Fluorouracil cardiotoxicity

5-FU-induced cardiac toxicity--an underestimated problem in radiooncology?

BACKGROUND

5-Fluorouracil (5-FU) is an antimetabolite, which is frequently used as chemotherapeutic agent for combined chemoradiotherapy. The purpose of this study was to present the clinical course of three patients who developed severe cardiac toxicity by 5-FU and to give a review of the literature on the cardiotoxic potential of 5-FU.

RESULTS

Cardiotoxicity is a rare, but relevant side effect of fluoropyrimidines. It comprehends a wide spectrum of side effects, from electrocardiogram changes (69% of cardiac events) to myocardial infarction (22%) and cardiogenic shock (1%).In this case series three patients with cardiotoxic events during chemoradiotherapy including 5-FU, the reaction's characteristics and their influence on further therapy are described. Two of the patients could not be treated with 5-FU any more because they had developed a myocardial ischemia, which was most likely caused by fluorouracil. Another patient, who complained about typical angina pectoris during 5-FU-infusion and had a new left anterior hemiblock, was reexposed with prophylactic administration of nitrendipine.

CONCLUSION

Cardiotoxicity caused by 5-FU is an underestimated problem in radiooncology. Especially patients without history of cardiac disease are often treated as out-patients and therefore without cardiac monitoring. Consequently asymptomatic and symptomatic cardiac events may be overlooked. The benefit of prophylactic agents remains unclear, so close cardiac monitoring is the most established method to prevent manifest cardiotoxic events.

Docetaxel-Associated Paroxysmal Atrial Fibrillation in a Patient Receiving Docetaxel Plus Cyclophosphamide (TC) Therapy

Objective:

To report a case of paroxysmal atrial fibrillation in a patient who was receiving a chemotherapy regimen including docetaxel plus cyclophosphamide (TC).

Case Report:

A 67-year-old woman was receiving TC therapy for stage IIB breast cancer. She developed symptomatic paroxysmal atrial fibrillation following chemotherapy administration. The patient presented with tachycardia-palpitations, a shaking sensation inside her body, shortness of breath, and tightness in her chest that did not radiate. Propafenone treatment was replaced with sotalol. Cycle 2 of chemotherapy was administered and symptoms of atrial fibrillation returned. Sotalol was switched to dronedarone monotherapy and the symptoms resolved.

Discussion:

Based on the Naranjo probability scale, chemotherapy was the probable cause of the patient's episodes of paroxysmal atrial fibrillation.

Conclusions:

As single agents, taxanes have minimal cardiac toxicity, although cardiac toxicity may be higher with precipitating factors. Clinicians caring for patients receiving taxane chemotherapy should be aware of the potential for docetaxel-induced paroxysmal atrial fibrillation.

5-Fluorouracil induces apoptosis in rat cardiocytes through intracellular oxidative stress

Background

Cardiotoxicity is a major complication of anticancer drugs, including anthracyclines and 5-fluorouracil(5-FU) and it can have detrimental effects both in patients and workers involved in the preparation of chemotherapy.

Methods

Specifically, we have assessed the effects of increasing concentrations of 5-FU and doxorubicin (DOXO) on proliferation of H9c2 rat cardiocytes and HT-29 human colon adenocarcinoma cells by MTT assay. Cells were treated for 24, 48 and 72 h with different concentrations of the two drugs alone or with 5-FU in combination with 10^-4 M of levofolene (LF).

Results

5-FU induced a time- and dose-dependent growth inhibition in both cell lines. The 50% growth inhibition (IC:50) was reached at 72 h with concentrations of 4 μM and 400 μM on HT-29 and H9c2, respectively. The addition of LF to 5-FU enhanced this effect. On the other hand, the IC:50 of DOXO was reached at 72 h with concentrations of 0.118 μM on H9c2 and of 0.31 μM for HT-29. We have evaluated the cell death mechanism induced by 50% growth inhibitory concentrations of 5-FU or DOXO in cardiocytes and colon cancer cells. We have found that the treatment with 400 μM 5-FU induced apoptosis in 32% of H9c2 cells. This effect was increased by the addition of LF to 5-FU (38% of apoptotic cells). Apoptosis occurred in only about 10% of HT-29 cells treated with either 5-FU or 5-FU and LF in combination. DOXO induced poor effects on apoptosis of both H9c2 and HT-29 cells (5–7% apoptotic cells, respectively). The apoptosis induced by 5-FU and LF in cardiocytes was paralleled by the activation of caspases 3, 9 and 7 and by the intracellular increase of O²⁻ levels.

