VMAT with a custom 3D bolus treated nasal BCC with low early toxicity

KEY POINTS

• Seven nonsurgical patients with histologically confirmed nasal basal cell carcinoma were treated with VMAT. Lesions involved the nose, nasal ala, dorsum, or bridge and ranged from 0.4 to 3.5 cm.
• Each patient received a customized 1-cm 3D-printed silicone bolus conforming to the nasal surface. Treatment used 6-MV VMAT with partial arcs plus a vertex arc, daily CBCT, a 1-cm CTV margin, and 5-mm PTV expansion.
• All patients completed 60 Gy in 30 daily 2-Gy fractions. Mean lens Dmax was only 3.97 Gy on the right and 3.68 Gy on the left, while mean eye Dmax was 19.5 and 20.4 Gy, respectively.
• In one anatomically complex patient, an illustrative electron comparison showed better homogeneity with VMAT. When the electron plan was renormalized to approach equivalent target coverage, its maximum dose reached 130% of prescription versus 111% with VMAT; this comparison was descriptive and did not model an internal eye shield.
• At a median follow-up of 13 months (range 3–23), no clinical recurrences were reported. Two particularly challenging cases—a large ulcerative lesion and deeply invasive recurrent disease—had complete clinical responses at 16 and 3 months, respectively.
• No patient experienced grade ≥3 acute skin toxicity. Five developed grade 1 pigmentation change, while no fibrosis, cartilage necrosis, or deformation of the native nasal contour was observed.
• The authors emphasize that this approach is most defensible when superficial RT or brachytherapy is unavailable or when highly curved, extensive, recurrent, or ulcerative lesions make electron treatment difficult; the series does not establish VMAT superiority.

CLINICAL TAKEAWAY

SOURCE

Advances in Radiation Oncology