Breast cancer sometimes recurs after treatment. A new study suggests that in part,
the answer may lie in the effect of adjuvant hormone therapy on some cancer cells.
Doctors usually recommend hormone therapies for the treatment of estrogen
receptor-positive breast cancers, in which the cancer cells grow and spread by
interacting with a hormone called estrogen. Typically, a course of hormone therapy
follows surgery for tumor removal, and while this strategy is successful in many
cases, some people experience a relapse. This can lead to metastasis — a state in
which cancer cells spread throughout the body, making it more difficult for doctors
to spot and treat. "This strategy significantly delays clinical relapse but does not
abrogate it completely, as about 3% of the patients each year come back with overt
relapse, inevitably leading to further metastatic development the researchers write
in their study paper.
In the study, Magnani and colleagues found that while adjuvant
hormone therapy did indeed kill most of the cancer cells they exposed to it, it only
sent some cancer cells into a dormant state. They [the sleeper cells] could then
'awaken' once in other organs of the body and cause secondary cancers. However,
we still don't know how these cells switch themselves into sleep mode — and what
would cause them to wake up. These are questions that need to be addressed with
further research", says Dr. Sung Pil Hong. “Although treatments for breast cancer are
usually successful, cancer returns for some women, often bringing with it a poorer
prognosis. Figuring out why breast cancer sometimes comes back is essential to help
us develop better treatments and prevent this from happening. This study highlights
a key route researchers can now explore to tackle 'sleeping' cancer cells that can
wake up years after treatment, which could potentially save the lives of many more
women with the disease”, notes Dr. Shaw.
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