PO-0643: Scalp-sparing radiotherapy to minimize alopecia in patients with primary brain cancer

Purpose or Objective Radiotherapy may induce transient or permanent hair loss with a significant psychological impact on patient’s quality of life. Sparing the scalp during focal cranial RT for primary brain cancer is a challenging issue because the scalp is often adjacent to the target and because clear constraints for this structure are not available in the literature. Herein, we report ad-interim results of a prospective clinical study using a scalp sparing technique in primary brain cancer. Material and Methods Patients treated with focal radiotherapy for primary brain cancer were included. Factors that may have an impact on alopecia (age, cigarette smoking, use of levetiracetam and chemotherapy) were registered. During the simulation CT a wire was used to indicate the hairline of the patient (figure 1). During the contouring process, the scalp volume was defined as a ring region of interest including the tissue between the skin and the skull. For the inverse planning, primary constraint for the scalp was Dmax≤16 Gy, secondary constraint was Dmax≤25 Gy, tertiary constraint was Dmax≤35 Gy. VMAT plans were generated for a prescription dose of 50-60 Gy in 2-Gy daily fractions. Clinical evaluation was provided at the end of the radiation treatment for assessing the transient alopecia and every 6 months to evaluate the permanent hair loss. During each clinical follow-up evaluation, the patient was asked to wear the thermoplastic mask used during the treatment in order to define with a wire the area of alopecia (figure 2 and 3). Then, a CT scan was performed to the mask and these images are coregistered to the simulation CT to obtain a dosimetric evaluation in the areas of alopecia (figure 4). Alopecia was assessed according to CTCAE version 4.0. Results Meeting the constraints that we had set for the scalp was not always feasible for cortical and subcortical targets. Dose to the scalp was always minimized as much as possible. A total of sixty patients were enrolled. 46 patients were available for the evaluation of acute alopecia. Three out of 46 had no alopecia; G1 and G2 alopecia occurred in 7 and 36 patients, respectively. The risk of acute alopecia was proportional to the dose received by the scalp Dose to the scalp 10Gy 16Gy 20Gy 25Gy 30Gy 35Gy Risk of alopecia 7-31% 45-49% 47-65% 53-74% 55-77% 62-80% 14 patients performed the first trichological follow-up at 6 months: twelve out of 14 (85.7%) completely recovered their alopecia (4 had G1 alopecia, whereas 10 had G2 alopecia when they finished RT). Conclusion Our preliminary results show that risk of acute alopecia is proportional to the dose received by the scalp. Minimizing the dose to the scalp seems to lead a high probability of alopecia recovery after 6 months. These results need to be confirmed with the long-term follow up of all the enrolled patients. Study of the dose distribution in the areas of alopecia will be the base for the definition of reliable constraints both for transient and permanent alopecia.