Is Cancer Contagious?

Cancer is not contagious, and does not spread from person to person. It cannot be caught by touching, kissing, or breathing the same air as someone with cancer. If your body were to come in contact with a cancer cell, your healthy immune system would destroy it before it becomes a problem. 

There are rare instances, though, when cancer genes can be passed from one individual to another. These genes could be passed from a parent to a child or from an organ donor to a recipient. It is also possible to catch a virus that puts you at higher risk of developing cancer such as the human papillomavirus (HPV). 

Female doctor in discussion with senior male patient and adult daughter in exam room - stock photo

Thomas Barwick / Getty Images

How Cancer Develops

Cancer occurs when cells in the body start to divide and multiply at an out-of-control rate. Normally the cells in our bodies grow and divide as we need them. When older cells die, new ones are created. When a cell’s DNA is damaged, the process gets thrown off. Old cells do not die off like they should, and new cells are formed when they’re not needed. This fast growth rate can cause cancerous cells to grow and form tumors in the body.

Damage to a cell’s DNA is usually caused by mutations from environmental exposures. Coming in contact with UV rays from the sun or smoking damages the DNA in our genes and causes changes to the ways cells divide, potentially leading to cancer. These changes in our genes can also be inherited from our parents. 

DNA damage, illustration - stock illustration


From a Parent

Most cancers are not hereditary. Rather, mutations in the cell develop over a lifetime of environmental or hormonal exposures. In hereditary cancers, an individual inherits a gene with a mutation from one or both parents. Inheriting this gene puts the person at a higher risk for cancer, but does not mean that a cancer diagnosis is inevitable. Cancers of the ovaries, breast, colon, and prostate may be passed down in a mutated gene. 

Tumor Suppressor Genes

Tumor suppressor genes are responsible for controlling the growth of cells. They tell cells when to divide and when to die off. They can also help repair damaged DNA. When these genes don’t work as they should, cells can grow uncontrollably, resulting in cancer. 

Most mutations in tumor suppressor genes are acquired, meaning they develop over a lifetime. There are times, though, when these genes are inherited from parents. For example, parents are able to pass on mutations in the TP53 gene, which is found in about half of all cancer cases. 

DNA Repair Genes

DNA repair genes are responsible for repairing any damage to the cell’s DNA, as well as protecting the DNA from future damage. Once DNA is damaged, it can lead to cells growing at an uncontrolled rate and cancer. You may have heard of the genes BRCA1 and BRCA2 (breast cancer 1 and 2). These are examples of DNA repair genes that can be passed from parents to children. Women who inherit one of these genes from their parents are at higher risk for developing breast and ovarian cancer. 

During Pregnancy

Passing on cancer genes during pregnancy is incredibly rare. Experiencing cancer while pregnant is also rare. Usually, if a mother is being treated for cancer during her pregnancy, the baby will not require special preventive treatment. 

If a mother with cancer is breastfeeding, cancer cells will not enter the baby while the mother’s cancer treatments could. Chemotherapy can be ingested through breastmilk; talk with your oncologist and pediatrician about the best plan for feeding your baby if you are being treated for cancer while breastfeeding.

Some cancers are able to spread through the placenta, the organ that connects the mother and baby, but most cannot reach the fetus. There have been rare cases of melanoma, small cell lung cancer, non-Hodgkin lymphoma, and leukemia that were passed from mother to child. 

From an Organ Transplant

There have been rare cases of an organ donor recipient developing cancer after receiving an organ from someone with a history of cancer. This is rare, partly because of the strict requirements and screening processes for organ donors.

It’s important to remember that individuals receiving a new organ are required to take medications that suppress their immune systems. This helps to ensure that their bodies will not reject and attack the new organ as a foreign body. Because their immune systems are already weakened, they are at higher risk for developing cancer. Studies show that the longer a patient’s immune system is suppressed, the more at risk they are for being diagnosed with cancer. A weakened immune system cannot recognize and destroy precancerous cells as effectively as a healthy one.

According to the National Institutes of Health, organ transplant recipients are at higher risk for 32 types of cancers. Studies have found that the most common cancers experienced after an organ transplant are non-Hodgkin lymphoma, lung cancer, liver cancer, and kidney cancer. The risk varies by what type of organ is received.

