We read with interest the report by Brassat et al. [1] describing the
development of acute myeloblastic leukemia (AML) in a young woman
following treatment of MS with mitoxantrone. The authors presented
adequate evidence to reasonably support their conclusion that AML in this
case occurred as a “therapy related acute leukemia.” The authors also
discussed the rarity of this occurrence and were able to reference only
one other similar case. All of this not withstanding, the authors did not
mention that MS has been associated with various types of leukemia in
various other treatments [2, 3, 4, 5]. This group of cases taken together
might tend to suggest an occasional association of leukemia with MS itself
rather than an association of leukemia with mitoxantrone or with any of
the particular therapies reported. This group of cases may also be a
bridging point between two other groups of cases, both of which report an
association between malignancy and demyelination in the CNS.
In one group [6, 7] colon carcinoma is treated with 5-fluorouracil (5
-FU), an antineoplastic antimetabolite, together with levamisole, an
immunomodulator, as adjuvant therapy, and this is occasionally followed by
the discovery of demyelinating lesions of the brain. The brain
demyelinating lesions in all cases are considered to be caused by 5-FU and
levamisole, although an observational bias is possible since a high
percentage of patients with colon carcinoma were treated with 5-FU and
levamisole, and a relatively small number of patients with subsequent
brain demyelination have been reported. Recently leucovorin has been used
with 5-FU in adjuvant therapy of colon cancer, yet no cases of brain
demyelination have been associated with this combination.
In the other group, involving seminoma, there has recently been
speculation regarding the possibility that demyelination in the brain may
occasionally occur as a paraneoplastic disorder. A few cases referenced
elsewhere [8] have generated interest in this possibility and various
patterns of brain demyelination have been described. None of these cases
has mentioned a therapeutic agent as playing a causal role in either brain
demyelination or malignancy.
Considering these three groups together may be essential to
eventually solving the many problems presented by each. In the leukemia
group, CNS demyelination may [1, 5] or may not [3, 4] precede malignancy,
and a variety of therapies are utilized in these cases. In the colon
cancer group, brain demyelination typically follows malignancy and is
associated entirely with specific therapeutic agents. In the seminoma
group, neither malignancy nor brain demyelination is associated with
therapeutic agents.
We speculate that some cases of brain demyelination may occur as a
paraneoplastic disorder associated with various malignancies. The
etiology, scope, and other specific details of this phenomenon currently
remain obscure. We further speculate that some pharmaceutical agents may
play a potentiating role in causing such brain demyelination but that a
necessary, if not sufficient (in the case of colon cancer), causal role
may be played by the presence of malignancy. Cellular and clinical data
both suggest that levamisole may be capable of playing such a potentiating
role.
In the case of Brassat et al. we speculate that MS may have occurred
prior to leukemia as a paraneoplastic disorder, and that mitoxantrone may
have played no role in causing leukemia.
References:
1.Brassat D, Recher C. Waubant E, et al. Therapy-related acute
myeloblastic leukemia after mitoxantrone treatment in a patient with MS.
Neurology 2002;59:954-955.
2.Hilbe W, Berger T, Konwalinka G, et al. Cladribine treatment of a
patient with hairy cell leukemia and concomitant multiple sclerosis. Acta
Haematol 1999;102:99-100.
3.Kataoka I, Shinagawa K, Shiro Y, et al. Multiple sclerosis
associated with interferon-alpha therapy for chronic myelogenous leukemia.
Am J Hematol 2002;70:149-153.
4.Saito N, Tanaka T, Matsuda S, et al. [A case of inflammatory
demyelinative myelopathy after bone marrow transplantation]. Rinsho
Shinkeigaku 2000;40:556-560.
5.Meloni G, Capria S, Salvetti M, et al. Autologous peripheral blood
stem cell transplantation in a patient with multiple sclerosis and
concomitant Ph+ acute leukemia. Haematologica 1999;84:665-667.
6.Mak W. Cheng PW, Cheung RTF. Leukoencephalopathy following
chemotherapy for colonic carcinoma. Clinical Radiology 2001;56;333-335.
7.Savarese DM, Gordon J, Smith TW, et al. Cerebral demyelination
syndrome in a patient treated with 5-fluorouracil and levamisole. The use
of thallium SPECT imaging to assist in noninvasive diagnosis—a case
report. Cancer 1996;77:387-394.
8.Jaster JH, Dohan FC Jr, O’Brien TF. Demyelination in the brain as a
paraneoplastic disorder: candidates include some cases of seminoma and
central nervous system lymphoma [letter]. J Neurol Neurosurg Psychiatry
2002;73:352.