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Does Chemotherapy Increase the Risk of Common Infections?
Brian Wojciechowski, M.D.
February 10, 2016

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In this podcast, Brian Wojciechowski, M.D.,’s medical adviser, explains a study published in January 2016 suggesting that chemotherapy for breast cancer may increase the risk of common infections.

Listen to the podcast to hear Dr. Wojciechowski talk about:

  • how the immune system works
  • how chemotherapy affects the immune system
  • when women who will be undergoing chemotherapy should get vaccines
  • steps you can take to support your immune system

Running time: 11:03

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Show Full Transcript

Jamie DePolo: Hello, everyone. Welcome to this edition of the podcast. I’m Jamie DePolo, the senior editor at, and today I’m joined by Dr. Brian Wojciechowski , who is the medical adviser. He’s a medical oncologist who practices at Riddle, Taylor, and Crozer Hospitals in Pennsylvania, and today we’re going to talk about a study that was published in January in the journal Breast Cancer Research looking at how chemotherapy for breast cancer could possibly affect a woman’s immune system long term.

So, Dr. Brian, welcome, and let’s jump right in. Can you tell us a little bit about how the immune system works?

Dr. Brian Wojciechowski: Yeah. Thanks for having me, Jamie. There are many components to our immune system, and it’s extraordinarily complex. The immune system consists of not only cells, mostly white blood cells that are able to recognize foreign invaders like bacteria, viruses, and eliminate them, but the immune system also consists of your skin, which blocks invaders, and even the mucus in your respiratory tract is part of your immune system because it carries those defense cells, and it prevents bacteria from entering your airways. Even your bacterial flora, the normal bacteria that live in your gut, have functions in your immune system.

So it’s a very complex system within your body that has many components. The main job of the immune system, however, as it relates to chemotherapy, is that there are white blood cells, also called lymphocytes, in your body that have the ability to recognize foreign invaders and tag them for attack and destruction by other white blood cells in the body.

Jamie DePolo: Okay. So there are many different kinds of white blood cells. So what does chemotherapy do to the immune system?

Dr. Brian Wojciechowski: Well, chemotherapy can deplete those white cells because chemotherapy not only attacks cancer cells, but really any cells in the body that are rapidly dividing. That’s why you get diarrhea, nausea, vomiting, and...

Jamie DePolo: Mouth sores, right?

Dr. Brian Wojciechowski: Yeah. […] And your blood counts drop during chemotherapy because those white blood cells are dividing and growing rapidly all the time. So chemotherapy can destroy some of those as well.

Jamie DePolo: Okay. Now, in the study, it found that women had lower levels of several types of lymphocytes, or white blood cells -- and now, as you said, these lymphocytes are white blood cells. Can you talk a little bit... I know the article went into detail about the very specific kinds. I think they mentioned T helper cells and a couple different other ones. Do all of those have different roles in the immune system, or do they all basically do the same thing and sort of kill the invaders?

Dr. Brian Wojciechowski: Well, the ultimate goal of all these cells is to kill the invaders, but they all have different functions. So, for example, the helper T cells are the cells that are diminished when someone has HIV or AIDS, and those cells basically help other immune cells by secreting substances that recruit other cells to come and kill the bacteria or viruses. B cells make antibodies, which are tiny little proteins that float around in the bloodstream, and they’re the ones that can recognize invaders and mark them for destruction by other members of the immune system.

Jamie DePolo: Okay. Okay. That’s helpful. So now the study found that -- and the study only lasted for 9 months. So when the study ended 9 months after the chemotherapy ended, the B cells and the helper T cells, those levels were still low. So I guess I’m wondering what does that mean overall for -- say it’s me and it’s my immune system. Am I going to get sick more easily? Am I going to get sicker than I normally would? Am I going to get sicknesses that I normally wouldn't get?

Dr. Brian Wojciechowski: That’s a very good question, and I don’t think the study fully answers that. I think it’s important to look at not just what this study showed, but also what it did not show. The study looked at levels of the immune cells themselves. It didn't look to see if the women actually had higher rates of infection. And I will say that when I see patients -- and when they go through chemotherapy, I’m seeing them, you know, 6 months later, a year later -- I haven’t noticed that they’re getting more infections. That’s not very scientific. It’s just my own personal observation.

So this study didn't really look at rates of infection in women after chemo, it just looked at levels of these immune cells. And it may be that the low levels of the immune cells don’t make a difference in the risk of infection. It may be that they do. We just don’t know that from the study.

