If you or a loved one have been diagnosed with cancer, you’re probably wondering: is cancer contagious?
Cancer is NOT contagious (i.e. it is not a communicable disease). People who are healthy can’t “catch” cancer. This is because the cancer cells of another person are recognised as “foreign” in other bodies. Your immune system will destroy the cancer cells of a normal person, because your body recognises they aren’t supposed to be there.
Close contact with a cancer patient won’t give you cancer. Holding hands, kissing, touching, sex, and sharing food or drinks has never been shown to spread cancer from one person to another.
Cancer doesn’t spread the way that coughs and colds do because cancer is not a germ. Germs (bacteria and viruses), have evolved to spread quickly and survive in lots of different people for long periods of time. Germs are very contagious and spread easily from person to person – even through the air.
Unlike germs, cancer cells develop from mutations in a person’s DNA. Sometimes, the DNA changes occur because of genetic predisposition. Other times, exposure to specific conditions can cause a cell’s DNA to change and become cancerous. Smoking, sun (UV) exposure and some substances like asbestos are all known to cause cancer. In any case, when the cell’s DNA is modified, its growth and division capabilities change. The cells grow, divide, and spread too rapidly. This leads to the development of tumours.
Cancer isn’t contagious, but germs and viruses are
While cancer itself cannot be passed from person to person, there are several viruses and some bacteria which can make the development of cancer more likely and which can easily be transmitted between people.
Bacterias that can lead to cancer:
- H. pylori: Helicobacter pylori is a bacteria that lives in the lining of the stomach wall. In some cases, H. pylori can cause ulcers, but for many people, the bacteria does not cause any issues. Stomach cancers are linked to H. pylori, and some studies show that people infected with the bacteria have a greater risk of developing bowel cancer.
Parasites that can lead to cancer:
- Blood & Liver worms: Two small liver worm parasites and one blood worm parasite are thought to be linked to some bile duct cancers and bladder cancers. However, these parasites are very rare in developed countries, and infection rates are low in the UK and the US.
Viruses that can lead to cancer:
- HPV Viruses: human papilloma viruses can cause skin cells to grow very rapidly, with new virus traces inside each cell. In some cases, HPV can damage cells’ DNA and cause them to grow and divide quickly. This can lead to cancer.
HPV is spread through close skin-to-skin contact, usually during sexual activity. And HPV is linked to cancers in the vagina, vulva, cervix, penis, anus, throat, mouth, head and neck. That said, there are over 100 strains of HPV, 30 of which affect the genital area. Of these, only 2 strains are known to cause cervical cancer. Many people have the HPV virus and never develop symptoms or cancer.
HPV is preventable. Regular cervical screening for women can help to identify the virus in its early stages. An HPV vaccine is also available. Lastly, practising safe sex and using condoms can also help to reduce your risk. Some early evidence shows that men and women should both be vaccinated against HPV, as both partners risk becoming ill themselves or infecting each other.
- EBV Virus: The Epstein-Barr virus is very common. More than 9/10 people are infected worldwide, and the virus spreads through saliva. When it’s contracted later in life, EBV often leads to glandular fever or “mono” (mononucleosis).
In some cases, EBV has been linked to the development of cancer; specifically Non-Hodgkin Lymphoma, Burkitt’s lymphoma, and nasopharyngeal cancer (a head and neck cancer). Most people will not experience any symptoms or develop cancer.
- Hepatitis Viruses: Hepatitis B and Hepatitis C are spread through blood-to-blood contact or unprotected sex. In many cases, Hep B is fought off by the immune system without issue. In some cases, however, it can cause long-term problems with inflammation in the liver. Hep C is more likely to become persistent and to cause liver damage.
In both cases, persistent infections are connected to higher rates of liver cancer, although the connection between Hep B and C and cancer isn’t clearly understood. Both Hep B and C are preventable through vaccination, good hygiene practices, and safe sex with condoms.
- HIV: The human immunodeficiency virus (HIV) weakens the immune system. When the immune system is weak, the body is less able to identify and destroy cells that are infected with cancer-causing viruses. Kaposi Sarcoma and Non-Hodgkin Lymphoma are typically linked to HIV.
- HTLV-1: Human T-Lymphotropic virus type 1 can cause a kind of Non-Hodgkin Lymphoma. HTLV-1 is transmitted through blood and bodily fluids, but many adults who carry the virus will never develop the disease, and infection itself is rare.
Cancer and Pregnancy
Can a pregnant woman pass cancer to her fetus?
