What happens in Hodgkin’s lymphoma, exactly?

What is it?

Hodgkin’s lymphoma is a type of cancer that affects a type of white cells called lymphocytes. Typical symptoms include a painless enlargement of one or many lymph nodes, fever, sweating at night, and loosing weight.

Hodgkin’s lymphoma is most common in young adults and those over 55. It affects around 2.7 people in 100 000. While the prognosis of the disease varies a lot depending on things like the age of the patient and the stage of the disease, the chances of survival are generally quite good. In a recent study, the five-year survival rate for those patients with a good prognosis was 98%, while for those in a worse situation it was at least 85%.

What causes it?

About half of the Hodgkin’s lymphoma cases are caused by the Epstein-Barr virus. It belongs to the family of herpes viruses and is one of the most common viruses in humans. Viruses are essentially protein shells that carry DNA inside them. When they invade a cell, this DNA becomes a part of the cell’s DNA. The genes found in DNA are what make the cell do things, and through this, viruses are able to make the cell produce new viruses according to their instructions. When the Epstein-Barr virus infects a lymphocyte, it makes the cell produce certain proteins that give the cell the ability to divide endlessly. Cancer happens when cells start to divide uncontrollably – this is why the virus can cause the lymphoma to emerge.

Mutations happen in our cells all the time, and sometimes when they happen in genes that control cell growth and communication, cancer can arise. Our body has systems in place, but in AIDS the cells that are supposed to kill the potential cancer-causing cells are struggling. This is why having HIV or AIDS also increases the risk of developing Hodgkin’s lymphoma.

What happens during it?

Lymph nodes are an important part of our immune system. If we get sick they can get enlargened, because there are more white cells than usual trying to fight the invading microbes. When the white cells encounter  a microbe, they start producing molecules that make other white cells come to the site of infection, and promote their division and growth. In Hodgkin’s lymphoma the cancerous cells start producing these substances and cause other, healthy white cells to gather in the lymph nodes. These cells, in turn, produce substances that promote the growth of the cancerous cells. The cancerous cells only make up a small proportion of the total weight of the tumor – most of it is composed of normal cells.

The reason why Hodgkin’s lymphoma causes fever is not fully understood. It is thought that the tumor might produce some toxins that start an immune reaction in the body. The weight loss associated with cancer is thought to occur because some substances reduce the body’s ability to use the energy from food, while some other substances start to actively destroy the proteins in muscles. The increased energy demand of the tumor’s quickly dividing cells also plays a role, especially in aggressively growing cancers.

How can it be treated?

The main lines of treatment  for Hodgkin’s lymphoma are chemotherapy and radiotherapy. Cancer cells divide far more often than normal cells, and these therapies work because they kill dividing cells. The body has, however, always many normal cells undergoing division, which is why there always is some collateral damage to the body. Stem cell transplants are also fairly commonly used.

 

 

 

Sources: https://en.wikipedia.org/wiki/Hodgkin%27s_lymphoma, https://en.wikipedia.org/wiki/Epstein%E2%80%93Barr_virus, http://www.cancer.org/cancer/hodgkindisease/index, http://www.cancerresearchuk.org/about-cancer/type/hodgkins-lymphoma/about/symptoms-of-hodgkins-lymphoma, http://www.nhs.uk/conditions/Hodgkins-lymphoma/Pages/Definition.aspx, http://www.cancerresearchuk.org/about-cancer/coping-with-cancer/coping-physically/fever/cause/the-cancer-itself, https://en.wikipedia.org/wiki/Cachexia

 

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