Age-based reduction of chemotherapy dose with the first cycle (primary dose reduction, PDR) is not routinely guideline recommended. Few studies, however, have evaluated how frequently PDR is utilized in the treatment of older patients with cancer and which factors may be associated with this decision.We conducted a secondary analysis of a multi-institutional prospective cohort study of patients age ≥65 years treated with chemotherapy. The dose and regimen were at the discretion of the treating oncologist. The prevalence of PDR and its association with treatment intent (palliative vs. curative), tumor type, patient characteristics (sociodemographics and geriatric assessment variables), and chemotherapy-associated toxicity were evaluated.Among 500 patients (mean age 73, range 65-91 years), 179 patients received curative intent chemotherapy and 321 patients received palliative intent chemotherapy, with PDR being more common in the latter sub-group (15% vs. 25%, p = 0.005). Increasing age was independently associated with PDR in both sub-groups. Comorbidity (prior cancer or liver/kidney disease) was independently associated with PDR in the palliative sub-group alone while Karnofsky Performance Status (KPS) was not associated with PDR in either subgroup. There was no significant difference in the rates of grades 3-5 toxicity, dose reductions, or delays with PDR. Patients in the palliative sub-group treated with PDR had higher rates of hospitalization compared to those treated with standard doses.PDR is more common in the palliative setting, but is also utilized among patients treated with curative intent. Factors associated with PDR include age and comorbid conditions, but not KPS.
