Trichology to predict efficacy of scalp cooling: New pathologic insights besides encouraging clinical results.

12093 Background: Chemotherapy continues to be an essential element of tumour-specific systemic therapy. The associated hair loss impacts patients ‘quality of life in addition. Sensor-controlled scalp cooling has proven itself as a method of preventing alopecia. This study evaluates the grade of hair preservation as well as predictive factors, including (ultra)structural changes of the hair follicle during treatment, offering potential for enhanced therapeutic strategies. Methods: Scalp cooling, was evaluated in 81 patients (79 women, 2 men, median age 56 years) undergoing breast carcinoma treatment (4x EC 90/600 mg/m² BSA followed by 12x PAC w). Key outcomes included hair preservation (Hair Mass Index = HMI), avoidance of visible hair loss (HMI ≥ 50), and prevention of severe hair loss (all measured by Cross Section Trichometer). Parameters such as hair density (HMI), trichologic parameters like hair shaft and bulb diameter, anagen rate, shaft surface damage and melanosomes changes were measured through (ultrastructural) microscopy. Results: Over the half (53%) of patients avoided successfully noticeable hair loss (HMI post ≥ 50). Most important predictors of successful hair preservation in different analyses included lower post-therapeutic shaft surface damage (via scanning electron microscopy) (β = -.30, p = .034), larger pre-treatment shaft diameter (via light microscopy) (OR = 1.11, p = .011), and stable melanosome density (via transmission electron microscopy) (β = .35, p = .013). Higher anagen ratio (β = .30, p = 0.009) and larger hair shaft diameter (β = .29, p=0,023) plays a crucial role in hair prevention, considering only light-microspcopic parameters. Comorbidity (OR = 0.12, p = .024) and alopecia causing medication (e.g. antihypertensiva) (β = -.31, p = .017) led to increased hair loss. Patients with fewer hair loss over the course reported higher quality of life (r = .25, p = .042) and lower psychological burden (r = -.42, p 69), coupled with the absence of comorbidities and alopecia-inducing medications, substantially enhances the efficacy of scalp cooling, elevating the probability of preventing severe hair loss (HMI ≥ 50) by nearly sevenfold (OR = 6.98, CI95% 1.01;48.33. Conclusions: Scalp cooling proves effective in preventing visible hair loss in 53% of patients, with mini-organ (hair follicle) characteristics influencing outcomes. It does not only prevent hair loss but also enhances quality of life, underscoring the need for personalized approaches in managing chemotherapy-induced alopecia. The study confirms the method's safety and effectiveness without increasing scalp metastasis risk.