Why you might need chemotherapy after surgery: the basics of adjuvant chemotherapy

Why you might need chemotherapy after surgery: the basics of adjuvant chemotherapy

What is adjuvant therapy?

One of the most common questions I hear at an initial visit, as a medical oncologist, is:

“My surgeon told me she got all the cancer.  So why am I here?”

One of the jobs of the medical oncologist is teaching our patients that cancer is a systemic disease.

That means even though it started in one part of the body, there can be cancer cells in other places of the body.  That can go undetected for months or even years before they cause a problem.

There are therapies that we can offer, called adjuvant therapies, that can decrease the chance that those cells can grow into new tumors months, and yes, even years, later, what is called metastatic disease.

First, some definitions.

  • “Adjuvant” = any therapy given after surgery to increase the chance of being cured after surgery.  This can include chemotherapy, radiation therapy, endocrine (hormonal) therapy, and immunotherapy.
  • “Cure” = living out the rest of one’s life cancer-free and dying of something other than cancer.  (You will note that this definition means we cannot say whether one is “cured” at any timepoint prior to death from another cause.  Rather, we can estimate the likelihood one is cured.)
  • “Metastases” = sites of cancer that have grown outside of the initial origin of the cancer.  This can be confusing.  I like to explain to my patients that cancer is always “named” for the site of origin.  One example is breast cancer.  If breast cancer metastasizes, (or travels, spreads), to the bone, it is not “bone cancer.”  It is breast cancer, metastatic to bone.  How do we know this?  Because if we did a biopsy, and the pathologist identifies the cells under the microscope, they are breast cancer cells, not bone cancer cells.
  • “Cancer-free” = the assumption that there is no remaining or active cancer in the body.
  • “Remission” = the best evidence suggests no evidence of remaining or active cancer in the body.

Confused yet?  Let’s use a (hypothetical) example to try to make it more clear.

Ms. Smith is a 55 year old woman who went in for her yearly mammogram and an abnormality was found in her left breast.  Fortunately, it was small, but a biopsy showed it was cancerous.  She was referred to a surgeon who sat down with her and explained her two options for surgery, mastectomy (removal of the entire breast tissue), or breast-conserving surgery, also called “lumpectomy” (removal of only the tumor and a small portion of the breast surrounding it).  Mrs. Smith would like to preserve her breast, but she is afraid that if she does not have mastectomy, she will have a lesser chance of cure.

Her surgeon explains that if she chooses lumpectomy, it will be recommended to have adjuvant radiation therapy afterward, and that if she completes this, she has the same chance of cure as someone in the same situation who chooses mastectomy.  Huh?  Ms. Smith is confused.  Let’s break it down to explain why:

  1. Over several decades, it was proven that more and more aggressive, extensive, and disfiguring breast surgeries, did not impact the long-term cure rates for breast cancer.  i.e., even women who had extensive removal of tissue under and around the breast, including muscle –“radical” mastectomy — still had metastatic recurrences of breast cancer months to years later, to the surgeons’ dismay.  Ultimately, surgeons realized that breast cancer is not just a disease of the breast. If breast cancer cells have metastasized, or ‘escaped’, into the body, BEFORE the surgery, it does not matter how extensive the mastectomy is, the cancer can recur months to years later, because those cells can hide in other tissues (such as bone, bone marrow, liver), and grow new tumors months to years later.  (For an elegant in-depth discussion of the history and evolution of breast cancer surgeries, I highly recommend the book “The Emperor of All Maladies,” by Siddhartha Mukherjee.  Don’t be put off by the size of the book, it is highly readable.  It was also made into a documentary series by PBS).
  2. Once this reality gained widespread acceptance, surgeons instead turned to doing SMALLER surgeries. To summarize many decades of research, the current standard of care is that a lumpectomy need only remove enough tissue to show (to the pathologist, under the microscope), that there are no cancer cells at the margin (the edge of the tissue that has been removed), and that if then paired with adjuvant radiation therapy, will have equal long-term survival rates as mastectomy.  Please note, this is key, PAIRED WITH RADIATION.  I sometimes meet patients who choose a lumpectomy, but then tell me afterward they are not going to choose the radiation.  Unfortunately, that is not how it works.  I tell my patients, IF YOU CHOOSE LUMPECTOMY, THAT MEANS YOU ARE CHOOSING ADJUVANT RADIATION.  They go together, we do not consider it optional.  (one possible exception would be a woman over age 70 with a small tumor with no high-risk features, but again that is a discussion that needs to happen between the woman and her surgeon, radiation oncologist, and medical oncologist).
  3. Whether Mrs. Smith chooses mastectomy, or lumpectomy with radiation, she will need to meet with a medical oncologist after surgery, to review her risk of future recurrence, and whether she needs adjuvant medical therapies. Let’s continue the story to illustrate this better:
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Ms. Smith is relieved by the information and chooses lumpectomy with adjuvant radiation therapy.  (As an aside, I should mention that not all breast cancer qualifies for lumpectomy – this should always be a discussion between a woman and her surgeon – but some factors that can disqualify a woman from being a candidate from lumpectomy can include (and are not limited to) a very large tumor and/or more than one tumor in the breast).

