Cancer-causing viruses: How hepatitis C can lead to lymphoma

Being in the midst of the coronavirus pandemic means we have been inundated with an avalanche of information about the deadly respiratory symptoms caused by Covid-19.

We know by now that Covid-19 is caused by the coronavirus, but did you know that viruses can also be the cause of certain types of cancers?

In the first of this four-part series, we will be looking at the role in which viruses play in the information of certain blood cancers such as lymphoma.

Viruses and lymphoma

Dr Colin Phipps Diong, Senior Consultant in Haematology at Parkway Cancer Centre shared with us how many may be unaware that viruses such as hepatitis C and the Human Immunodeficiency Virus (HIV) are associated with lymphoma, or cancer of the lymph nodes.

Said Dr Phipps: “Lymphoma is cancer of the lymph nodes or more accurately, the lymphatic tissues. It usually affects the lymph nodes which are normally areas where lymphocytes (immune system white blood cells that fight infection) mature and grow. It can also affect other areas of the body like the bone marrow, stomach, intestine, brain, and so on.”

According to the Singapore Cancer Registry, lymphoma is the fourth most common cancer in men and the sixth most common cancer in women in Singapore.

Dr Phipps added that lymphoma can develop when these lymphocytes grow out of control.

So how do viruses play a part then?

Dr Phipps shared: “Some viruses can incorporate themselves into normal cells, usually into the main part controlling cell programming, which is the area that controls how the cells behave, develop, grow, and die.”

One example, says Dr Phipps, is a virus in the herpes family known as Epstein-Barr virus (EBV), which can make a normal cell grow into a cancer or blood cancer such as lymphoma.

This would usually occur in patients who have a severely weakened immune system that cannot prevent the EBV from penetrating the lymphocytes. Another virus that would cause a patient to have a weakened immune system is HIV.

Said Dr Phipps: “HIV is associated with a common form of lymphoma called large B-cell lymphoma but other types of lymphomas like Hodgkin’s lymphoma can also be related.”

In the case of hepatitis C, which is spread through exposure to infected blood, the cause is not quite so clear, but it is postulated that the long-term infection causes the immune system to go into overdrive in trying to kill the virus.

“As more and more lymphocytes are recruited to fight the chronic hepatitis C infection, there is a greater chance for mutations in key genes to occur, which might eventually lead to lymphoma,” explained Dr Phipps.

“Hepatitis C is associated with a specific subtype of B-cell lymphoma that usually affects the spleen with or without affecting other lymph node areas,” he added.

Another virus, called the Human T-cell leukaemia virus (HTLV-1), is also found to be responsible for a rare form of T-cell lymphoma called adult T-cell leukaemia/lymphoma.

However, one should note that virus-linked lymphoma cases are still a minority in Singapore, comprising only “about 5 per cent” of cases that Dr Phipps sees.

While there are more than 60 subtypes of non-Hodgkin’s lymphoma, the most common type of aggressive lymphoma in Singapore and worldwide would be large B-cell lymphoma.

Symptoms and treatment

Common symptoms of lymphoma in general include prolonged fever, unexplained weight loss, poor appetite and drenching night sweats.

One positive piece of news for those afflicted with lymphoma though, is that the disease is highly treatable, even in elderly patients. Although symptoms may present themselves only in the advanced stages, large B-cell lymphoma, for example, has a high cure rate of “around 55 per cent”, said Dr Phipps.

While being diagnosed with viral infections such as HIV and hepatitis C together with lymphoma presents certain challenges, it can still be treated.

For HIV patients, the amount of chemotherapy used to eradicate the cancer will have to be modified, and patients will have to continue taking the anti-HIV medication to kill the virus.

In the case of hepatitis C-related lymphoma, some patients can be treated with anti-viral medication alone and this will cause the lymphoma to shrink without the need for chemotherapy.

Dr Phipps, who has more than 10 years of experience in treating patients with blood cancers, occasionally has to assure them that lymphomas “are in no way contagious”.

And while lifestyle habits such as smoking or drinking alcohol do not increase the risk of getting lymphoma, other factors come into play.

High chemical exposure, particularly benzene, for those working in the rubber, oil and gas industries for example, is one factor which may increase the risk of contracting lymphoma.

Besides that, long-term bacterial infections such as Helicobacter pylori infection of the stomach, Chlamydophila psittaci infection of the eye and Campylobacter jejuni infection of the intestine can also increase the risk of getting lymphoma.

Helping patients achieve cure

Treatment for lymphoma usually involves four to six months of chemotherapy, depending on the severity.

Due to the length of time required for treatment, Dr Phipps gets to establish a warm relationship with his patients.

“The best thing is to help patients achieve cure, and the worst is when you lose patients,” shared Dr Phipps, whose day starts at 7 am and involves visiting patients in wards, performing procedures and seeing patients at his clinic.

“When you treat cancers such as acute leukaemia or lymphoma, the treatment is quite long. Especially (in the case of leukaemia) if patients have to go for transplants they remain your patients for very long and will follow up with you very closely for the first year. It’s nice to see them when they are much better and can actually go back to their normal lives and their jobs,” said Dr Phipps.

This article was brought to you in partnership with Parkway Cancer Centre.