Optimizing Palliative Focal Radiation Therapy Dose in Cutaneous T-Cell Lymphoma: How Low Can You Go?

PURPOSE: Primary cutaneous T-cell lymphomas (CTCLs) are radiosensitive tumors with variable and often relapsing courses. Local disease can be treated with low-dose focal palliative radiation therapy (RT), though little data supports the use of a specific dose. This study assesses clinical outcomes after focal RT to a total dose of 4 Gy, 8 Gy, or 12 Gy. METHODS AND MATERIALS: An International Review Board-approved, retrospective, single-institution study was performed of 225 lesions in 41 patients with primary CTCL treated with low-dose focal RT from 2015 to 2020. Patient, tumor, and treatment characteristics were reviewed. The primary outcome was freedom from treatment failure (FFTF), defined as time to requiring local retreatment, and secondary outcomes included response rates and toxicities. RESULTS: Of the 225 lesions, 90 received 4 Gy, 106 received 8 Gy, and 29 received 12 Gy. Lesions treated with 12 Gy (96%) or 8 Gy (92%) had a significantly higher 1-year FFTF compared with 4 Gy (77%) (P = .034). Overall response rate and complete response rate were not significantly different between different doses (P = .117), though there was a trend toward higher overall response rate at initial assessment with 8 Gy versus 4 Gy (91.5% vs 82.2%, P = .057). Toxicity was low, with 7.1% of lesions having grade 2 or higher radiation dermatitis. CONCLUSIONS: In primary CTCL lesions treated with focal palliative RT, a dose response was noted favoring 8 to 12 Gy, with 1-year FFTF rates over 90%. However, 4 Gy resulted in substantially better outcomes than previously reported, with 77% requiring no further treatment at 1 year and comparable response rates to higher doses. While our data substantiates 8 to 12 Gy as the standard of care, it also suggests that 4 Gy should be considered an acceptable alternative in situations with concern for radiation toxicities, such as with fragile or heavily pretreated skin.

Addition of Iodinated Contrast to Rectal Hydrogel Spacer to Facilitate MRI-Independent Target Delineation and Treatment Planning for Prostate Cancer.

PURPOSE: Hydrogel spacers reduce rectal dose toxicity during prostate cancer radiation therapy. Current products require magnetic resonance imaging (MRI) for visualization during treatment planning, but MRI incompatibility and cost have prompted alternatives using computed tomography (CT). This case series evaluates the addition of iodinated contrast to hydrogel as such an alternative. METHODS AND MATERIALS: Three patients underwent rectal hydrogel spacer placement with iodinated contrast modification. CT was performed within 1 hour of injection and again 1 week later. MRI was obtained at the time of the second CT. Hydrogel delineation was compared between CT and MRI and between paired CT scans. RESULTS: Spacer enhancement was visible on CT immediately after hydrogel placement (mean Hounsfield units, 122; range, 52-193) but not at the second CT 1 week later (mean Hounsfield units, 8; range, -8 to 29). Delineated spacer volume did not significantly differ between immediate postprocedure CT and MRI ≥1 week later in 2 patients (patient 1: 16.6 vs 15.5 cm3; patient 2: 12.6 vs 14.7 cm3; paired t-test, P = .81). CONCLUSIONS: CT visualization of rectal hydrogel admixed with contrast is feasible and allows delineation of interface with rectum/prostate.