The purpose of this study was to perform an initial investigation of the possibility to determine breast cancer growth rate with C-14 bomb-pulse dating. Tissues from 11 breast cancers, diagnosed in 1983, were retrieved from a regional biobank. The estimated average age of the majority of the samples overlapped the year of collection (1983) within 3 sigma. Thus, this first study of tumour tissue has not yet demonstrated that C-14 bomb-pulse dating can obtain information on the growth of breast cancer. However, with further refinement, involving extraction of cell types and components, there is a possibility that fundamental knowledge of tumour biology might still be gained by the bomb-pulse technique. Additionally, delta C-13 and delta N-15 analyses were performed to obtain dietary and metabolic information, and to serve as a base for improvement of the age determination.