Conclusions

These results suggest that cardiotoxic mechanism of chemotherapy agents are different and this disclose a new scenario for prevention of this complication.

Clinical and electrocardiography changes in patients treated with capecitabine

BACKGROUND

We aimed to identify the incidence of cardiac events with capecitabine treatment.

METHODS

The study included 52 patients (median age 59 years) with cancer treated at our Medical Oncology Clinic between 2009 and 2010. Cardiac events from capecitabine treatment were classified into 4 groups: cardiac symptoms, physical signs, electrocardiography (ECG) findings, and severe adverse cardiac effects.

RESULTS

The patients received either single-agent capecitabine or a combination chemotherapy including capecitabine. After initiation of capecitabine, 18 patients (34.6%) had new onset cardiovascular symptoms, 6 (11.5%) had new onset physical signs and 17 (32.6%) had new onset ECG findings. New onset ECG findings included prolonged corrected QT interval (n = 10, 19.2%) and prolonged PR interval (n = 3, 5.8%). Severe adverse capecitabine-induced cardiac side effects were observed in 5.8% of the patients, but none of the patients had myocardial infarction or died.

CONCLUSION

Cardiac events are not rare during capecitebine treatment and patients should be followed closely to avoid cardiac morbidity and mortality.

Preoperative evaluation of the oncology patient

This review focuses on the unique perioperative concerns of patients with cancer undergoing surgery. Importantly, not all surgical procedures are intended as cures: some patients who have cancer also undergo surgery for noncancer issues. Also, many of these patients have undergone prior chemotherapy and/or radiation therapy that can introduce perioperative concerns. These previous treatments, unique to patients with cancer, can adversely affect their cardiovascular, pulmonary, gastrointestinal, renal, and endocrine systems. This article also summarizes many important effects of a wide variety of chemotherapy agents in use today.

Cardiotoxicity with 5-fluorouracil and capecitabine: more than just vasospastic angina

In this case series we present a variety of different cardiac toxicities with 5-fluorouracil and its pro-drug capecitabine, including myocardial infarction, cardiomyopathy, sinoatrial and atrioventricular node dysfunction, takotsubo cardiomyopathy and QT prolongation with torsade-de pointes ventricular tachycardia. We stress the fact that while vasospasm is a well-recognized side-effect of this class of chemotherapeutic agent, broader cardiotoxicity is commonly seen and an increased awareness of the range of toxicity is necessary if repeat toxicity is to be avoided.

Anticancer therapy induced cardiotoxicity: review of the literature

Innovative anticancer strategies have contributed to an improved survival of patients suffering from malignancies, and in some cases, have turned cancer into a chronic disease. Therefore, the early and particularly late onsets of adverse cardiovascular effects of systemic anticancer treatments are of increasing interest. Among a rapidly increasing variety of anticancer drugs, the anthracyclines and the monoclonal antibody, trastuzumab, are the agents with a well-known cardiotoxicity. The diagnostic work-up, the cardiotoxic risk of anthracyclines and trastuzumab, and additionally, cardiotoxicity as a risk factor of a multimodal therapeutic approach in breast cancer patients is discussed in this study.

Preoperative evaluation of the oncology patient

This review focuses on the unique perioperative concerns of patients with cancer undergoing surgery. Importantly, not all surgical procedures are intended as cures: some patients who have cancer also undergo surgery for noncancer issues. Also, many of these patients have undergone prior chemotherapy and/or radiation therapy that can introduce perioperative concerns. These previous treatments, unique to patients with cancer, can adversely affect their cardiovascular, pulmonary, gastrointestinal, renal, and endocrine systems. This article also summarizes many important effects of a wide variety of chemotherapy agents in use today.

