Lymphoma is a group of cancers that affect the immune system. Lymphomas fall into one of two major categories: Hodgkin’s lymphoma (HL, previously called Hodgkin’s disease) and all other lymphomas (non-Hodgkin’s lymphomas or NHLs). These two types develop in different ways and from different types of cells, however they occur in the same places and can display the same symptoms. HL is most common in young adults.
Since the late 1970’s, non-Hodgkin lymphoma incidence rates have more than doubled (160% increase) in Great Britain. The incidence rate for Hodgkin’s lymphoma has not increased so rapidly in the same time period, at only 7%.
Risk factors for HL and NHL are mainly different, with 45% of HL cases each year in the UK linked to major lifestyle and other risk factors, while only 6% of NHL cases have this link.
Risk factors for Hodgkin lymphoma:
- Epstein-Barr virus is linked to an estimated 45% of Hodgkin lymphoma cases in the UK
- Human immunodeficiency virus (HIV) causes Hodgkin lymphoma
- Problems with the immune system, overweight and obesity, and smoking may relate to higher Hodgkin lymphoma risk
Risk factors for non-Hodgkin’s lymphoma:
- An estimated 4% of NHL cases in the UK are linked to infections (mainly H. pylori)
- Certain occupational exposures and medications cause NHL
- Ionising radiation, problems with the immune system, and overweight and obesity (for some NHL types) may relate to higher NHL risk
Symptoms for both types of lymphoma can vary depending on where it is in the body. Some common symptoms are:
- Lump(s) under the skin
- Night sweats
- Unexplained weight loss
- Feeling tired
- Cough, chest pain, trouble breathing
- Swollen abdomen
There are many different tests to diagnose lymphomas, usually a combination of techniques will be used. This can include a biopsy, blood tests, and imaging tests such as an x-ray, bone, CT, MRI or PET scan, or an ultrasound.
The usual treatment options for lymphoma are chemotherapy, photon or proton radiotherapy, and biologic therapy (which boosts the immune system). Sometimes some stem cells will be taken before chemotherapy and transplanted back into the body to help build healthy new blood cells. Stem cells can also be used from a suitable donor, often a sibling.
Problems encountered in standard photon radiation therapy for lymphomas primarily occur in the necessity of reducing acute, and particularly late, toxicity. Due to a very good prognosis for patients with lymphomas (especially for patients with HL, with up to 80% long-term survival, and those with NHL with up to 60% long-term survival), and the age of disease manifestation, a large percentage of patients can survive long enough to develop late and very late toxicity, which may occur even several decades after the therapy. Given the presence of many high-risk structures with sensitivity to radiation damage in the area surrounding a lymphoma infiltrate or sites of original lymphoma infiltration, it is very important to minimise the dose to these high-risk organs.
Proton radiotherapy can be used to treat both Hodgkin and Non-Hodgkin lymphomas. Malignant lymphomas are a common diagnosis treated at proton centres around the world. The reason is the complexity of target volumes, the high curability of the disease and efforts to reduce late adverse effects in view of the expected long-term survival of patients.
The main advantage of proton therapy over conventional photon radiotherapy is in the significantly better radiation distribution, due to which improved treatment results can be achieved while reducing the toxicity of the therapy. The improved dose distribution patterns provide the opportunity to apply higher doses without inducing more severe side effects.
Proton radiotherapy makes it possible to significantly reduce the dose to critical structures, particularly in patients with mediastinal involvement. This involves a dose reduction to:
- Lung tissue
- Heart muscle
- Heart valves
- Coronary arteries
- Spinal cord
- Mammary glands
It also reduces the risk of developing secondary tumours.
Due to these advantages, proton radiation therapy was included in the treatment protocols of the National Cancer Comprehensive Network as the radiotherapy of choice for all types of lymphomas.
If you would like more information about proton therapy for lymphoma please have a look here