TAC
Meaning of TAC: Three chemotherapy drugs given together for breast cancer, the letters taken from their older trade names.
Definition of TAC
TAC is an abbreviation for a chemotherapy combination of docetaxel, doxorubicin and cyclophosphamide, given together for breast cancer. The three letters come from the drugs' brand or older names: Taxotere, Adriamycin and Cytoxan. It is delivered in cycles, most often after surgery, to lower the chance that the cancer comes back.
What is in the combination?
| Letter | Drug | How it acts |
|---|---|---|
| T | Docetaxel | Freezes the scaffolding a cell needs to divide |
| A | Doxorubicin | Jams the machinery that unwinds and copies DNA |
| C | Cyclophosphamide | Links DNA strands so they cannot separate |
Each attacks cell division at a different point. Combining them raises the chance that a cell resistant to one drug is caught by another, and it spreads the toll across different tissues rather than concentrating it in one.
Why give chemotherapy after surgery?
Removing a tumor deals with what can be seen. Cells that left before the operation are too few to show on any scan, and those are what cause a relapse later. Chemotherapy given after surgery, called adjuvant treatment, is aimed at them. Whether it is offered depends on features of the tumor that predict how likely such spread is, including size, involvement of lymph nodes, grade and receptor status. The same drugs are sometimes given before surgery instead, which shrinks the tumor and shows directly how well the disease responds.
What side effects does it carry?
The regimen is one of the harder ones. Falls in white cell count are severe enough that an injection to protect the bone marrow is given alongside it as a matter of routine. Hair loss is close to universal. Nausea, mouth soreness, deep fatigue and tingling in the hands and feet are common. Doxorubicin can weaken heart muscle, so heart function is measured before treatment starts and a limit applies to the total lifetime amount a person can receive. Fertility may be permanently affected, which is discussed before treatment begins in anyone who might want children later.
Is it still used?
It is one option among several. Breast cancer treatment has become far more tailored, guided by hormone receptor status, HER2 status and gene expression tests that estimate how much benefit chemotherapy will add. Regimens without an anthracycline such as doxorubicin are now preferred in many situations, particularly where heart risk is a concern.
Also known as
Used in a sentence
Adjuvant treatment consisted of six cycles of TAC with marrow growth factor support.
Good to know
The doxorubicin component can weaken heart muscle, so heart function is measured beforehand and a lifetime limit applies to the total amount given.