Cancer Mythbusters: Is Cancer Contagious?

Read the transcript:

MEGAN: Hi, I'm Megan Riesz, and this is Cancer Mythbusters, a podcast from Dana-Farber Cancer Institute about the many myths and misconceptions in the world of cancer. Every episode, we'll take a look at a myth and debunk it with the help of our world-leading clinicians and researchers.

It's probably a vast underestimation to say that a cancer diagnosis can inspire an endless stream of questions:

• "Am I going to be OK?"
• "How can I get the best treatment?"
• And, of course, "How did this happen to me?"

Researchers are still trying to figure out why certain cancers develop in certain people. Some cancers can be explained by factors like smoking and excessive use of alcohol, or by genes passed down the family line.

But can cancer be spread from person to person? And if not, what are some ways we can reduce the negative stigma that cancer patients can experience?

We'll get to the bottom of all of this with Dr. Ann LaCasce, lymphoma specialist and Director of the Dana-Farber/Partners Cancer Care Fellowship in Hematology and Oncology.

MEGAN: Thank you for joining me, Dr. LaCasce.

DR. LACASCE: Thanks so much for having me.

MEGAN: To start this off, generally speaking, can one person spread their cancer to another person by close contact or by any other means? And if not, what is it about cancer cells that prevents this from happening?

DR. LACASCE: No, really, cancer is not a contagious disease. We know that cancer is caused when an individual cell gets a mistake in the machinery of that cell, in the DNA or other parts of the cell, that causes that cell to grow and divide, basically, out of control. For many cancers, we don't really know what the causative agents are. It's probably multiple things over many years, but it is clearly not a contagious disease or transmissible between people.

Cancers are incredibly common. We know that, in their lifetime, 1 in 2 men and 1 in 3 women will have a cancer, and there are many, many different types of cancer, and I think educating patients as much as we can about cancer demystifies it and makes it less scary. Really, we need to emphasize to our patients and their families that these patients need support and have folks rally around them, and there is absolutely nothing that will cause a cancer to be passed directly to another person, except in extremely rare circumstances, which we'll talk about.

MEGAN: Going off of that, what are some of the rare circumstances in which cancer can be passed from one person to another?

DR. LACASCE: There have been some extremely rare case reports of a pregnant woman with a metastatic cancer passing that on to the baby. Typically, the placenta is extremely good at detoxifying and destroying, preventing cells from traversing to the baby. There have been some very rare circumstances where a surgeon develops a melanoma with a needle stick or an injury during surgery where there are tumor cells.

But in general, the body's own immune system has a means of detecting and destroying these very small numbers of tumor cells when people are exposed, so we really don't think about that really ever. I've never seen that happen. There are some cancers that are driven by viruses. Patients who have HIV are more susceptible to a number of different types of cancer, but it's not that the cancers in any way are transmissible between patients and their contacts. It just affects the immune system in such a way that predisposes patients to developing a cancer in rare circumstances. But even now, in the era of very good treatments for HIV, the cancer rates are generally down significantly.

There are some other viruses, like Hepatitis C, that are associated with particular cancers, but it's not that the cancer is transmissible; it's that the infectious disease is and can put someone at a slightly higher risk, meaning patients who have these underlying infections need to be followed closely by their physicians to make sure that they don't develop a cancer, but it's not that they pass them on to somebody else.

MEGAN: If cancer is not technically contagious, how do you explain the higher incidence rate of cancers in certain families?

DR. LACASCE: We know that there are some genes that you're born with that may predispose you to developing certain types of cancer down the line. Probably the one that people know the most about is BRCA1 and BRCA2. We know that patients who inherit this have a higher risk of subsequently developing cancers. Not everybody who has that will develop cancer, but we know we need to follow these patients carefully.

We have a really great genetics clinic here, and we are screening more and more patients for these particular predispositions so that we can follow them appropriately. Not to scare them or have them be worried all the time but to really educate patients about the proper screening. Now that we're learning so much about genetics, there are more and more of these genes that we're beginning to understand who has these genes, what particular cancers they may be susceptible to, and what are the other factors that play a role in the development of cancers in these folks.

MEGAN: Are there cancer-causing bacteria and viruses that are contagious? If so, what are some tips for avoiding these bacteria and viruses?

DR. LACASCE: We know that the viruses HIV and Hepatitis C are associated with certain types of cancers, so practicing safe sex, and when people are working in the medical community, using precautions to make sure that they're not exposed to body fluids. The virus that causes mono, Epstein-Barr virus, is associated with some certain types of cancer, particularly lymphomas, but this is a virus that almost everybody has been exposed to, and I think there's really not an increased risk, in general, with that particular virus. I think it's just, for those viruses, education and getting good, routine medical care to screen for those particular viruses if you're at risk.

MEGAN: As we mentioned before, the myth that cancer is contagious can lead to some cancer patients experiencing negative stigma, so there's no reason that someone should avoid someone who has cancer, is there?

DR. LACASCE: No, I think the opposite is true. We need to be supporting patients who have cancer because everyone is going to know or be personally affected by cancer at some point in their lifetime, and it's really important that we demystify it and really educate people as to how we deal with these and what causes these cancers. Even though we don't have a lot of answers, we do know that they are not contagious.

MEGAN: Thanks so much for joining us, Dr. LaCasce.

DR. LACASCE: Thank you.

MEGAN: So, myth busted — cancer is not a contagious disease. There is nothing that will cause a cancer to be passed from one person to another, except for extremely rare circumstances. Some genes can lead certain families to develop certain kinds of cancers, but one does not inherit cancer; one inherits genes. Certain viruses can lead to certain cancers, and routine medical care and practicing safe sex is important for that reason. And it's important to surround cancer patients with all the support and love that we can give them.

See all Cancer Mythbusters episodes