AC
Meaning of AC: The same two letters name a shoulder joint, a ventilator mode and a dosing instruction, so the surrounding note decides which AC is meant.
Definition of AC
AC is a chemotherapy regimen that combines two drugs, doxorubicin and cyclophosphamide, given together on a repeating cycle. It is used most often in breast cancer. Both drugs damage the DNA inside dividing cells, but by different chemical routes, and pairing them is intended to kill more cancer cells than either drug achieves alone.
What do the two drugs do?
Doxorubicin is an anthracycline. It slots between the paired strands of DNA and jams an enzyme the cell needs to unwind and copy them. Cyclophosphamide is an alkylating agent, which attaches chemical groups to DNA and welds the two strands together so they cannot separate. Cells that divide fastest suffer most, which is the point of the pairing but also the source of its effects on normal tissue that renews quickly, such as bone marrow, hair follicles and the lining of the gut. Doxorubicin carries a further consideration: injury to heart muscle that accumulates with the total amount given across a lifetime, which is why that running total is recorded. Cyclophosphamide can irritate the bladder lining, so fluids are given alongside it.
How is the regimen given?
The AC regimen is delivered by infusion into a vein, in cycles spaced to let blood counts recover between doses. In breast cancer it is frequently followed by a taxane drug, and it may be given before surgery to shrink a tumor or after surgery to reduce the chance of return. Shorter intervals between cycles, supported by a growth factor that speeds white cell recovery, are one recognized variation on the schedule.
What else does AC stand for?
| Setting | What AC means |
|---|---|
| Oncology | Doxorubicin plus cyclophosphamide chemotherapy |
| Orthopedics | Acromioclavicular joint, where the collarbone meets the shoulder blade |
| Critical care | Assist control, a mode of mechanical ventilation |
| Prescriptions | Ante cibum, Latin for before meals |
Nothing in the letters themselves separates these meanings, so the specialty writing the note is the reliable clue. An AC written beside a dose and a mealtime is not the same AC written in a chemotherapy plan.
Also known as
Used in a sentence
The oncology note documented that the patient was starting AC chemotherapy prior to a planned course of radiation.
Good to know
The abbreviation AC depends heavily on context, since the same two letters can mean a chemotherapy regimen, a shoulder joint, a ventilator setting, or an instruction to give a dose before meals.