Be prudent of ketamine in treating resistant depression in patients with cancer.

Yang C, Zhou ZQ, Yang JJ

Chun Yang, M.D., Zhi-qiang Zhou, M.D., Ph.D., and Jian-jun Yang, M.D., Ph.D.
Dear Editor:
Pain, suffering, hopelessness, loneliness, and fear of death are
the main contributing risk factors to the development of depression
in patients with cancer.1 Antidepressants are intended
to improve patients’ mood status and alleviate depression.
Unfortunately, conventional antidepressants, such as imipramine
and fluoxetine, cannot effectively ameliorate the symptoms
of refractory depression in some patients with cancer.
Ketamine as a classic anesthetic agent has often been used
during anesthesia for pediatric operations. Latest data have
suggested that a subanesthetic dose of ketamine has robust
and rapid therapeutic effects in the treatment of depression,
especially for patients who are resistant to conventional antidepressants.
1–3 Thus, ketamine has the potential to be an
innovative antidepressant, which is different from the conventional
antidepressants that exert antidepressant effects via
the inhibition of the monoamine transmitter transporter in
presynaptic membranes.
However, a recent study has revealed that the underlying
mechanism of the antidepressant effects of ketamine is principally
due to the up-regulation of mammalian target of rapamycin
(mTOR).4 This study suggests that the signaling
pathways of rapid activation of mTOR is a novel strategy for
the rational design of a fast-acting antidepressant.4 However,
the up-regulated mTOR may cause the acceleration of tumor
growth.5 Therefore, further studies involved in patient prognosis
are needed to investigate whether ketamine is suitable
for the treatment of refractory depression in patients with
cancer.