Atrophic Telogen Effluvium from Cytotoxic Drugs and a Randomized Controlled Trial to Investigate the Possible Protective Effect of Pretreatment with a Topical Vitamin D3 Analogue in Humans

In a 2005 study, researchers examined whether a topical vitamin D3 analogue, calcipotriol, could protect against hair loss in 24 breast cancer patients undergoing chemotherapy. The patients were randomized to receive either calcipotriol or a vehicle solution, starting 4 days before chemotherapy. Despite the treatment, the study found no significant difference in hair loss between the two groups. The researchers observed a specific pattern of hair loss, which they termed "atrophic telogen effluvium," characterized by a predominance of shed telogen hairs and a tapering of the proximal hair shaft. This pattern suggests that chemotherapy causes hair follicles to prematurely enter the telogen phase. The study concluded that topical calcipotriol does not offer a protective effect against chemotherapy-induced hair loss.