Preoperative evaluation of the oncology patient

This article focuses on the unique perioperative concerns of patients with cancer undergoing surgery. Importantly, not all surgical procedures are intended as cures; cancer patients also undergo surgery for noncancer issues. Many of these patients have undergone prior chemotherapy or radiation therapy that can introduce perioperative concerns. These prior treatments, unique to cancer patients, can affect their cardiovascular, pulmonary, gastrointestinal, renal, and endocrine systems adversely, and this article summarizes many important effects of various chemotherapy agents in use today.

Cardiovascular complications of cancer therapy: incidence, pathogenesis, diagnosis, and management

Cancer treatment today employs a combination of chemotherapy, radiotherapy, and surgery to prolong life and provide cure. However, many of these treatments can cause cardiovascular complications such as heart failure, myocardial ischemia/infarction, hypertension, thromboembolism, and arrhythmias. In this article we review the incidence of cardiotoxicity caused by commonly used chemotherapeutic agents as well as discuss the pathogenesis, diagnosis, management, and prevention of these cardiovascular side effects. Cardiotoxicity related to anticancer treatment is important to recognize as it may have a significant impact on the overall prognosis and survival of cancer patients, and it is likely to remain a significant challenge for both cardiologists and oncologists in the future due to an increasing aging population of patients with cancer and the introduction of many new cancer therapies.

Fluoropyrimidine-associated cardiotoxicity: revisited

BACKGROUND

The syndrome of 5-fluorouracil (5-FU)-associated cardiotoxicity remains poorly defined.

PATIENTS AND METHODS

We performed a literature review (1969 - 2007) and compiled data derived from 377 evaluable cases out of 448 reported cases.

RESULTS

Patient age ranged from 14 to 86 years. Of the patients 65% were 55 years old and the male:female ratio was 1.5:1. The most commonly treated tumors were gastrointestinal (60%), head and neck (22%) and breast (4%). Of the patients 14% had a history of heart disease whereas cardiac risk factors were found in 37%. Mode of administration included: continuous infusion (72%); bolus (22.5%); intermediate infusion (3%); oral (2%); and intraperitoneal (1 patient). The dosages of 5-FU used were < 750 mg/m(2)/day (36%), 751 - 999 (16%), 1,000 (26%), 1,001 - 1,499 (4%) and 1,500 (16%). Of the patients 54% received 5-FU in combination with other chemotherapeutic agents (cisplatin 44%) whereas 51% received 5-FU alone or with leucovorin. Only 4% patients had undergone previous or concomitant radiation therapy to the mediastinum. Of cardiac incidents that happened 69% were seen during or within 72 h of the first cycle of 5-FU. Angina occurred in 45% of patients whereas myocardial infarction was seen in 22%, arrhythmias in 23, acute pulmonary edema in 5, cardiac arrest and pericarditis in 1.4 and heart failure in 2. Electro-cardiographic evidence of ischemia or ST-T changes were recorded in 69% of patients, but abnormal cardiac enzymes were found in only 12%. The cardiac symptoms were reproducible in 47%, including in one patient subsequently treated with 5-FU p.o. Symptoms were also elicited when the same patients were treated with lower doses or different schedules. Of the patients 68% responded to conservative anti-anginal therapy, although prophylactic coronary vasodilators had limited efficacy. Overall, 8% of patients showing cardiotoxicity on 5-FU administration died. Furthermore, 13% reexposed to 5-FU died.

CONCLUSIONS

Our review suggests that 5-FU cardiotoxicity is an infrequent but real phenomenon that is independent of dose and may be related to a continuous infusion schedule. The presence of cardiac risk factors is not predictive. Patients should be observed closely and 5-FU administration discontinued if cardiac symptoms develop. A rechallenge with 5-FU should be reserved only for those patients in whom there is no reasonable alternative therapy and should be performed in the setting of aggressive prophylaxis and close monitoring.

