Uracil mustard revisited.

BACKGROUND: A patient with diffuse large cell lymphoma who had a complete response lasting 35 years following a 3-day course of uracil mustard stimulated a recall review of patients treated with this oral alkylating agent. METHODS: Records of patients treated with uracil mustard between 1958 and 1970 were reviewed. A current histologic review according to the International Formulation was performed when possible. Total doses of uracil mustard were similar to those of mechlorethamine, although there were variations in the dose schedule. RESULTS: Employing criteria used over 25 years ago to evaluate patients' responses, the overall regression rate for 94 non-Hodgkin lymphoma patients was 69.2% (complete response [CR] 23.4%). Of 62 patients with Hodgkin disease, 69.4% responded (CR 9.7%). For 39 patients with chronic lymphatic leukemia, the combined complete and partial response rate was 74% (CR 7.7%). Thrombocytopenia was the primary toxicity. CONCLUSIONS: Uracil mustard is an unmarketed, inexpensive oral alkylating agent that has been effective in the treatment of patients with lymphoma, chronic lymphatic leukemia, and thrombocythemia. Perhaps it should be reevaluated.

Progression of essential thrombocythemia to blastic crisis via idiopathic myelofibrosis.

We report a 61-year-old man with essential thrombocythemia (ET) whose clinical course was followed for 12 years. The ET evolved into true idiopathic myelofibrosis (IM) 6 years after the initial diagnosis and progressed to myeloid blastic transformation 6 years later. The cytogenetic analysis showed a normal karyotype during the ET phase but subsequent analysis revealed an abnormal karyotype during the IM phase which evolved clonally at blastic crisis with constant involvement of chromosome 13q and chromosome 7. The close monitoring of essential events, using clinical, morphologic, immunologic and cytogenetic parameters, allowed us to carefully identify the transition from one chronic myeloproliferative disease (MPD) to another. This is only the second case reported showing a clinical evolution of this nature. The clinical and biological aspects of the disease are briefly discussed.

Acute leukemia following treatment of polycythemia vera and essential thrombocythemia with uracil mustard.

Transformation to acute leukemia (AL) is known to occur in polycythemia vera (PV) and essential thrombocythemia (ET). Myelosuppressive therapy with agents such as 32P and alkylating agents increase this risk in both disorders. The alkylating agent, uracil mustard (UM), which is an effective agent for controlling thrombocytosis, has not been reported to be leukemogenic. We have treated 29 patients with UM (9 treated continuously and 20 treated intermittently): II with PV, 16 with ET, and 2 with myelofibrosis (MF). Three patients developed AL, two after continuous therapy. These two patients with PV had received the fourth highest and highest total dose of UM, and their duration of treatment was the third and fourth longest among the nine patients treated continuously, respectively. One out of 20 patients treated intermittently with UM developed AL. This patient (3) with ET had received the highest total dose of UM, and her duration of treatment was the longest among the 20 patients treated intermittently.

Essential thrombocythemia and leukemic transformation.

Alkylating agents and 32P have been widely employed in the treatment of patients with essential thrombocythemia (ET). During a four-month period, we observed 3 cases of ET that had transformed into leukemia. Two patients had been treated with uracil mustard: One developed acute myelogenous leukemia 79 months after institution of therapy, and the other patient developed chronic myelomonocytic leukemia 24 months after the start of therapy. The third patient had been treated with busulfan, and ET evolved into myelofibrosis and eventually into acute undifferentiated leukemia with myelofibrosis. The patient who developed acute myelogenous leukemia was asymptomatic at the time of diagnosis of ET but was treated because his platelet count was greater than 1,000,000/mm3. He died 1 month after leukemic transformation, during induction chemotherapy. The other 2 patients presented with symptoms referable to their thrombocythemia. Review of the English literature revealed 12 other definite or probable cases of ET with leukemic transformation, all but 1 having been treated with alkylating agents and/or 32P. We propose that the natural history of ET may be similar to that of polycythemia vera, with evolution into leukemia being an unusual occurrence except in the setting of previous chemotherapy. Therefore, the current practice of treating asymptomatic patients with ET may not be justified, since administration of alkylating agents or 32P may increase the risk of subsequent development of leukemia.

Pulmonary toxicity recurring after a six week course of busulfan therapy and after subsequent therapy with uracil mustard.

A growing number of drugs, including a number of alkylating agents, have been implicated as the cause of pulmonary diseases. A patient with chronic myelogenous leukemia presented with typical cytology, biopsy, and roentgenologic findings of lung toxicity after only six weeks of therapy with busulfan. There was subsequent clearing. A similar roentgenologic change also occurred after administration of uracil mustard. This has not been reported previously.

Acute leukemia after alkylating-agent therapy of ovarian cancer.

To estimate the leukemogenic potential of alkylating agents, we surveyed 70 institutions using these drugs for the frequency of second cancers in patients with advanced ovarian cancer. Thirteen cases of acute nonlymphocytic leukemia occurred among 5455 patients, as compared to 0.62 cases expected (relative risk = 21.0). All 13 had received alkylating agents. Nine also received radiotherapy. The relative risk for patients given chemotherapy was 36.1 and rose to 171.4 for those surviving for two years (rate = 13.75 per 1000 patients per year). To evaluate the role of therapy versus underlying disease, a historical control of 13,309 patients with ovarian cancer in the National Cancer Institute's End Results Program was analyzed. No excess of leukemia was noted in this group, even among 6596 women receiving radiation. The excess of acute nonlymphocytic leukemia, therefore, appears attribute to alkylating agents, although the effect may be enhanced by exposure to radiation, as previously suggested for Hodgkin's disease.