She does well with surgery, and at her post-op visit, her surgeon explains that she “got it all” and the “lymph nodes are clear.”  Ms. Smith is relieved and prepares herself for the next step of her post-lumpectomy radiation, but then she is alarmed and confused when her surgeon recommends, and sets up a consultation with, a medical oncologist.

The first thing she says to the medical oncologist is, “My surgeon said she got it all, so I don’t even know why I’m here.”

Here’s what I tell my patients:

Breast cancer, like most all cancers, is tricky.  It can be sneaky.  Even small tumors, not in the lymph nodes, (stage I), have a small risk of recurrence over time.  For hormonally sensitive breast cancer (often referred to as “ER – positive”, ER = estrogen receptor), this risk persists for life.  (A recent NEJM meta-analysis of over 60,000 women with breast cancer sheds more evidence on this).  I tell my patients that I do not tell them this to frighten them, but to empower them to make the best medical decisions for themselves.

I would explain to Ms. Smith that taking a pill medication with overall low rate of side effects once per day for the next 5 years would lower her risk of the breast cancer coming back by about 50%, and lower the risk of dying from breast cancer by 30%.  I would also explain that it is not a guarantee; unfortunately a small number of women could still relapse, and even die from breast cancer, despite taking the anti-estrogen pill.  Our job as medical oncologists is to advise our patients when they are in a high enough risk group of that happening, that taking several months of chemotherapy after surgery (adjuvant chemotherapy) would be “worth it” to lower their risk. (i.e. the potential life-saving benefits outweigh the potential risks of treatment).

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Historically, the main predictors of risk of relapse and metastases were anatomic – the size of the tumor and whether or not there are cancer cells in the lymph nodes.  More and more however we are learning that the risk is not always tied to anatomic features – sometimes cancers can be small in size, but aggressive in behaviour – and again, it is our job as medical oncologists to analyze and interpret the findings of the pathology report to advise our patients.

Ms. Smith is relieved to learn her risk of recurrence is overall low, but upset to hear that the risk is not zero.  She wants to know why there isn’t a scan or blood test that could be done to determine if she needs chemotherapy.

This is a great question, and there is quite a bit of research working on a blood test, but that is likely still years away.  In the meantime we do have some risk-stratifying tests that can be run on the tumor tissue (beyond the scope of this post – I think I’ll have to devote another post just to this topic), and we, as medical oncologists, will advise our patients when we think those tests should be done.

But as for scans, they will not help us, as we are talking about treating microscopic cancer cells — not possible to see on CT scans or PET scans. (or MRI, or ultrasound, or any other imaging test).

So to conclude the story:  Ms. Smith and her medical oncologist decide together that her breast cancer is in a low enough risk group that she would not necessarily benefit from chemotherapy.  She proceeds to her radiation therapy treatments, and when they are completed, she will return to her medical oncologist to start her endocrine adjuvant therapy (the anti-estrogen pill).

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While this example focused on breast cancer, we have these same discussions every day with patients with almost all other types of cancer after surgery.  For each person, we use all the available clinical data to make a risk assessment, but we also take into account each person’s age, health, level of function, living situation, goals, and support system, before making a recommendation.  This is what we mean when we say we individualize the cancer care.  Expect this visit to last 45-60 minutes (or even longer), and believe that your oncologist has spent already that same amount of time, or more, analyzing your case, and talking with your surgeon.

If you are reticent to meet with a medical oncologist, I hope this article will help change your mind.  At the least, try to go into the appointment with an open mind.  Even if it is not the news you want to hear, if your medical oncologist recommends adjuvant treatments, they are doing so with your best long-term interests in mind, which is to give you the best chance of cure.

Disclaimer:  This is by no means an exhaustive coverage of this topic (which would be impossible to do in under1800 words), nor is this meant in any way to be used as medical advice.  Please see full site disclaimers on the about me page.

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