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Chemotherapy drugs are designed to kill off any (and all) rapidly-dividing cells. That’s not entirely true; it’s more a short-hand way of getting the point across.
Why Chemotherapy Seems To Target Speedy Cells
In principle, chemo agents would kill every cell, healthy or not, once it’s reached a specific point in cellular division. Some drugs short-circuit a cell’s ability to copy its own genetic material, while others prevent the process by which cells actually divide in two. But most of the time, the cells in your body just aren’t dividing very much. That’s why it looks like chemo agents target rapidly-dividing cells, but avoid others, because cells that divide more often are targeted more often.
That category certainly includes cancer cells, but it also covers also healthy tissues, especially ones that are vulnerable to injury and need to divide quickly to repair damage:
- bone marrow,
- skin cells and
- intestinal lining.
Where side effects are concerned, chemo often causes diarrhea and oral sores, because it’s wearing away at intestinal cells, along with decreases in white blood cells, which are produced in bone marrow.
Hair Grows Fast, & Alopecia (Often) Follows
Of course, we’re all most familiar with the effect chemo agents have on hair follicles, which divide every 23 to 72 hours. That’s fast, at least in terms of the cells inside human adults. Bacteria are even more extreme, undergoing “mitosis,” the process of cellular division, in under 20 minutes. The cells of which fetuses are made, along with those in young non-human animals, divide pretty quickly, too, before slowing down upon maturity.
Assumedly, chemotherapy would tackle all of these tissues in the same way: search and destroy. Chemo agents just don’t discriminate between cancers and healthy tissues. But contrary to popular belief, many chemo drugs don’t actually cause all of the side effects you’d expect after figuring out how they work.
Some Chemo Drugs Rarely Cause Hair Loss
In fact, many chemo drugs don’t cause hair loss, which is certainly the side effect most closely-associated with chemotherapy. Perhaps even more surprising, only a minority of the chemo drugs used to treat breast cancer cause hair loss in most patients. Out of the 11 most common chemotherapy agents used for breast cancer patients, only 5 lead to alopecia in a majority of people.
Hair Loss In 11 Common Breast Cancer Drugs
We’ve ranked these drugs according to how likely they are to cause hair loss, as demonstrated in clinical trials:
- Doxorubicin (Adriamycin) : between 60% and 100% of patients
- Paclitaxel (Taxol) : around 87% of patients
- Docetaxel (Taxotere) : up to 74% of patients
- Epirubicin (Ellence) : between 69% and 96% of patients
- Cyclophosphamide (Cytoxan) : more than 60% of patients
- Carboplatin (Paraplatin) : between 43% and 50% of patients
- Fluorouracil (5FU) : between 10% and 50% of patients
- Vinorelbine (Navelbine) : between 12% and 30% of patients
- Gemcitabine (Gemzar) : between 15% and 18% of patients
- Cisplatin (Platinol) : a little more than 10% of patients
- Capecitabine (Xeloda) : around 6% of patients
It’s not, however, simply a misconception that’s come to link breast cancer treatment and hair loss in the public’s perception.
Doubling, Or Tripling, Up
Over the last few decades, doctors have turned from using these drugs on their own to a different practice, of combining various chemo agents together in ever-more-complex multi-drug “regimens.” The idea is to attack cancer cells in multiple ways at once, while throwing tumors, which can evolve to become resistant to chemotherapy, continually off balance. But generally, when you put two or more chemo drugs together the risk for hair loss increases. Alopecia is a common result.
In recent years, the trend toward multi-drug regimens has dropped off a bit, with several monotherapies (capecitabine, with a 6% risk of hair loss, being one of them) having been proven remarkably effective on their own. But it wouldn’t be out of line to suggest that combination therapies are still the most common, although there are few statistics to substantiate this point firmly.
Is Permanent Hair Loss Even Possible?
Since chemotherapy is, for many patients, the only hope for survival, hair loss is often a side effect people are willing to live with. But it can be traumatic. Beyond the consequences you would expect, like lower self-esteem, researchers have found that breast cancer patients who experience hair loss have a harder time performing basic reasoning tasks. What’s more, a majority of people who go through hair loss deal with life-long esteem issues as a result.
Thankfully, hair loss itself is usually temporary, and most chemotherapy patients can expect regrowth within three to four months after finishing treatment. That assurance has only been questioned in the case of one breast cancer drug, Taxotere, which has been linked to a risk of permanent, irreparable alopecia.