Risk of leukaemia associated with cancer chemotherapy

[Health risks of occupational exposure to anticancer (antineoplastic) drugs in health care workers]

In Europe and America, many health care workers have concerns about the risks to their health of handling anticancer drugs. The findings of the risks were reported in the late 1970's, and guidelines for the safe handling of anticancer drugs were established in the 1980's. The conditions of wearing personal protective equipment and of the working environment have improved dramatically as a result of introduction of the guidelines. Furthermore, researches and studies into the health effects of occupational exposure to anticancer drugs have been pursued actively. In Japan, the society of hospital pharmacists established guidelines for the safe handling of anticancer drugs in 1991. Since then, mainly nurses have been concerned about the safe handling of anticancer drugs, but in the medical setting, the present situation surrounding the safe handling of anticancer drugs has hardly changed. In the industrial hygiene field, the safe handling and the occupational exposure to anticancer drugs have been seldom reported and researched. The actual potential hazards to occupational exposure of anticancer drugs have not yet been determined. Nevertheless, the reduction of occupational exposure to anticancer drugs in health care workers has been an important challenge for the industrial hygiene field. In Japan, we need to promote action to spread the use of the appropriate personal protective equipment and the appropriate working environment. We also have to rethink the safe handling of anticancer drugs. We hope that the Japanese government will establish an effective authorized guideline as has been done in Europe and America.

Monitoring of occupational exposure to cytostatic anticancer agents

Many anticancer agents have been shown to be carcinogenic, mutagenic and teratogenic in experimental animals and in in vitro test systems. Epidemiological data on the association of second neoplasms with a specific chemotherapy treatment is available on some 30 agents, and in the case of 10 compounds the overall evidence on human carcinogenicity has been evaluated to be conclusive (Group 1: IARC, 1987 and 1990). The primary source of human exposure to anticancer drugs is from their use in therapy of cancer. However, persons employed in the manufacture, preparation and administration of the drugs to patients and in nursing patients may also be exposed. Safe handling of anticancer drugs, since the introduction of various general handling guidelines, is now good practice in hospitals, pharmacies and drug manufacturing companies of most developed countries. Careless handling of cancer chemotherapeutic agents may lead to exposure of the personnel in amounts detectable with chemical or biological methods in the body fluids or cell samples of the subjects. The exposure is typically to mixed compounds over long-term and to low exposure levels with accidental peaks. Therefore, the use of biological exposure markers is appropriate for the monitoring of such exposure patterns. The biological markers/methods for exposure assessment are either non-specific (e.g., cytogenetic damage, point mutations or 32P-post-labelling adducts in peripheral blood lymphocytes, urinary mutagenicity) or specific for a given compound (immunological methods for DNA adducts, specific analytical methods). Studies have revealed minor amounts of cyclophosphamide in the urine of pharmacy technicians and nurses handling the drug even when taking special safety precautions (Sessink et al. (1994a) J. Occup. Med., 36, 79; Sessink et al. (1994b) Arch. Env. Health, 49, 165). Another study showed surface wipe samples with measurable cyclophosphamide even away from the handling site (McDevitt et al. (1993) J. Occup. Med., 5, 57). These studies strongly implicate the importance of skin absorption as an exposure route. Also accidental spillage is never completely avoidable (Sorsa et al. (1988) Mutation Res., 204, 465-479). The potential confounders (smoking etc.), toxicokinetics of the agent(s) to be assessed and individual working practices should be carefully considered in any exposure assessment studies using human body fluid samples. Environmental monitoring on indicator cytostatics should be combined into studies designed to identify potential occupational exposure situations to anticancer agents. A properly performed study should also include dissemination of information to the workers to create a psychologically positive atmosphere for this important work.