Third-degree atrioventricular block and unusual superior vena cava abnormality

During the implantation of a definitive pacemaker for complete atrioventricular block via the left subclavian vein, a rare and abnormal origin of the superior vena cava was detected. No such finding has ever been reported, leading us to adopt the contralateral approach.

Risk factors for enlargement of cardiac silhouette on chest radiography after radiotherapy for esophageal cancer

PURPOSE

To evaluate the incidence and risk factors of enlargement of cardiac silhouette on chest radiographs after radiotherapy for esophageal cancer.

MATERIALS AND METHODS

We analyzed 67 patients with esophageal cancer who received external beam radiation therapy with a total dose of >or=50 Gy and were followed for >or=6 months. Sixteen patients received radiation alone, and the remaining 51 received chemoradiotherapy. The difference between the cardiothoracic ratio (CTR) on the pretreatment chest radiograph and that on the posttreatment radiograph with maximum cardiac silhouette for each patient was used for the analysis.

RESULTS

The average maximum increase in CTR for the entire group was 4.5%, which was statistically significant. Only the area of the cardiac silhouette in the initial radiation field was a significant risk factor for enlargement of the cardiac silhouette. Pericardial effusions were observed in all patients who underwent computed tomography with severe enlargement of the cardiac silhouette.

CONCLUSION

The CTR value significantly increased after radiotherapy for esophageal cancer. Radiation-induced pericardial effusion may be the main cause of enlargement of the cardiac silhouette. The irradiated cardiac area was the only significant risk factor for enlargement of the cardiac silhouette; the use of chemotherapy was not.

5-fluorouracil increases the number and complexity of premature complexes in the heart: a prospective study using ambulatory ECG monitoring

The cardiac toxicity of LV5FU2 (de Gramont) regimen which is a widely used chemotherapy regimen in gastrointestinal system cancers is not well defined. We aimed to evaluate the impact of this regimen on cardiac rhythm. Two Holter ECG recordings were obtained in all patients with gastrointestinal system cancers treated with LV5FU2 regimen as first-line chemotherapy (one before and the second during the first 24 h of chemotherapy). Records were reviewed for the heart rate, rhythm, atrial premature complexes (APC), ventricular premature complexes (VPC), grades according to Lown-Wolf grading system and ST segment changes. Holter ECG recordings were evaluated in 27 patients. In the baseline evaluation, neither clinical symptom nor ST segment changes were observed. During the treatment period, chest pain was observed in two patients without any cardiac enzyme and ST segment changes. Moreover, a decrease in mean heart rate, and an increase in the number and complexity of premature complexes secondary to treatment were observed. The mean heart rate, APC per hour and VPC per hour (+/-SD) before vs. during treatment were, respectively, 93.1+/-16.4 vs. 81.6+/-12.7 (p=0.001), 18.9+/-54.0 vs. 45.3+/-53.8 vs. (p=0.049) and 12.7+/-29.6 vs. 38.1+/-42.1 (p=0.002). LV5FU2 regimen leads to a decrease in mean heart rate and a significant increase in APC and VPC which may lead to serious arrhythmias. These effects must be better understood for a safer administration of this useful and widely used drug regimen.

Angina Pectoris und ST-Hebungen nach Chemotherapie mit 5-FU

We report on the case of a 64 year old male who received chemotherapy for a metastatic squamous cell carcinoma of the oropharynx. The chemotherapeutic regimen consisted of 5-fluorouracil (5-FU) and cisplatin. Six hours after completion of the first 24 h continuous infusion of 5-FU, the patient developed severe chest pain accompanied by vegetative symptoms and a pronounced ST-elevation of the precordial leads. Under the suspicion of an acute anterior myocardial infarction an immediate coronary angiogram was performed, demonstrating a total occlusion of the left anterior descending (LAD) coronary artery close to the left main stem. The other coronary arteries appeared smooth. After the intracoronary administration of nitroglycerine, the LAD reopened spontaneously without any residual stenosis, paralleled by complete relief of all symptoms. Therefore, 5-FU induced coronary spasm was diagnosed. After initial therapy with intravenous nitrate followed by oral calcium channel blocker, the patient remained free of symptoms and no rise in cardiac enzymes were noted. The chemotherapeutic regimen was changed to cisplatin plus docetaxel. No new attacks of chest pain occurred and the antivasospastic therapy could be stopped without further events.