Jamie DePolo: Okay. Okay. That’s a very good point, and that brings me to some of the questions that we’ve seen on our Discussion Boards at A lot of women want to know, should they get a flu shot whether they’re going to start chemotherapy, they’re getting chemotherapy, they just finished chemotherapy? And I know there are some recommendations about live vaccines versus attenuated vaccines and all those kinds of things. So if you could talk a little bit about that.

Dr. Brian Wojciechowski: Yeah. The common wisdom is that any vaccine that contains live virus should not be given while a woman is getting chemotherapy or up to even 3 months after she’s finished. Some examples of vaccines with live virus in them would include the varicella vaccine, the measles, mumps, rubella.

Jamie DePolo: I’m sorry. What’s varicella? Is that the measles, mumps, rubella, or is that something different?

Dr. Brian Wojciechowski: No. Varicella is the Zostavax, for the shingles. [Editor’s Note: The varicella zoster virus causes both chickenpox and shingles. Chickenpox is also known as varicella. Shingles is also known as herpes zoster. The varicella vaccines (brand names: Varivax, ProQuad) and the herpes zoster vaccine (brand name: Zostavax) all contain live virus.]

Jamie DePolo: Oh, got it. Okay. Okay.

Dr. Brian Wojciechowski: Yeah, and measles, mumps, rubella is MMR, and that’s different. Now, I don't want to get too far into recommending specific vaccines for individual patients. I think patients should see their primary doctor and discuss these things. But I generally tell my patients that if there’s any vaccines that you need just because you’re due for them at whatever age you’re currently at, to get those vaccines before you start chemotherapy, because that’s when they’ll be most effective in stimulating the immune response necessary to generate immunity. Because if I give you a flu vaccine while you’re on chemotherapy and your white blood cells are relatively low, the vaccine might not take. So it might not be able to generate that immune response. So, we try to get all necessary vaccines in before the start of chemotherapy.

Jamie DePolo: Okay. That makes sense, and just one last question about this. Does the whooping cough vaccine that’s now being added to tetanus for adults, do you know if that’s a live virus vaccine?

Dr. Brian Wojciechowski: No, that’s not live.

Jamie DePolo: Okay. Okay. Good to know, because I don’t know how many people are aware that that’s happening, because there have been the outbreaks of whooping cough among adults. So they’re starting to put that back in to try and stop that.

Dr. Brian Wojciechowski: Yes, indeed.

Jamie DePolo: I’ve seen some ads on television and in magazines talking about supplements to boost the immune system. Is that even possible? Can you actually eat something that’s going to improve your white blood cell count or make your immune system stronger?

Dr. Brian Wojciechowski: Yeah. I think there’s a lot of companies that will advertise taking certain supplements that will help boost your immune system. Unfortunately, what is lacking is a lot of good scientific evidence that would support those claims. Oftentimes, my patients ask me about different supplements that they could take to boost the immune system, and that’s what I tell them.

In many situations, taking it won’t do any harm, and I usually don’t have a problem if they want to do it, as long as they keep me in the loop and let me know what they’re taking. But I also try to tell them not to break the bank about it because those claims are not really backed up by strong scientific data.

The other thing I want to say is that there are ways you can care for your immune system and support it.

Number one, when a woman is on -- or a man, for that matter -- is on chemotherapy, we often give white blood cell booster shots that help increase white cells, one particular line of white cells called neutrophils, which are very important in fighting infection, and we know that those are effective. So that’s one way. As I mentioned before, the mucus in your airways and the tiny little hair-like projections called cilia in your airways are part of your immune system, and those can be affected by smoking. So, you know, we tell our patients not to smoke. That’s another way you can boost your immune system.

Having diabetes affects immune functions. So that means taking care of your health, and eating right, and getting yourself to a healthy weight, and get conditions like diabetes under control. So I think if a chemotherapy patient is not smoking, is eating right, and is keeping herself at a healthy weight, that she’s way ahead of the pack in terms of supporting the immune system.

Jamie DePolo: And I have to ask, what about sleep? I’ve read that sleep is very important for the immune system.

Dr. Brian Wojciechowski: Yeah. Sleep is important for a lot of things, including the immune system. I know that during times in my life when I’ve not been sleeping well, say, when I was in medical training, I used to get more frequent infections. So I’m definitely a proponent of good sleep hygiene.

Jamie DePolo: Okay, great. Dr. Brian, thank you. This has been really helpful, and we hope that anybody out there who’s about to start chemotherapy or undergoing chemotherapy learned a lot from this. Thank you so much.

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