[Non-hodgkin's lymphomas]

Abstract

With approximately 10000 cases per year in France, non-Hodgkin's lymphoma (NHL) represents the most frequent hematological malignancy, and 5 to 10 % of new cases of cancers. NHLs constitute a heterogeneous group of lymphoproliferative diseases, including entities with very different epidemiological and evolutive characteristics, as well as prognosis and treatments. Several classifications exist, but in practice, we individualize aggressive NHL including Diffuse Large B-Cell Lymphomas (DLBCL) which is the most common lymphoma, and indolent NHL including follicular lymphomas and mucosa-associated lymphoid tissue (MALT) lymphomas. The role of the radiotherapy in the management of NHLs varies according to the specific sub-type of lymphoma, but it has become increasingly limited over time. Overall it finds indications with curative intent only in situations of localized LMNH: either associated with chemotherapy as part of a combined modality therapy as for the treatment of localized DLBCL, or as exclusive treatment specially in the rare situations of localized follicular lymphomas. Moreover, lymphocytes being extremely radiosensitive cells, radiotherapy retains excellent indications with palliative intent for the management of symptomatic bulky tumor masses, and that whatever the sub-type of NHLs may be. It is important to remember that even today the "Involved Field" irradiation type remains the gold standard for the treatment of nodal NHLs, even if we witness at present the emergence of new types of irradiation, which aim to reduce the amount of irradiated tissues to try to limit the risks of delayed radio-induced complications. The purpose of this article is to clarify the specific aspects (epidemiological, radio-anatomical and prognostic characteristics) of each NHLs'sub-types (except primary central nervous system lymphomas), as well as the practical modalities of the irradiation (illustrated by a clinical case record) when an indication of radiotherapy is placed for their treatment.