Severe ventricular dysrhythmias and silent ischemia during infusion of the antimetabolite 5-fluorouracil and cis-platin

The antimetabolite 5-fluorouracil is frequently used in the therapy of various malignancies. Cardiotoxicity has frequently been described during treatment, but there is no common agreement on the need to perform cardiovascular monitoring of patients during 5-fluorouracil administration. We report the case of a young patient with an head-neck cancer on whom a continuous electrocardiogram recording was performed, documenting serious ventricular dysrhythmias in the presence of myocardial ischemia during 5-fluorouracil and cis-platin infusion.

5-Fluorouracil cardiotoxicity induced by alpha-fluoro-beta-alanine

Cardiotoxicity is a rare complication occurring during 5-fluorouracil (5-FU) treatment for malignancies. We herein report the case of a 70-year-old man with 5-FU-induced cardiotoxicity, in whom a high serum level of alpha-fluoro-beta-alanine (FBAL) was observed. The patient, who had unresectable colon cancer metastases to the liver and lung, was referred to us for chemotherapy from an affiliated hospital; he had no cardiac history. After admission, the patient received a continuous intravenous infusion of 5-FU (1000 mg/day), during which precordial pain with right bundle branch block occurred concomitantly with a high serum FBAL concentration of 1955 ng/ml. Both the precordial pain and the electrocardiographic changes disappeared spontaneously after the discontinuation of 5-FU. As the precordial pain in this patient was considered to have been due to 5-FU-induced cardiotoxicity, the administration of 5-FU was abandoned. Instead, oral administration of S-1 (a derivative of 5-FU), at 200 mg/day twice a week, was instituted, because S-1 has a strong inhibitory effect on dihydropyrimidine dehydrogenase, which catalyzes the degradative of 5-FU into FBAL. The serum FBAL concentration subsequently decreased to 352 ng/ml, the same as the value measured on the first day of S-1 administration. Thereafter, no cardiac symptoms were observed. The patient achieved a partial response 6 months after the initiation of the S-1 treatment. The experience of this case, together with a review of the literature, suggests that FBAL is related to 5-FU-induced cardiotoxicity. S-1 may be administered safely to patients with 5-FU-induced cardiotoxicity.

Cardiac function after chemoradiation for esophageal cancer: comparison of heart dose-volume histogram parameters to multiple gated acquisition scan changes

In this paper we determine if preoperative chemoradiation for locally advanced esophageal cancer leads to changes in cardiac ejection fraction. This is a retrospective review of 20 patients treated at our institution for esophageal cancer between 2000 and 2002. Multiple gated acquisition cardiac scans were obtained before and after platinum-based chemoradiation (50.4 Gy). Dose-volume histograms for heart, left ventricle and left anterior descending artery were analyzed. Outcomes assessed included pre- and postchemoradiation ejection fraction ratio and percentage change in ejection fraction postchemoradiation. A statistically significant difference was found between median prechemoradiation ejection fraction (59%) and postchemoradiation ejection fraction (54%) (P = 0.01), but the magnitude of the difference was not clinically significant. Median percentage volume of heart receiving more than 20, 30 and 40 Gy were 61.5%, 58.5% and 53.5%, respectively. Our data showed a clinically insignificant decline in ejection fraction following chemoradiation for esophageal cancer. We did not observe statistically or clinically significant associations between radiation dose to heart, left ventricle or left anterior descending artery and postchemoradiation ejection fraction.

[Reversible cardiogenic shock under 5-fluorouracil treatment]

5-fluorouracil, an antimetabolite agent, has been widely used since 1957 for treatment of varied types of cancer such as gastro-intestinal, pancreas, breast, lung, head and neck malignancies. Cardiotoxicity of 5-fluorouracil is rare and was first described in 1975. It can induce severe complications and involve vital prognosis in the short-term. These complications are less known by cardiologists than medical oncologists. The following clinical case represents a potentially serious and rare case of completely reversible cardiogenic shock in a patient with a colo-rectal cancer. A better knowledge of these complications could reduce cases of death by an earlier diagnosis, and a better evaluation of patients with high cardiotoxicity risk.

