Malignant lymphoma is a general term for cancer of the lymphatic system. Malignant lymphomas refer to tumours that originate from one type of white blood cells – lymphocytes. They are manifested in particular by an increase in the size of the lymph nodes. The basic division classifies malignant lymphomas into two groups: Hodgkin’s lymphoma (HL) and non-Hodgkin’s lymphoma (NHL), which represents a significantly more heterogeneous group.
Malignant lymphomas are conditions which very often affect people at a young age. There are approximately 1,800 new cases per year in the Czech Republic. The prognosis of the disease is often very good.
The therapeutic procedure is established by a specialist – haematologist/oncologist. At present, promising treatment of malignant lymphomas is a systemic (whole-body) treatment represented by chemotherapy or biological treatment and/or a combination of both. Radiotherapy serves primarily as a complementary treatment designed to reduce the risk of disease recurrence in the originally affected areas, or as a curative treatment before the next planned systemic treatment, for example, in the case of relapsed lymphomas. It is a local treatment limited to a certain location or area of the body.
In this indication, radiotherapy is used for early and moderately advanced stages of Hodgkin’s lymphoma, high-risk non-Hodgkin’s lymphoma (affection with a large initial finding, affection of bones or finding outside the nodes) and in patients with an inadequate therapeutic response to a previous systemic therapy. Combined treatment (systemic treatment + radiotherapy) often means a higher chance of recovery from the lymphoma.
Due to the excellent efficacy of radiotherapy, it is not usually necessary to use radiation doses exceeding the tolerance limits for surrounding healthy tissues. Nonetheless, even lower radiation doses may be potentially harmful, in particular, in the time horizon of ten or more years after cancer therapy. This often occurs without any relation to the acute toxicity of radiotherapy. With a longer period of time elapsed after the completion of cancer therapy, the risk of development of late toxicity rises. Such risks should be considered especially in patients with a very good long-term prognosis. They include, in particular, young patients with Hodgkin’s lymphoma and B-cell non-Hodgkin’s lymphoma with favourable prognosis (mainly the subtypes, such as diffuse large B-cell lymphoma, primary mediastinal B-cell lymphoma). These patients should always be treated with awareness of the long-term risks of cancer treatment.
Irradiation may cause immediate adverse effects of radiation. They occur during RT and maximum up to 6 weeks after its completion.
Possible symptoms of acute radiation toxicity (related to the irradiated area) include:
Furthermore, in the context of RT, we can encounter late radiation sequelae which may occur even without prior difficulties within an interval of several decades after RT (most frequently after 10 years or more). In the treatment of lymphomas, it is vital, and physicians exert great effort to minimise such late sequelae and the risk of their occurrence. Possible symptoms of late toxicity depending on the location of the irradiated area:
Careful consideration of the irradiation indication is essential. The need to include RT in the treatment scheme is confirmed by clinical studies. In the Czech Republic, we follow the recommendations of the Czech Lymphoma Study Group (CLSG), which reflect the latest results of those clinical studies and are updated regularly. When carrying out RT, we also follow the recommendations of ILROG (International Lymphoma Radiation Oncology Group).
