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  Drugs
employed in chemotherapy represent an heterogeneous group of substances
that inhibit the proliferation of malignant cells with different
mechanisms, mainly genotoxic. These do not spare normal highly
proliferating tissues (piliferous bulb, intestinal epithelium, bone
marrow).
The main groups of chemotherapic drugs include:
- alkylation agents (cyclophosphamide, cisplatinum, carboplatinum, ect.);
- antimetabolites (azathioprine, fluorouracil, methotrexate, etc.);
- antimitotics (vincristine, vinblastine);
- antibiotics (actinomycin, bleomycin, daunomycin);
- enzymes (L-asparaginase).
Most of these substances have been proved to be mutagenic, carcinogenic
and teratogenic in experimental systems.
Antineoplastic drugs usually irritate skin and mucous membranes. Furthermore,
they can provoke local toxic effects (phlebitis, allergies, tissue
necrosis) and systemic toxic effects (allergies, organ toxicity).
In the following table the local effect of the main antineoplastic drugs
in case of discharge(?) is indicated.
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Not blister
- Not irritants
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Irritants
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Blister
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L-Asparaginase
Bleomycin
Cyclophosphamide
Cytarabine
Methotrexate
Thiotepa
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Carmustine
Dacarbazine
5-Fluorouracil
Cisplatinum
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Daunorubicin
Doxorubicin
Epidoxorubicin
Etoposide
Mitomycin C
Mitoxantrone
Vinblastine
Vincristine
Vindesine
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Among the systemic toxic effects, toxicity on organ and apparatuses of
the treated patient must be mentioned.
Short term effects include alopecia, stomatitis, leucopenia and anaemia;
medium term effects are liver disease, nephrosis and bone marrow aplasia;
long term effects include the arising of a second tumour and myocardium
sclerosis.
Among the most serious side effects of these drugs there are both
mutation induction and carcinogenic effects. According to IARC
(International Agency for Research on Cancer) many antitumoural drugs can
provoke tumours. In fact, cases of second tumours in patients treated
with antiblastic drugs have been reported (especially acute non
lymphoblastic leukemia).
Antitumoural drugs taken into account by IARC are reported in the
following table:
Group 1: carcinogenic to humans
1,4-Butanediol dimethanesulfonate (Myleran)
Cyclophosphamide
Chlorambucil
1(2-Chloroethyl)-3(4-Methylcyclohexyl)-1-Nitrosourea
Estrogens
Melphalan
MOPP
Treosulfan
Group 2: probably carcinogenic to humans
sufficient evidence
Adriamycin
Bischloroethyl nitrosourea (BCNU)
Cisplatin
1-(2-Chloroethyl)-3-Cyclohexyl-1-Nitrosourea (CCNU)
Procarbazine hydrochloride
Thiotepa
limited evidence
Bleomycin
Dacarbazine
Daunomycin
As far as the potential exposure of the health workers is concerned, the
enormous difference between therapeutical doses and doses resulting from
professional exposure must be emphasized. Up to the present day reliable
carcinogenic effects have been found only in the treated patients and not
in health workers.
Cytogenetic effects, such as an increase in chromosomic aberrations and
exchange of sister chromatids have been shown in groups of nurses and
pharmacy personnel that had been handling the drugs without taking the
recommended precautions, whereas they have not been observed in the
groups that complied with the required hygienic measures.
As far as the potential effects of professional exposure to these drugs
on the outcome of the first three months of pregnancy are concerned, some
case-control studies have shown a double risk of miscarriages and
malformations on the offspring, whereas other more recent studies have
shown negative results.
For additional information
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