The objective of this study was to evaluate the cost effectiveness of no prophylaxis, primary prophylaxis (PP), or secondary prophylaxis (SP) with granulocyte colony-stimulating factors (G-CSFs), i.e., pegfilgrastim, lipegfilgrastim, filgrastim (6- and 11-day), or lenograstim (6- and 11-day), to reduce the incidence of febrile neutropenia (FN) in patients with stage II breast cancer receiving TC (docetaxel, cyclophosphamide) and in patients with non-Hodgkin lymphoma (NHL) receiving R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) over a lifetime horizon from a Belgian payer perspective.