Understanding your chemo regimen

This is my first “non-chemo Wednesday” since I started the first of my eight fortnightly sessions on 19 August. It therefore seems appropriate to post a piece about the chemotherapy regimen I was on.

People had all sorts of questions about my treatment. Why are you having chemo every two weeks instead of every three? Why are you having it before surgery instead of after? How do they decide which drugs to use? I had exactly the same questions… and many more besides. After much questioning of my oncologist and much online research, I think I’ve got the answers. This all gets a bit technical, but if you like detail, do persevere.

I was on a dose-dense, neoadjuvant (ie pre-operative) chemotherapy regimen that involved a drug combination known as AC-T. The acronym is made up of the initials of the drugs. The regimen comprised four fortnightly sessions of Adriamycin/doxorubicin & Cytoxan/cyclophosphamide in combination followed by four fortnightly sessions of Taxol/paclitaxel on its own. The words that start with a capital are the brand names and the words that follow are the active ingredients, in the same way as Neurofen is a brand or make of ibuprofen.

I had my eighth and final chemo session two weeks ago today, on 25 November (“Well done, Maureen”, “#8 Final” and I’m off the chemo leash).

Combinations and series of treatments

On the question of why certain drugs are given in combinations, chemotherapy damages cells as they divide and so combinations include drugs that damage cells at different stages in the process of cell division. Doxorubicin and paclitaxel are among the most common chemo drugs used for early breast cancer and they’re often used in combination with cyclophosphamide.

In addition, using regimens with combinations of chemotherapy that work differently increases the cancer cell kill by changing how the cancer is attacked. Also, combinations usually use drugs with different side-effect profiles. By combining different drugs, oncologists try to minimise toxicity. Too much doxorubicin can cause heart damage and too much paclitaxel can cause nerve ending damage.

Treatment is unlikely to kill every single cancer cell in the body, but chemotherapy (and/or radiotherapy) aims to reduce the numbers of cancer cells to such an extent that the remaining cells will be killed off by the body’s own defences or will die off naturally. Not all the cells in a cancer divide at the same time and giving chemotherapy in a series of treatments helps to attack as many cells dividing as possible and so kill them. Cells that were inactive during your first treatment may be active when you have the next, and so on with each session.

After all the hospital-based treatment (chemo, surgery, radiotherapy), I’m to go on long-term hormone therapy. Hormone treatment after chemotherapy in oestrogen-positive tumours (as mine is; indeed, most are) is designed to defend against any quiet or sleepy slow-growing survivor cancer cells. These can be starved by the lack of oestrogen and thus often don’t reactivate and grow because the host, ie the woman, by providing no or low oestrogen, is very unwelcoming. These potential dormant cells need to be starved for many years to give the woman the best chance of remaining free of active cancer. This is why hormone treatment in one form or another is now recommended for some women for ten years.

Dose dense

“Dose dense” means having the doses of chemo more closely together than is the norm, in my case every two rather than every three weeks. In some studies this has been found to lower the chance that the cancer will come back and improve survival in some women. Others, however, say there is very little to choose between the two approaches on this front.

Overall this dose-dense approach is seen as being slightly gentler on patients than longer regimens. For a start you’re in chemo for less time overall. In my case, you have eight sessions over 16 weeks as opposed to six sessions over 18 weeks. Another advantage is that since, at least in my case, the doses in the dose-dense regimen are slightly lower than they would be under a 6 x 3-week regimen (which in my case would have involved different drugs), the side effects may not be so severe. The downside is that you have less recovery time between sessions; they whack with the following session after just two weeks. A lot of people feel more or less normal during that third week in the longer regimen so you miss out on that week of respite. That might matter if, say, you really had to keep working while you were undergoing chemo. I was hugely fortunate in that I didn’t have to.

consentOne possible – but rare – severe side effect of dose-dense AC-T chemotherapy may be an increased risk of leukaemia or preleukaemia. Leukaemia is a known risk anyway in patients taking cyclophosphamide or doxorubicin, regardless of whether they’re on a dose-dense regime or not. While it’s stressed that the benefits of chemo in preventing breast cancer from coming back or in extending life are likely to far outweigh the risk in this regard, it really is quite astonishing what you agree to when you sign the consent form for treatment.

Neoadjuvant

As for having chemo before rather than after surgery, I’ve been told that the expectation is that in breast cancers such as mine this approach ultimately will be shown to help stop the cancer coming back and so improve long-term survival rates. There’s no evidence for this yet, but I’m keeping my fingers crossed.

Neoadjuvant chemo is given as standard to women whose tumours are too big to be operable in the hope that it shrinks the tumour sufficiently to make it operable; while mine was big, it was always operable.

A known benefit of giving chemo before the tumour is removed is that you can see how the cancer responds – or not – to the drugs that are being given. With me, we know the drugs worked well (An “excellent response to treatment”More good news, & Why my oncologist “couldn’t be happier”).

The final benefit of having chemo before surgery relates to whether you’re having breast reconstruction at the same time as your mastectomy, as I am. If you’ve had immediate reconstruction and need chemotherapy after your surgery, wound infection can be a problem as chemo can’t start until any infection you might have is cleared up and the wound healed. Having had the chemo beforehand eliminates this problem.

That’s it. I think I’ve finally got it in terms of understanding the ins and outs of my particular regimen. I hope you all have too.

 

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