Sir, following on from the paper regarding novel chemotherapy (BDJ 2020; 228: 415-421) I would like to highlight a further category of targeted therapies. The Cyclin Dependent Kinases 4 and 6 (CDK 4/6) inhibitors disrupt cancer cell proliferation and are used in the management of previously untreated hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer. The drugs in this group include abemaciclib (Verzenios),1 palbociclib (Ibrance)2 and ribociclib (Kisqali)3 and are given alongside an aromatase inhibitor.

When planning invasive dental treatment it is important to liaise with the patient's oncology team as it is usually recommended the patient withholds the drug prior to dental treatment. These targeted therapies are given orally in a three week on one week off regime and therefore it is advisable to plan dental treatment in the off week and withhold the drug for at least seven days post-operatively. These drugs cause pancytopenia so haematological investigations including a full blood count should be carried out prior to any invasive dental treatment.