Unfortunately, lymphoma (Hodgkin’s and Non-Hodgkin’s lymphoma) is still an incurable disease for many people and new and smart treatment techniques are needed to improve the prognosis of these patients. The goal of the research described in this dissertation was to find pre-existing medications used in other cancers, using a technique that allows to test the dependence on anti-apoptotic proteins (proteins important for the survival of cancer cells). This technique is called BH3 profiling. By applying this technique, it has been found that tamoxifen, an affordable, anti-hormone drug that has been used in breast cancer for more than 40 years, can kill lymph node cancer cells in laboratory experiments and in animal experimental models. If tamoxifen is combined with a drug that blocks anti-apoptotic proteins, the anticancer effect is enhanced. This has led to a clinical trial in patients with untreatable aggressive lymphoma. In addition to these important findings and applications, this thesis describes the efficacy of combinations of different drugs in lymphoma and whether these agents alter the dependence on these anti-apoptotic agents. This project was carried out through a KWF grant.