Is Cancer Contagious?
Cancer can be frightening, and misunderstandings about how it spreads can add to that fear. Some infections that spread between people can raise cancer risk. Shared genes, lifestyles, or environments risk factors can also affect people in the same family or community. But cancer itself cannot be spread through close contact. Knowing the facts can help you feel more confident offering support and staying connected.
Cancer is NOT contagious
Some people believe cancer can spread from person to person. But you can’t “catch” cancer from someone else. Close contact like touching, holding hands, sharing meals, kissing, having sex, or breathing the same air can’t spread cancer. Cancer cells in a person with cancer are not able to get inside and live in the body of another person.
Understanding why cancer is not contagious
Although cancer is not contagious, there are some situations that can make people think that cancer has spread from one person to another. When people don’t know how cancer develops, they may believe it can spread between people. This misunderstanding can cause fear and spread misinformation. Understanding the causes of cancer can help people feel less afraid and be better informed.
Infections can increase cancer risk
Although cancer itself is not contagious, some viruses, bacteria, and parasites have been linked to a higher risk of certain types of cancer. This may lead some people to wrongly think they can catch cancer from another person who has a certain infection or a certain type of cancer. While it’s true that many of the infections that can affect cancer risk can be passed from person to person, cancer itself can’t be spread. Learn more in Infections that Can Lead to Cancer.
Cancer that runs in families
Cancer can’t be spread from one family member to another. If it were contagious, there would be high rates of the same cancers among family members, friends of people with cancer, and health professionals who care for them. This is not the case.
This misunderstanding might come from hearing about families who have a family cancer syndrome. These are conditions caused by gene changes that can be inherited (passed down) from parents to children. Having a family cancer syndrome means a person has a higher risk of developing certain cancers, but it does not mean a person will “catch” it from a family member. If you hear about certain cancers running in families, it’s important to remember that family members:
- Share the same genes
- Often have similar unhealthy lifestyles (such as diet or smoking)
- Might have been exposed to the same cancer-causing agent
Cancer clusters in communities
A cancer cluster is a pattern in which a higher than usual number of cancer cases are diagnosed in a specific geographic area. Some people may think that a group of people with cancer who live near each other or work together means cancer is contagious. But when a cancer cluster is suspected or identified, there’s usually a concern about a possible cancer-causing agent in the environment.
It’s also possible that people living or working in the same location have similar lifestyle behaviors, such as smoking or having limited access to healthy foods. In rare cases where there is more cancer in a certain group of people, it can be hard to know what factors are responsible for the cancer cluster.
Cancer passed through organ transplant
An organ transplant involves moving a living organ from one person to another. That organ is made up of millions of living cells. In rare cases, cancer cells can be passed from a donor to a recipient during an organ transplant. This can happen if the donor’s organ had cancer cells that were not known at the time of donation. Doctors call this donor-transmitted cancer (DTC). Organ donors are carefully screened for signs of cancer to reduce this risk.
Another concern for organ transplant recipients is that their immune system might not work as it should. A healthy immune system continuously looks for anything that doesn’t belong in the body and attacks it. After a transplant, this natural response can cause the immune system to attack the new organ. To prevent this, people who get organ transplants must take medicines to weaken their immune systems so their bodies don't attack and destroy the transplanted organ. Because these medicines weaken the immune system, they can also reduce the body’s ability to find and attack damaged cells and viruses that can lead to cancer.
Cancer and blood donation or transfusion
Sometimes, people who get a blood transfusion because of anemia or another health problem are concerned about catching diseases from a donor’s blood or blood products. Similarly, cancer survivors who want to donate blood might worry that they could give cancer to the person who receives their blood. Research has not found that cancer can spread through a blood transfusion.
Keep in mind that people with certain types of cancer may not be eligible to donate blood. For example, those with Kaposi sarcoma or a hematologic (blood) cancer, such as leukemia, lymphoma, or multiple myeloma, will not be able to donate blood or blood products. Certain types of cancer treatment may also make some cancer survivors unable to donate blood. Learn more about blood and organ donation in Can I Donate My Blood or Organs if I’ve Had Cancer?
Cancer passed during pregnancy or labor
Very rarely, cancer cells can move from a pregnant person to the fetus (unborn baby). This is extremely uncommon. Most babies are not affected, even when cancer is diagnosed during pregnancy.
Research has suggested cancer cells might reach the fetus if the pregnant person has advanced or metastatic cancer that has spread to other areas of the body. But again, these situations are very rare. Before birth, the placenta (the sac where the fetus grows in the womb) protects the fetus, including filtering out abnormal or harmful cells.
It’s also very rare for cancer cells to be transferred to the baby during labor and birth.
People with cancer need to be around other people
The belief that cancer is contagious can lead to fear. It can make a person avoid someone with cancer. This can leave people with cancer feeling isolated or treated differently. This is called stigma. Being stigmatized or blamed can worsen stress, anxiety, and depression.
Reducing stigma matters, and clear information helps replace fear with facts. Remember, you can’t catch cancer from someone who has it. Don’t be afraid to reach out. People with cancer need connection, visits, and support from people in their lives.
- Written by
- References
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
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Last Revised: February 13, 2026
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
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