Coronary artery spasm induced by 5-fluorouracil

The frequently used chemotherapeutic drug 5-fluorouracil (5-FU) is known to cause angina pectoris and arrhythmias; myocardial infarction and sudden cardiac death could occur. Potential reasons for these phenomena range from toxic/metabolic disturbances to coronary artery spasms. This report shows angiographically proven spasmophilia of the coronary arteries and contributes to the understanding of angina pectoris occurring during treatment with 5-FU. Thus, verapamil type calcium antagonists as well as nitrates should be administered primarily in patients with coronary artery disease and in all patients who had been symptomatic during 5-FU administration in order to prevent further episodes.

Cardiotoxicity of cytotoxic drugs

Cardiotoxicity is a well-known side effect of several cytotoxic drugs, especially of the anthracyclines and can lead to long term morbidity. The mechanism of anthracycline induced cardiotoxicity seems to involve the formation of free radicals leading to oxidative stress. This may cause apoptosis of cardiac cells or immunologic reactions. However, alternative mechanisms may play a role in anthracycline induced cardiotoxicity. Cardiac protection can be achieved by limitation of the cumulative dose. Furthermore, addition of the antioxidant and iron chelator dexrazoxane to anthracycline therapy has shown to be effective in lowering the incidence of anthracycline induced cardiotoxicity. Other cytotoxic drugs such as 5-fluorouracil, cyclophosphamide and the taxoids are associated with cardiotoxicity as well, although little is known about the possible mechanisms. Recently, it appeared that some novel cytotoxic drugs such as trastuzumab and cyclopentenyl cytosine also show cardiotoxic side effects.

The effect of dihydropyrimidine dehydrogenase deficiency on outcomes with fluorouracil

The use of fluorouracil has been complicated by unpredictable pharmacokinetics, low response rates and seemingly random toxicity. The variable pharmacology is largely due to inherited differences in expression of the metabolising enzyme dihydropyrimidine dehydrogenase (DPD). This converts fluorouracil to inactive metabolites (catabolic pathway) and ultimately dictates the amount of fluorouracil that is available to be metabolised to cytotoxic nucleotides (anabolic pathway). Absolute and partial DPD deficiency affect around 0.1 and 3% of the Caucasian population, respectively. Administration of conventional doses of fluorouracil to these individuals has resulted in profound bone marrow and gastrointestinal toxicity, especially in those with absolute DPD deficiency. Other forms of toxicity such as myocardial ischaemia have been difficult to attribute directly to DPD deficiency. Efforts to improve outcomes with fluorouracil have included monitoring of fluorouracil concentrations and modifying fluorouracil administration techniques (e.g. from bolus injections to protracted intravenous infusions). In general, these moves have met with limited therapeutic advancement. The recognition that DPD deficiency increases toxicity has lead to the suggestion that genotypic or phenotypic assessment of DPD status prior to initiating fluorouracil may help predict outcomes. The gene that encodes for DPD expression is called DPYD. Approximately 1% of Caucasians are heterozygotes for the DPYD*2A mutation which is the variant allele that is most frequently implicated in DPD deficiency. Screening for this mutation may identify around 60% of individuals with absolute DPD deficiency who are at the greatest risk of toxicity. Another approach is to determine DPD activity in peripheral blood mononuclear cells, with low activity suggesting an increased risk of toxicity. Intratumoral DPD activity may also be assessed with high activity suggesting a poorer response to fluorouracil. Recently, drugs that inhibit DPD (e.g. eniluracil) have become available. These remove much of the variability in fluorouracil pharmacokinetics and may make assessment of DPD activity redundant. Despite the considerable inroads that have been made, further study is needed before the best means of optimising fluorouracil treatment is determined.

