structures immediately adjacent to the spine (such as cord and esophagus). However, the prone plans systematically resulted in a lower dose to the normal structures located in the anterior part of the body (such as heart for thoracic cases; stomach, lower gastrointestinal tract and liver for lumbar cases). In addition, prone plans resulted in a lower number of monitor units compared to supine plans.