Medicine is not a pure science, and doctors are human. Although individual mistakes are inevitable and can even be enlightening, complacency remains unacceptable. Healthcare systems must minimise errors and should require an approach that is as evidence based as our approach to prescribing (and with an impact that is at least equivalent). In the case I describe here the “uncontroversial” progress in multidisciplinary working by the cancer team undermined, paradoxically, the traditional role of the lead clinician, allowing avoidable harm to the patient to occur without evoking concern.

A fully independent elderly woman presented with lithium toxicity early last year. Depression was her only recent illness. She was discharged after her lithium dosage was reduced, without specific assessment or follow-up for mild renal impairment (her creatinine concentration was 180 μmol/l).

She presented again two months later with a 5 cm lump in her breast. An outpatient …