cqvip:Background:Hair loss from cytotoxic drugs is classically ascribed to the loss of fractured hairs (anagen effluvium). Telogen hair loss has also been described but some authors have denied any effect on the hair cycle. There are conflicting reports on a protective effect of pretreatment with a vitamin D analogue on cytotoxic drug-induced hair loss in rodents. Objectives:To investigate the process of cytotoxic hair loss and any protective effect on the hair of pretreatment with topical calcipotriol. Methods Breast cancer patients who were about to receive cycles of chemotherapy with cyclophosphamide 600 mg m-2, methotrexate 40 mg m-2 and 5-fluorouracil 600 mg m-2 were recruited and randomized to receive calcipotriol scalp solution 50 μg mL-1 or vehicle. The solution was applied twice daily from 4 days prior to chemotherapy and continued for 14 days in each treatment cycle. Shed, plucked and cut hairs were sampled. Absolute shed rates, the proportion of major hair types, the presence of proximal hair shaft changes, regrowth (using the new anagen hair count) and hair density were assessed. Results:Ten patients receiving calcipotriol and 14 receiving vehicle completed three treatment cycles and nine from both groups completed six cycles. There was no detectable effect of calcipotriol on the proportion of patients experiencing minimal hair loss from chemotherapy, shed rates, plucked telogen and fractured hair counts, the morphology of shed and plucked hair, hair regrowth or hair density. Combining results of the treatment groups, there was a large variation in the impact of chemotherapy on hair loss, from total loss in five patients to no obvious loss in five. Excluding the latter, during chemotherapy shed telogen hairs (mean 81%of shed hairs) predominated over fractured (12%) and anagen hairs (6%) (P=0.0002). The major pathological change was proximal hair shaft tapering, baseline mean 3%of shed hairs rising to 48%(P=0.0005) during treatment, and there was a consequent decrease in normal telogen hairs, baseline mean 98%of all telogen hairs falling to 55%(P=0.0005) during treatment. The pathological tapered telogen hairs had normal or small, sometimes diminutive, bulbs. Fracturing of hairs with diminutive bulbs produced typical ‘exclamation mark’hairs. Conclusions:The cardinal effects of cytotoxic drugs found in this study were tapering of the proximal hair shaft and premature entry of the follicle into telogen, conflicting with the conventional view that affected hair follicles continue in anagen. There was a resulting effluvium of a mixture of tapering telogen hairs and fractured hairs. As entry into telogen is an integral part of the process, cytotoxic hair loss may be regarded as a variant of the conventional ‘telogen effluvium’and we propose the term ‘atrophic telogen effluvium’. There was no obvious protective effect on the hair loss of prior treatment with topical calcipotriol.
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