Topical calcipotriol treatment in advanced breast cancer [published erratum appears in Lancet 1991 Jun 29;337(8757):1618] 19 patients with locally advanced or cutaneous metastatic breast cancer were treated with the topical vitamin D analogue calcipotriol 100 micrograms daily. 14 patients completed 6 weeks' treatment; 3 showed a 50% reduction in the bidimensional diameter of treated lesions and 1 other patient showed a minimal response. 2 patients became hypercalcaemic during treatment. In all patients who responded the tumours contained receptors for 1,25-dihydroxyvitamin D3, shown by immunocytochemistry. 