Patients who have undergone a lung transplant are at the highest risk of developing cancer later on. Researchers believe this increased cancer risk is due to the remaining lung tissue in the recipient, rather than the new lung. Patients who receive liver transplants are at higher risk for liver cancer. 

How Common Is It?

According to a study from the National Institutes of Health, patients who have received organ transplants are at two-fold risk of developing certain types of cancers. Of the patients they studied, 14% developed non-Hodgkin lymphoma, 13% developed lung cancer, 9% developed liver cancer, and 7% developed kidney cancer. The risks for these cancers depend on which organ was transplanted.

From an Infection

There are certain infections like an HPV infection that have been linked to a higher risk of cancer. It’s important to remember that being diagnosed with the virus itself does not mean that you will develop cancer. The virus alone cannot create cancer in the body, but when it is combined with a weakened immune system or environmental risk factor like smoking, the risk for cancer goes up. It is possible to catch viruses through touching, kissing, having sex, sharing food or breathing the same air. Each virus has its own methods of spreading.

In addition to viruses, there are bacterial infections and parasites that can also raise your cancer risk. The bacterium Helicobacter pylori irritates the lining of the stomach, and long-term infection can raise your risk for stomach cancer. Parasitic worms that enter the gastrointestinal tract can raise your risk for cancers of the bladder and bile ducts. These parasites are very rare in the United States. Most cancers are not caused by infections.

 Microbe Types of Cancer
 Human papillomavirus (HPV) Cancers of the cervix, vagina, vulva, penis, anus, and some cancers of the mouth, throat, head, and neck
 Epstein-Barr virus (EBV) Nasopharyngeal cancer, lymphoma of the stomach, Hodgkin lymphoma, and Burkitt lymphoma
Hepatitis B virus (HBV) and hepatitis C virus (HCV) Liver cancer
 Human herpes virus type 8 (HHV-8) Kaposi sarcoma (only with a weakened immune system)
 Human T-lymphotropic virus-1 (HTLV-1) Adult T-cell leukemia/lymphoma (ATL)
 Merkel cell polyomavirus Merkel cell carcinoma
 Helicobacter pylori (H. pylori) Stomach cancer
 Chlamydia trachomatis Cervical cancer

A Word From Verywell

If you have a loved one with cancer, you are probably feeling overwhelmed with worry and responsibility. It’s helpful to remember that cancer is not contagious and you cannot catch it from another person. To protect yourself from developing cancer, take efforts to avoid environmental exposures such as too much time in the sun or cigarette smoke. In addition, take precautions to avoid the viruses that can lead to cancer. Your doctor can help you learn more about your cancer risk and how to reduce them. 

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Article Sources
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  2. National Cancer Institute. Common Cancer Myths and Misconceptions. Updated August 22, 2018. 

  3. National Cancer Institute. What Is Cancer? Updated February 9, 2015.

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  5. Memorial Sloan Kettering Cancer Center. Hereditary Cancer & Genetics. Updated 2020.

  6. American Cancer Society. Oncogenes and Tumor Suppressor Cells. Updated June 25, 2014. 

  7. Genetic Testing. Updated June 26, 2020.

  8. Greaves M, Hughes W. Cancer cell transmission via the placenta. Evol Med Public Health. 2018 Apr 14;2018(1):106-115. doi: 10.1093/emph/eoy011

  9. Canadian Cancer Society. Cancer During Pregnancy. Updated 2020.

  10. National Institutes of Health. Organ Transplants and Cancer Risk. Updated November 21, 2011.

  11. Chapman JR, Webster AC, Wong G. Cancer in the transplant recipient. Cold Spring Harb Perspect Med. 2013 Jul 1;3(7):a015677. doi: 10.1101/cshperspect.a015677.  (ADD READING)

  12. Engels EA, Pfeiffer RM, Fraumeni JF Jr, Kasiske BL, Israni AK, Snyder JJ, Wolfe RA, Goodrich NP, Bayakly AR, Clarke CA, Copeland G, Finch JL, Fleissner ML, Goodman MT, Kahn A, Koch L, Lynch CF, Madeleine MM, Pawlish K, Rao C, Williams MA, Castenson D, Curry M, Parsons R, Fant G, Lin M. Spectrum of cancer risk among US solid organ transplant recipients. JAMA. 2011 Nov 2;306(17):1891-901. doi: 10.1001/jama.2011.1592

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