Irinotecan and raltitrexed: an active combination in advanced colorectal cancer

BACKGROUND

Irinotecan and raltitrexed are active agents in metastatic colorectal cancer. Preclinical findings suggest a remarkable synergistic activity between the two drugs and the feasibility of this association has been shown in a recent phase I study. The aim of our phase II trial was to assess the efficacy and tolerability of the combination of irinotecan and raltitrexed in patients with metastatic colorectal cancer untreated with chemotherapy.

PATIENTS AND METHODS

From June 1998 to February 2000, 46 patients were enrolled. Patients received irinotecan 350 mg/m(2) on day 1 and raltitrexed 2.6 mg/m(2) on day 2, every 3 weeks, for up to nine courses. Tumour assessment was performed every three cycles.

RESULTS

A total of 223 cycles of chemotherapy, with a median number of six (range 1-9) courses per patient, was administered. According to intention-to-treat analysis, the overall response rate was 46% (95% confidence interval 31% to 61%). The median duration of response was 21 weeks (range 11-> or =101), the median time to progression 27 weeks (range 1-> or =116), and the median overall survival 57 weeks (range 1-> or =130). The main toxicities were diarrhoea, with National Cancer Institute common toxicity criteria grade 3/4 in 26% of patients, grade 3/4 neutropenia in 20%, grade 3 nausea-vomiting in 13%, grade 3 asthenia in 11% and grade 3/4 transaminase elevation in 4%.

CONCLUSIONS

Results achieved with irinotecan and raltitrexed show that this regimen is active, despite 'not-negligible' toxicity, and may represent a useful regimen for specific subgroups of colorectal cancer patients.

[Emergency coronary angioplasty following treatment with 5-fluorouracil]

INTRODUCTION

The incidence of cardiac toxicity due to 5-fluorouracil (5-FU) ranges from 1.2 to 18%. Most complications occur at the time of the first cure. Their mechanisms have not yet been clearly defined.

EXEGESIS

The authors report a case of unstable angina induced by 5-FU. A coronary angioplasty was performed on a previously ignored coronary lesion.

CONCLUSION

Recent studies support the hypothesis that 5-FU has endothelial toxicity resulting in thrombogenic effect and release of vasoactive substances. Unstable angina pectoris would be related to plaque rupture caused by 5-FU. Patients with previous history of coronary disease are at significantly increased risk for 5-FU-induced cardiotoxicity. They probably would benefit from continuous electrocardiographic monitoring. Rechallenge with 5-FU after cardiotoxicity problems should include only those patients for whom there is no alternative treatment.

Cardiotoxicity of the antiproliferative compound fluorouracil

The antimetabolite fluorouracil (5-FU) is frequently administered for chemotherapy of various malignant neoplasms. The drug is well known for its adverse effects involving bone marrow, skin, mucous membranes, intestinal tract and central nervous system, whereas its cardiotoxicity is less familiar to clinicians. The pathophysiology of fluorouracil-associated cardiac adverse events is controversial and conclusions are based on clinical studies and case reports more than on solid experimental evidence. While clinical and electrocardiographic features suggest myocardial ischaemia as a main aetiological factor, possibly induced by coronary vasospasm, histomorphological and biochemical studies indicate a more direct drug-mediated cytotoxic action. Estimates of the overall incidence of fluorouracil cardiotoxicity have varied widely from 1.2 to 18% of patients. Patients may present with angina-like chest pain, cardiac arrhythmias or myocardial infarction. There is no unequivocally effective prophylaxis or treatment in this syndrome. Once fluorouracil administration is discontinued symptoms are usually reversible, although fatal events have been described. The overall mortality rate has been estimated to be between 2.2 and 13.3%. There is a high risk of relapse when patients are re-exposed to this drug following previous cardiac incidents. From the present data it is concluded that cardiotoxicity is a relevant but underestimated problem in fluorouracil treatment. Since the mechanisms of fluorouracil-associated cardiotoxicity are not yet fully understood, all patients undergoing this chemotherapy have to be carefully evaluated and monitored for cardiac risk factors and complaints. After cardiotoxic events, fluorouracil should definitely be withdrawn and replaced by an alternative antiproliferative regimen.

