Surveillance imaging with FDG-PET/CT in the post-operative follow-up of stage 3 melanoma.

Background: As early detection of recurrent melanoma maximizes treatment options, patients usually undergo post-operative imaging surveillance, increasingly with FDG-PET/CT (PET). To assess this, we evaluated stage 3 melanoma patients who underwent prospectively applied and sub-stage-specific schedules of PET surveillance. Patients and methods: From 2009, patients with stage 3 melanoma routinely underwent PET +/- MRI brain scans via defined schedules based on sub-stage-specific relapse probabilities. Data were collected regarding patient characteristics and outcomes. Contingency analyses were carried out of imaging outcomes. Results: One hundred and seventy patients (stage 3A: 34; 3B: 93; 3C: 43) underwent radiological surveillance. Relapses were identified in 65 (38%) patients, of which 45 (69%) were asymptomatic. False-positive imaging findings occurred in 7%, and 6% had treatable second (non-melanoma) malignancies. Positive predictive values (PPV) of individual scans were 56%-83%. Negative scans had predictive values of 89%-96% for true non-recurrence [negative predictive values (NPV)] until the next scan. A negative PET at 18 months had NPVs of 80%-84% for true non-recurrence at any time in the 47-month (median) follow-up period. Sensitivity and specificity of the overall approach of sub-stage-specific PET surveillance were 70% and 87%, respectively. Of relapsed patients, 33 (52%) underwent potentially curative resection and 10 (16%) remained disease-free after 24 months (median). Conclusions: Application of sub-stage-specific PET in stage 3 melanoma enables asymptomatic detection of most recurrences, has high NPVs that may provide patient reassurance, and is associated with a high rate of detection of resectable and potentially curable disease at relapse.

Skull base meningioma - comparison of intensity-modulated radiotherapy planning techniques using the moduleaf micro-multileaf collimator and helical tomotherapy.

AIMS: Therapeutic radiotherapy to lesions of the skull base is limited by complex target shapes and their proximity to organs at risk. Intensity-modulated radiotherapy (IMRT) using helical tomotherapy may result in improved dose distributions and safer dose escalation. The aim of this study was to compare plan efficacy and efficiency using, linac-based micro-multileaf collimator (mMLC) IMRT and helical tomotherapy. MATERIALS AND METHODS: Five cases of skull base meningioma, previously treated with three-dimensional conformal radiotherapy (50 Gy/30 fractions) were identified. They were re-planned to a dose of 60 Gy/30 fractions using IMRT with Moduleaf mMLC (2.5 mm) and helical tomotherapy. Plan efficacy was compared using measures of PTV(60) coverage (D(min), D(max), V(90%), V(95%) and V(100%)). Plan efficiency was assessed by comparing estimated beam-on times. RESULTS: The critical structure dose was limited to below predetermined tolerance levels in all cases, with similar doses obtained between techniques. The average PTV(60)D(max), D(min), D(med), D(mean), V(90%), V(95%) and V(100%) across the five cases achieved were as follows: mMLC IMRT: 64.9 Gy, 40.1 Gy, 60 Gy, 59.6 Gy, 95.4%, 88.8% and 69.2%, respectively; helical tomotherapy: 67.2 Gy, 50.3 Gy, 60 Gy, 59.9 Gy, 95.8%, 83.5% and 51.9%, respectively. The average treatment time per fraction was 18.4 min for IMRT with mMLC and 6.7 min for helical tomotherapy. DISCUSSION: This study shows that safe dose escalation to a dose of 60G y to skull base lesions can be achieved; using either mMLC- or helical tomotherapy-based IMRT. A plan comparison between the two solutions is difficult, but they seem to be similar in efficacy with any small differences being difficult to interpret and of questionable clinical significance. Helical tomotherapy has the advantage of a significantly decreased beam-on time.

Intensity-modulated radiotherapy plan optimisation for skull base lesions: practical class solutions for dose escalation.

AIMS: To identify practical intensity-modulated radiotherapy planning solutions when attempting dose escalation in the skull base. MATERIALS AND METHODS: Twenty cases of skull base meningioma were re-planned using a variation of beam number (three, five, seven and nine), beam arrangement (coplanar vs non-coplanar) and multileaf collimator (MLC) width (2.5 mm vs 10 mm) to 60 Gy/30 fractions. Plan quality and planning target volume coverage was assessed using planning target volume V(95%), equivalent uniform dose (EUD) and integral dose. RESULTS: Critical structures were maintained below clinical tolerance levels. The 2.5 mm MLC achieved an average improvement in V(95%) by 22.8% (P=0.0003), EUD by 3.7 Gy (P=0.002) and reduced the integral dose by 13.4 Gy (P=0.0001). V(95%) and the integral dose improved with five vs three beams and seven vs five beams, but did not change with nine vs seven beams. There was no effect of beam number on EUD. There was no difference in V(95%) (P=0.54), integral dose (P=0.44) or EUD (P=0.47) for beam arrangement used. Segments per plan increased by a factor of 1.5 with each addition of two beams to a plan, and by a factor of 2.5 for 2.5 mm MLC plans vs 10 mm MLC plans. CONCLUSIONS: We present evidence-based planning solutions for skull base intensity-modulated radiotherapy, and show that 2.5 mm MLC and five to seven beams can achieve safe dose escalation up to 60 Gy. This must be balanced with an increase in segmentation, which will increase treatment times.

Pattern of relapse after fractionated external beam radiotherapy for meningioma: experience from Addenbrooke's Hospital.

AIMS: Radiotherapy is an important treatment modality for meningioma. We aimed to review the clinical outcomes for meningioma patients treated with radiotherapy in the Addenbrooke's Hospital Oncology Department. MATERIALS AND METHODS: A retrospective chart review was carried out on patients with meningioma referred and treated in the department between 1 November 1996 and 31 October 2006. Patient details and outcomes were recorded and the results were analysed to assess survival outcomes. Survival data were confirmed by the Eastern Cancer Registration and Information Centre. RESULTS: In total, 174 patients were referred to the department for an oncology opinion. Of these, 128 proceeded to radiotherapy. The median follow-up was 5.3 years (range 2.1-11.9 years). Sixty-seven per cent of the patients were older than 50 years, and the female: male ratio was 2.2: 1. Overall survival was 78% at the time of follow-up, with death related to meningioma in 7% of the total cohort. Local control was 85% overall, 93% for grade 1 disease, 45% for grade 2 disease and 82% for grade 3 disease. Patients with non-benign disease were more likely to receive >50Gy (27% of grade 1 lesions vs 65% of grade 2/3 lesions), but despite this local control remained poor, even with the higher dose delivered (local control 60 and 40% for grade 2 lesions treated with 50 and >50Gy, respectively, and 100 and 75% for grade 3 lesions treated with 50 and >50Gy, respectively). CONCLUSIONS: Our cohort of patients had an overall local control and survival similar to those documented from other departments. Grade was an important prognostic factor. Patients treated with >50Gy had worse local control outcomes, probably due to selection bias. Dose escalation may still be appropriate for high-risk disease, and may be more effective with more conformal techniques, such as intensity-modulated radiotherapy.