Lymphocytes are specialized and very important cells of the human immune system and in a lymphoma patient these cells get affected and become cancerous. As a result immune response to bacterial and viral attack become weak. According to me lymphoma is the most dangerous type of cancer, as the sufferers realize it in the later stages.
There are two main age groups, which are likely to be affected from lymphoma, one is 25 to 35 and second is above 60s. Immune system of people above 60s become weak naturally and prone to infection, and as a consequence body is no longer able to eradicate the mutated cells and these cells multiply and change in to cancer. On the other hand researches had shown that 25 to 35 years old people are also more susceptible to this disorder.
There is a little bias in the disease regarding gender; men are three times more susceptible to the disease than women. Some scientists think that Female hormones may protect from disease, as the women become aged and hormone level decreases, the chances of developing lymphoma starts equal to their male counterparts. On the other hand male hormone make men more susceptible and with decrease in hormone level male become less prone to the disease.
Geographically Western countries like UK, America, Australia and Germany etc have higher incidences of lymphoma than Asia and Africa. Their rich lifestyle with alcohol and fatty foods and polluted environment with carcinogenic substances dispose westerners to lymphoma.
But, this not answerable why some people get affected and others not, while both are living in similar environment.