An evaluation of the effectiveness and safety of razoxane when used as an adjunct to surgery in colo-rectal cancer. Report of a controlled randomised study of 603 patients

A prospective controlled randomised trial to evaluate the effectiveness and safety of razoxane is reported. Some 603 patients with colo-rectal cancer having curative surgery entered the study, and all have been followed up for a minimum of five years. Statistical analysis showed that razoxane treatment had no effect either beneficial or adverse on the rates of recurrence or on five year survival of patients with colo-rectal cancer. It is possible that a more prolonged course of razoxane might have significantly influenced survival. The incidence of severe adverse reaction was low but it is of concern that one patient developed leukaemia. Should razoxane be considered for future use it is recommended that continuous low dose therapy be given for no longer than 12 months. No renal, hepatic, pulmonary or cardiac toxicity was noted.

Safety considerations in somatic gene therapy of human disease with retrovirus vectors

Somatic gene therapy of human disease with retrovirus vectors is a new technology with potentially important medical benefits. Although it involves recombinant DNA technologies and modified retroviruses, proper design of the vectors and delivery systems removes most potential foreseen risks. Furthermore, even in the very remote possibility that there is a nontherapeutic biological effect of the treatment, it is unlikely to be a harmful one. Thus, once very safe retrovirus vector-helper cell systems are constructed and in use, safety considerations should not hold up further human trials of retrovirus vectors.

Lymphoid leucaemia in a dog after chemotherapy for mast cell sarcomas

A 10-year-old Golden Labrador developed a well-differentiated lymphoid cell leucaemia during chemotherapy for a malignant mast cell tumour. Similar treatment had been carried out 2 years previously for another mast cell tumour. The possibility of an association between the anti-neoplastic chemotherapy and the lymphatic leucaemia is discussed.

Double autologous bone marrow transplantation for acute myelogenous leukemia in a patient treated for Hodgkin's disease

A 30-year-old man developed acute myelogenous leukemia nearly 3 years after treatment of Hodgkin's disease with radiation and three chemotherapy combinations. Remission was induced with one cycle of high-dose Ara-C therapy. Three cycles of consolidation chemotherapy were given. The patient then had two autologous bone marrow transplants, the first after conditioning with 5 Gy total body irradiation, the second after Melphalan 140 mg/m2. The procedures were well tolerated, although hematological reconstitution was very slow after the second autotransplant. The patient has been disease-free for over 4 years. Such patients may be more vulnerable to transplant-related complications because of their previous exposure to chemotherapy and radiation, which may damage several organs including the bone marrow. This report demonstrates that patients with secondary acute myelogenous leukemia may tolerate a double autotransplant procedure and achieve durable remissions.

Acute leukemia occurring after radiotherapy and chemotherapy with a nitrosourea, PCNU

Secondary acute leukemias can occur in patients who have been treated with chemotherapy. Several reports have shown that treatment with nitrosoureas can result in secondary leukemia, but this is the first report implicating the investigational drug PCNU as a cause. This case is unique because of the cytogenetic findings, the short latency period between the chemotherapy and the diagnosis of leukemia, and the successful treatment of the leukemia with high-dose cytarabine (ara-C).

Second primary malignancy after Hodgkin's disease, ovarian cancer and cancer of the testis: a population-based cohort study

The risk of second primary malignancy was assessed in a population-based cohort study of all persons registered with Hodgkin's disease (n = 2,970), ovarian cancer (n = 11,802) and testicular cancer (n = 2,013) in the South Thames Cancer Registry during the period 1961-80, to identify for further study those second malignancies which might be treatment-related. A total of 244 second malignancies was observed. After adjustment for age, sex and calendar period, the relative risk of any second malignancy was 1.4 (90% confidence interval (CI) 1.1-1.7) after Hodgkin's disease, 1.1 (90% CI 1.0-1.2) after ovarian cancer and 0.7 (90% CI 0.5-1.0) after testicular cancer. In particular, the relative risk for leukaemia was 11.9 after Hodgkin's disease, 3.7 after ovarian cancer and 2.5 after testicular cancer. Excess risks were also observed for cancers of the cervix and lung after Hodgkin's disease, for cancers of the breast, lung and rectum after ovarian cancer, and for contralateral testicular cancer. Confounding by social class or smoking does not explain these observations. The excess risks of leukaemia and of second cancer were higher in patients first diagnosed with Hodgkin's disease and ovarian cancer in the 1970s than for those first diagnosed in the 1960s. Increased use of multiple-agent chemotherapy regimes for these tumours in the 1970s may have contributed to these increases in excess risk.

