Background
Anal cancer
Prevalence and risk factors
Treatment
Multiparametric MRI
Diffusion Weighted MRI (DW-MRI)
Dynamic Contrast Enhanced MRI (dCE-MRI)
Rationale for the proposed study
Multiparametric MRI as a biomarker in anal cancer
Study hypothesis
Methods
Study design
Objectives
Primary study endpoint
Secondary study endpoint
Study schematic
Subject selection and withdrawal
Inclusion criteria
Exclusion criteria
Radiation therapy
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Intensity Modulated Radiation Therapy (IMRT)
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Volumetric Modulated Arc Therapy (VMAT)
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Tomotherapy
Target prescription dose
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The primary tumour PTV will receive 50.4 Gy in 28 fractions at 1.8 Gy per fraction
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The uninvolved nodal PTVs will receive 42 Gy in 28 fractions at 1.5 Gy per fraction
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The primary tumour PTV will receive 54 Gy in 30 fractions at 1.8 Gy per fraction.
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The uninvolved nodal PTVs will receive 45 Gy in 30 fractions at 1.5 Gy per fraction.
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The primary tumour PTV will receive 54 Gy in 30 fractions at 1.8 Gy per fraction.
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For involved nodes ≤ 3 cm in maximum dimension, the involved nodal PTV will receive 50.4 Gy in 30 fractions at 1.68 Gy per fraction.
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For involved nodes > 3 cm in maximum dimension, the involved nodal PTV will receive 54 Gy in 30 fractions at 1.80 Gy per fraction.
Dose specifications
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98% of the relevant PTV should receive >95% of the prescription dose
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No more than 2% of the relevant PTV should receive >107% of the prescription dose
Treatment schedule
Treatment planning
Dose constraints
ORGAN | CONSTRAINTS: No More than | ||
---|---|---|---|
Small Bowel
| 195 cc above 45 Gy | 1% of small bowel > 52 Gy | |
Femoral Head
| 50% above 30 Gy | 35% above 40 Gy | 5% above 44 Gy |
Iliac Crests
| 50% above 30 Gy | 35% above 40 Gy | 5% above 50 Gy |
External Genitalia
| 50% above 20 Gy | 35% above 30 Gy | 5% above 40 Gy |
Bladder
| 50% above 55 Gy | ||
Large Bowel
| 50% above 50 Gy |
Chemotherapy
5-Fluorouracil (5-FU)
Mitomycin-C
Pathology
Follow-up and surgery
Progressive disease
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Biopsy
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○ If negative, reassess in 4 weeks
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○ If positive and no evidence of distant disease, consideration of abdominoperineal resection (APR) is recommended
Persistent disease
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No biopsy, reassess in 4 weeks
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Patients with clinical suspicion of persistent disease at 26 weeks should undergo a biopsy and consideration of APR, if positive.
Complete clinical response
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No biopsy
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Continue to follow-up at the discretion of treating clinician
Imaging
Imaging schedule
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Prior to CRT
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During the second week of treatment (fraction days 6-10)
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During the fourth week of treatment (fraction days 16-20)
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At 6-8 weeks post treatment
Imaging process
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Performed at 4 b-values
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○ 0, 400, 800 and 1200
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Contrast injection:
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○ Magnevist 0.2 ml/kg
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○ Power Injector (2.5 ml/s)
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○ 20 ml saline chase at same rate as injection
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Imaging analysis
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A ROI will be placed over the entire primary and involved nodal regions to calculate mean and median primary and nodal Ktrans and Kep values and Relative Signal Intensity (RSI) (Figure 2)×
Statistical considerations
Sample size determination
Definition of complete response
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No evidence of residual tumour at 26 weeks post CRT
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No progression requiring APR prior to 26 weeks