Rich Dietman: Welcome to Mayo Clinic podcast. Our topic today is adjuvant chemotherapy for cancer — what it is and when it's used. I'm your host, Rich Dietman.

In today's podcast we're talking about adjuvant chemotherapy and its role in treating certain cancers. My guest is Mayo Clinic cancer specialist, Dr. Tim Moynihan. Dr. Moynihan practices in the Department of Medical Oncology at Mayo Clinic in Rochester, Minnesota. He's also a cancer medical editor for MayoClinic.com. Dr. Moynihan, thanks for being with us.

Dr. Moynihan: Thanks for having me, Rich.

Rich Dietman: To begin with, what exactly is adjuvant chemotherapy when it's used for cancer?

Dr. Moynihan: Adjuvant chemotherapy is something that's used after the primary treatment for the cancer, with the goal of trying to prevent that cancer from coming back. And the reason we use it, we do know people who, let's say, have an operation for removal of cancer, the surgeon will go in and remove everything that they can see, and as far as we know oftentimes all of the cancer has been removed. However, experience has taught us that some of those people have the cancer show up somewhere else in their body, somewhere down the road. So what we think happens is there must be some microscopic, tiny little bit of the cancer that has broken away and may be hiding in another part of the body. The idea is that we use the chemotherapy at that time to try and clean up that little microscopic bit that might be hidden somewhere. And in many kinds of cancer it actually does do the job and cleans things up and causes the cancer not to come back. It's not done in every situation and it's not perfect in every situation — sometimes you get the chemotherapy and the cancer still comes back — but for many situations it clearly decreases the chance of the cancer coming back.

Rich Dietman: So it's kind of an insurance policy?

Dr. Moynihan: That's one way to look at it, yeah, it may help increase your chances of cure, and in many situations it clearly makes people live longer, and again a higher chance that recurrence of your cancer never comes back.

Rich Dietman: Is adjuvant chemotherapy ever given before other kinds of treatment for cancer?

Dr. Moynihan: Absolutely it is and when we do that we often call it neoadjuvant chemotherapy, sort of given before the primary treatment. And that's used in several situations, particularly if the shrinking the tumor first might help make an operation or some other treatment easier. For example, we often use this in people with advanced breast cancer where an operation might be somewhat hard because the size of the tumor or the size of the woman's breast. If we can shrink that, it sometimes makes the operation easier for the surgeon and easier for the patient, and sometimes maybe more successful for them. And then we might also give some chemotherapy further after the operation too in an adjuvant setting to help again decrease the chance of it coming back.

Rich Dietman: Is adjuvant chemotherapy given in one particular form — intravenously, by pill — or is it given in different ways?

Dr. Moynihan: There's many different forms of chemotherapy. We try to be very specific with the chemotherapy, what's going to work best for that particular patient for their particular disease. So there are pill forms, there's intravenous forms, it's several different combinations that can be used, and it really depends on the specifics of the individual's case.

Rich Dietman: What factors are used to determine whether adjuvant chemotherapy might be helpful in treating a cancer?

Dr. Moynihan: The most important thing is to know: Is that cancer sensitive to chemotherapy? And what's our prior experience? Have we shown that giving chemotherapy in that setting improves the chances? If it is helpful to improve your chances, it may be worth the side effects you have to go through to get it. If however, on the other hand, it doesn't show that it improves anything, we probably shouldn't be doing it. So that's why it becomes an individual decision based on the type of cancer you have, your general health, how far the cancer's spread and what kind of cancer it is.

Rich Dietman: How do doctors go about determining whether adjuvant chemotherapy is going to be effective or not? You mentioned that obviously they know if a particular kind of chemotherapy has worked before, but are there other factors that come into play here?

Dr. Moynihan: What happens is we do very large studies in people. Usually if we know certain cancers may be sensitive to chemotherapy, we try to then move that chemotherapy up earlier in the course of the disease, and we do very large studies where half the people get a treatment, half the people don't get any treatment and see which group does better. If the people who get the treatment have a lower chance of the cancer coming back, then we know it's a useful treatment for them. We're trying to further individualize that down to individual patients by looking at factors in their blood or factors in their tumor and trying to predict, who is it specifically that really benefits from the treatment so we can really hone in and give the treatment only to those people who are going to get better from it.

Rich Dietman: If I've had cancer surgery and my surgeon believes that all the cancer has been removed, what I hear you saying is that there still might be a case to be made for adjuvant chemotherapy.

Dr. Moynihan: Yes, and often the surgeon will remove everything they can see and surgeons do a great job with that and they're wonderful doing that. Sometimes though, we know that little tiny microscopic bits of the cancer break off and hide in other parts of the body. And we can look at the factors associated with the tumor that are removed and when we look at it pathologically under the microscope and say that you may have a certain chance of this cancer coming back because of the way it looked. If that chance is relatively high, of it coming back, then giving chemotherapy to decrease that chance may be very worthwhile. If, on the other hand, the chance of that cancer coming back without chemotherapy is very, very, very, very low then there's really not much role for chemotherapy and there's not much reason to take the side effects of the chemotherapy.

Rich Dietman: So you know by looking at not only the type of cancer but what stage it was at, the characteristics of that particular cell or set of cells that was removed how it's likely to behave if it has broken away and gone elsewhere?

Dr. Moynihan: Exactly. We look at the characteristics under the microscope and see what the cancer looks like. We look to see how large the cancer is, has it spread to any lymph nodes? Has it invaded the tissues around where it originally started? And we're now actually starting to look at the individual genes within the cancer cells that may well predict the likelihood for it to spread or to be hiding in other parts of the body. This has been a very helpful tool. These are brand new tools that are still being evaluated, but are beginning to come into clinical use that will help tell us that person A needs chemotherapy and person B does not, to help their chances of survival.

Rich Dietman: Are there other forms of adjuvant therapies for cancer besides chemotherapy?

Dr. Moynihan: Absolutely. For some tumors that are sensitive to hormones, we may use adjuvant hormonal therapy. The most common forms of this are either breast cancer or prostate cancer, but there are other examples too where we may add a hormone blocking agent or some other alteration of the hormone system to help decrease the chance of the cancer coming back. In addition, you can use adjuvant radiation therapy. Now radiation therapy is a more local form of therapy — only treats the area around the tumor bed itself — but that may also help decrease the chance of the cancer coming back.

Rich Dietman: Is adjuvant chemotherapy most effective if it's given relatively soon after surgery? Or can a person delay?

Dr. Moynihan: Almost all the studies that we've done that have shown that adjuvant chemotherapy has been helpful have usually started the treatment somewhere between two to three weeks and eight weeks after the operation. So to delay much more than that, we don't know how much good it's going to do. We certainly wouldn't advocate delaying many months, but a short delay to allow healing time after the operation is very reasonable. Whether or not it does good to do it a year later, two years later, we don't think so. And there's no data that would support that, so we would not standardly recommend that at this time.

Rich Dietman: Thanks very much, Dr. Moynihan. We've been talking about adjuvant chemotherapy with Dr. Tim Moynihan, a cancer specialist at Mayo Clinic in Rochester, Minnesota, and cancer medical editor for MayoClinic.com. You've been listening to Mayo Clinic podcast. I'm Rich Dietman.

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