Randomized trial of oral adjuvant razoxane (ICRF 159) in resectable colorectal cancer: five-year follow-up

Razoxane is one of the few agents which has shown activity in the treatment of advanced colorectal cancer. The drug has therefore been evaluated in a prospective randomized controlled trial as an adjuvant to surgery for resectable colorectal cancer. The results to median follow-up of 5 years are reported here. Accrual has ceased and a total of 272 patients entered the trial (133 control, 139 treatment). Treated patients received razoxane postoperatively on a continuous, long-term basis while control patients received identical clinical care but no adjuvant chemotherapy. Analysis of the results shows a significant prolongation of the time to recurrence for Dukes' C patients. All other groups including the overall analysis show no benefit although there is a consistent trend in favour of the treated patients except in Dukes' group 'D'. Razoxane is tolerated well by patients and causes minimal side-effects. However acute leukaemia occurred in three patients (2.45 per cent) after prolonged exposure to the drug and further evaluation should be in patients who are at high risk of developing recurrent cancer, in whom such a risk may be acceptable. It is concluded that razoxane is suitable for further evaluation in colorectal cancer and for incorporation into combination chemotherapy regimens.

Radiation-induced soft-tissue sarcoma

Twenty patients with soft-tissue sarcomas arising within previously irradiated fields have been analysed. The initial radiation dose ranged from 8.8 to 70 Gy, comprising either orthovoltage or megavoltage treatment. The latent interval following radiotherapy ranged from 7 to 45 years (mean 16.8 years). The commonest histological subtype was malignant fibrous histiocytoma. Four patients required forequarter amputation. The 5-year survival was only 14 per cent. The high morbidity and mortality accompanying post-radiation sarcomas must be borne in mind when the choice between therapeutic options for potentially curable cancers is finely balanced.

Bone marrow transplantation for acute monocytic leukemia following the treatment of Hodgkin's disease

A 32-year-old woman developed acute monocytic leukemia within a year of treatment for Hodgkin's disease with chemotherapy and radiation. Residual leukemia was present in the bone marrow after two induction courses of high-dose Ara-C. She received a bone marrow transplant from an HLA- and DR-identical sister and remains in complete remission more than 2 years after transplantation. Only one other instance of a remission greater than 2 years after transplantation for secondary acute leukemia could be found in the literature. Although bone marrow transplantation may be carried out successfully in these patients, it is possible that they may be more vulnerable to transplant-related complications because of their previous exposure to chemotherapy and radiation. Only further study can clarify this matter and determine the best time for the procedure and which regimen should be used.

Myelodysplastic syndromes: pathogenesis, functional abnormalities, and clinical implications

The myelodysplastic syndromes represent a preleukaemic state in which a clonal abnormality of haemopoietic stem cell is characterised by a variety of phenotypic manifestations with varying degrees of ineffective haemopoiesis. This state probably develops as a sequence of events in which the earliest stages may be difficult to detect by conventional pathological techniques. The process is characterised by genetic changes leading to abnormal control of cell proliferation and differentiation. Expansion of an abnormal clone may be related to independence from normal growth factors, insensitivity to normal inhibitory factors, suppression of normal clonal growth, or changes in the immunological or nutritional condition of the host. The haematological picture is of peripheral blood cytopenias: a cellular bone marrow, and functional abnormalities of erythroid, myeloid, and megakaryocytic cells. In most cases marrow cells have an abnormal DNA content, often with disturbances of the cell cycle: an abnormal karyotype is common in premalignant clones. Growth abnormalities of erythroid or granulocyte-macrophage progenitors are common in marrow cultures, and lineage specific surface membrane markers indicate aberrations of differentiation. Progression of the disorder may occur through clonal expansion or through clonal evolution with a greater degree of malignancy. Current attempts to influence abnormal growth and differentiation have had only limited success. Clinical recognition of the syndrome depends on an acute awareness of the signs combined with the identification of clonal and functional abnormalities.