Has your surgeon or oncologist recommended adjuvant chemotherapy?
Are you unsure what adjuvant chemotherapy is and why it has been recommended?
Adjuvant chemotherapy is offered after you’ve had surgery. The adjuvant treatment is given to “mop up” any remaining cells that might be left in your body that could grow and require further treatment. If cells are present and grow, this is called a recurrence. The adjuvant chemotherapy is given as insurance against the possible presence and growth of the cancer cells. Adjuvant chemotherapy is given to treat any possible remaining cancer cells. After surgery not everyone will have cancer cells remaining. As there is no way of knowing whether cells are present or not, adjuvant chemotherapy is given to all patients – some of these will have cancer cells and some won’t.
While it might be argued that some patients who are offered adjuvant chemotherapy actually don’t need it, because we don’t know who they are, treatment is still offered to all.
The following scenario is offered as an example to explain the concept. It uses numbers or rates that are simple to understand. Your cancer will have different numbers for possible recurrence and response rates to adjuvant chemotherapy or hormone therapy.
You should ask your medical oncologist what the rates are for your cancer.
Hypothetical Scenario
Imagine a cancer in which the risk of recurrence without having adjuvant treatment is 60% (or 60 in each 100). That is, if 100 people undergo surgery for cancer and did not have adjuvant chemotherapy, 60 would experience a recurrence and 40 would not.
If adjuvant treatment is given, then 20 people who would have had a recurrence (and potentially could require long term chemotherapy) are cured. This adds to the 40 patients who were cured with surgery alone and did not need chemotherapy (40+20 = 60).
IF WE KNEW WHO HAS CANCER CELLS REMAINING AFTER SURGERY ADJUVANT CHEMOTHERAPY COULD BE GIVEN TO THEM ALONE
Of the 60 people who have cells remaining after surgery, 20 would be cured after adjuvant chemotherapy.
BUT WE DON’T KNOW WHO HAS ANY CANCER CELLS REMAINING AFTER SURGERY SO ADJUVANT CHEMOTHERAPY IS GIVEN TO EVERYONE.
Adjuvant chemotherapy increases the number of people cured overall.
Does that mean you should not have adjuvant chemotherapy?
- If we knew who was going to be cured by the surgery alone, we wouldn’t need to treat them with adjuvant chemotherapy (40 people).
- If we knew who was going to have their cancer recur and who would respond to adjuvant therapy, we would just target those individuals (20 people).
- If we knew who was going to have their cancer recur and not respond to adjuvant treatment, we would not give them adjuvant therapy and look at treatment options when their cancer recurred (40).
Unfortunately, little is known about who will benefit and who won’t so most people are encouraged to have adjuvant chemotherapy.
In time, it is possible that more information about how individuals respond to cancer treatments will become available and this will help in deciding who will benefit most from adjuvant chemotherapy. See below for examples of emerging information on ways to decide who might benefit for certain cancers.
Every cancer has its recurrence and cure rates and you are encouraged to discuss these issues with your oncologist.
If your cancer recurrence risk is low and you decide not to have adjuvant chemotherapy because of the side effects, it is important to understand that it may recur and at that time chemotherapy may be required. For many individuals whether or not to have adjuvant therapy comes down to how comfortable they feel with their decision and with the possibility (even if low) that their cancer may return if they decide not to have the treatment.
When adjuvant chemotherapy is used post-surgery, the number of cancer cells is often small.
Leaving treatment until a recurrence is diagnosed means that there are a large number of cells and chemotherapy treatment may not be curative. Adjuvant chemotherapy is usually given within a particular time frame for a given cancer (on the basis of Clinical Trials). Delaying adjuvant chemotherapy can mean that it is not as effective. That is the numbers given in the trial may not be as good as those published if there is a significant delay in starting treatment.
If these issues are unclear, I’m available to discuss the risks and benefits of adjuvant chemotherapy with you.
Emerging information on ways to decide who will benefit and not benefit from adjuvant chemotherapy (ctDNA & OncotypeDX)
Recent research is looking in to ways of knowing who will not benefit from adjuvant chemotherapy. Genomics and circulating tumour DNA, (ctDNA) may have an answer.
For some time, people with breast cancer have been able to access (for a price) a test called OncotypeDX. The results from the test allow oncologists to decide who might benefit from hormone therapy alone (low score) or who would be more likely to benefit from a combination of hormone therapy and chemotherapy (high score).
For the large group of patients with intermediate test scores little was known about the best treatment.
Because we did not know, these patients usually received the default option of having both chemotherapy and hormone therapy. Recently published data (2018) from the TAILORx study has shown that for patients with intermediate scores hormone treatment alone is non-inferior (or no different) to the combination of hormone therapy and chemotherapy. Thus, patients with intermediate scores can forgo chemotherapy and have hormone treatment alone, thus avoiding the need for chemotherapy entirely. At the moment the test is costly and it is hoped that access may eventually be provided through Medicare.
In colorectal cancer, a new trial (The DYNAMIC trial) is looking at recurrence rates in stage 2 and 3 colon cancer between those with ctDNA (circulating tumour DNA) and those without it. This study should help to define a group of patients with a high risk of recurrence who definitely should have adjuvant chemotherapy and those in whom chemo can be omitted or the dose reduced. This trial is recruiting in Australia and NZ. It may not be possible to be part of this trial, but results will be revealing. A variation of the trial is looking at the use of ctDNA in ovarian cancer.
If these issues are unclear, I’m available to discuss the risks and benefits of adjuvant chemotherapy with you.