If a woman has cancer and becomes pregnant, it is very unlikely that the cancer will affect her baby (fetus). In some cases, cancer has spread from the mother to the placenta – which is the soft-tissue organ that feeds the baby in-utero. And there are a few documented cases where a mother has directly passed cancer to her baby in this way. Still, the risk of passing cancer from mother to child in-utero is extremely low.
Can a pregnant woman be around someone getting cancer treatment?
It is safe for pregnant women to visit – and be around – people receiving chemotherapy. Although chemotherapy drugs remain in the body for 2-7 days after treatment, they are only passed into bodily fluids like blood, urine, sweat, semen and breast milk. If your partner is receiving chemotherapy treatment, speak to your doctor before you have sex. They may recommend using a barrier method or refraining from sex for a brief period of time to allow the chemotherapy drugs to wear off.
If you are pregnant and living with cancer, and wondering about whether or not you should breastfeed, speak to your doctor as soon as possible.
If you are planning to visit someone who has undergone radiotherapy, chances are, there’s nothing to be worried about. Conventional radiotherapy is “external-beam” radiation, which means that the x-ray or photon beams are delivered to the body from an external accelerator machine. Patients receiving this kind of treatment are not “radioactive” and it is perfectly fine for them to be around other people.
However, patients receiving internal radiation therapy must remain separate from other people for a period of time after their treatment. This is because internal radiation therapy is performed by inserting radioactive material directly into the cancer or surrounding tissue. The radiation remains very active in the body for anywhere from a few hours to a few days.
Doctors recommend that people who are pregnant do not visit or stay in close contact with a patient who has received internal radiation therapy.
Even for those who are not pregnant, visits should be limited to 30 minutes or less. Visitors should remain at least 2 meters away from the patient’s bed.
Because the radiation can remain active (in lower doses) in the patient’s body for several weeks and months after treatment has ended, doctors also recommend that pregnant women stay away from these patients for a period of 2 months.
Is it safe for babies to be around chemotherapy or radiotherapy patients?
It is safe to take your baby to visit a family or friend who is having chemotherapy. As it is highly unlikely that your baby will come into contact with any bodily fluids that may contain traces of the chemotherapy, the risks are very low. Just make sure the person having chemotherapy doesn't kiss the baby and pass on their toxic fluids from their lips.
If the person you are planning to visit has had conventional “external” radiation therapy, then it is safe for babies and children to visit and spend time with them. But if the person has received “internal” radiation therapy, then doctors recommend that no one under the age of 18 visits or spends time with them for a defined period after treatment ends. This “waiting” period can last up to 2 months.
For more specific guidelines, speak to your doctor and ask the person with cancer to seek advice from their healthcare team, too. Together, you’ll be able to make a plan that suits everyone.
Before you make plans, think about the patient and their needs in addition to yours. Cancer patients are often very susceptible to illness and need to limit their exposure to germs. Bringing babies and young children (and their coughs and colds) to visit someone with cancer might have unintended consequences. As always, ask the person themselves about what they would prefer – and then respect those preferences!
Cancer and Organ Transplants
Can cancer be transmitted through organ transplants?
In some rare cases, people who have received an organ transplant from a person with cancer have later developed cancer themselves. This happens very infrequently and people who are selected as organ donors are screened for a variety of things; including cancer.
But there are other factors that make cancer more likely in organ transplant recipients. People who receive transplants have to be placed on medication that weakens their immune systems so that their bodies accept the new organs (instead of attacking them as “foreign” objects). Compromising the immune system like this makes transplant recipients much more likely to become sick. The immune system is less able to recognise and destroy cancer cells or infections that can cause cancer.
Cancer is contagious in some animals
Although cancer isn’t contagious in humans, some animals can catch cancer. You may have heard about Tasmanian devils in the news. These tiny predators can transmit a type of cancer that leaves them with large facial tumours. Scientists have named the cancer “devil facial tumour disease” or DFTD. Tasmanian devils pass it on to each other through skin-to-skin contact.
Some dogs can also pass a type of tumour back and forth to each other through genital skin-to-skin contact.
Lastly, and most bizarrely, soft-shell clams can be infected with a contagious type of leukaemia. Scientists are studying how the cancer passes between the clams and whether or not similar things could happen to other ocean species. So far, though, the clams are all that’s been documented.
The bottom line? Cancer isn’t contagious.
So you can – and should – feel free to interact normally with the cancer patients in your life. Ask your doctor about any questions related to sex, breastfeeding, or exposure to the person’s bodily fluids after their treatment.
If you’re looking for tips about what to say and what not to say to cancer patients, we have a few suggestions. And if you need some ideas for cancer gifts, or ways to help someone with cancer, we’ve got you covered, too.