Raltitrexed (Tomudex): an alternative drug for patients with colorectal cancer and 5-fluorouracil associated cardiotoxicity

Two patients with proven 5-fluorouracil (5-FU)-associated cardiotoxicity were treated with the specific thymidylate synthase inhibitor raltitrexed safely, without evidence of cardiotoxicity. Raltitrexed might be an alternative for patients with advanced colorectal cancer and 5-FU-associated cardiotoxicity. 5-FU cardiotoxicity is not due to the antineoplastic mechanisms via thymidilate synthase.

The anti-cancer drug 5-fluorouracil is metabolized by the isolated perfused rat liver and in rats into highly toxic fluoroacetate

We report the first demonstration of the biotransformation of the anti-cancer drug 5-fluorouracil (FU) into two new metabolites, alpha-fluoro-beta-hydroxypropionic acid (FHPA) and fluoroacetate (FAC), in the isolated perfused rat liver (IPRL) and in the rat in vivo. IPRL was perfused with solutions of pure FU at two doses, 15 or 45 mg kg(-1) body weight, and rats were injected i.p. with 180 mg of FU kg(-1) body weight. Fluorine-19 NMR analysis of perfusates from IPRL and rat urine showed the presence of the normal metabolites of FU and low amounts of FHPA (0.4% or 0.1% of injected FU in perfusates from IPRL treated with 15 or 45 mg of FU kg(-1) body weight, respectively; 0.08% of the injected FU in rat urine) and FAC (0.1% or 0.03% of injected FU in perfusates from IPRL treated with 15 or 45 mg of FU kg(-1) body weight, respectively; 0.003% of the injected FU in rat urine). IPRL was also perfused with a solution of alpha-fluoro-beta-alanine (FBAL) hydrochloride at 16.6 mg kg(-1) body weight dose equivalent to 15 mg of FU kg(-1) body weight. Low amounts of FHPA (0.2% of injected FBAL) and FAC (0.07%) were detected in perfusates, thus demonstrating that FHPA and FAC arise from FBAL catabolism. As FAC is a well-known cardiotoxic poison, and FHPA is also cardiotoxic at high doses, the cardiotoxicity of FU might stem from at least two sources. The first one, established in previous papers (Lemaire et al, 1992, 1994), is the presence in commercial solutions of FU of degradation products of FU that are metabolized into FHPA and FAC; these are formed over time in the basic medium necessary to dissolve the drug. The second, demonstrated in the present study, is the metabolism of FU itself into the same compounds.

5-Ethynyluracil (GW776): effects on the formation of the toxic catabolites of 5-fluorouracil, fluoroacetate and fluorohydroxypropionic acid in the isolated perfused rat liver model

We studied the effects of 5-ethynyluracil (GW776), a potent inactivator of dihydropyrimidine dehydrogenase, on the metabolism of 5-fluorouracil (5-FU), in particular with respect to formation of the toxic compounds fluoroacetate (FAC) and 2-fluoro-3-hydroxypropionic acid (FHPA), using fluorine-19 nuclear magnetic resonance and the isolated perfused rat liver model. Livers were perfused with 5-FU alone at a dose of 15 mg kg(-1) body weight or with 5-FU + GW776 at doses of 15 mg 5-FU kg(-1) body weight and 0.5 mg GW776 kg(-1) body weight injected 1 h before 5-FU. All 5-FU was metabolized in experiments with 5-FU alone whereas unmetabolized 5-FU represented 94% of the fluorinated compounds measured in experiments with 5-FU + GW776. GW776 modulated both the catabolic and the anabolic pathways of 5-FU, the most striking effect being on the degradative pathway. The amount of 5-FU catabolites decreased by a factor of 27 in the presence of GW776. The modulator led to a decrease in alpha-fluoro-beta-alanine (FBAL) formation by a factor of approximately 110, while fluoride ion formation decreased by a factor of approximately 10. By strongly lowering the metabolism of 5-FU into FBAL, GW776 circumvented the transformation of FBAL into toxic FAC and FHPA. 5-FU anabolites increased by a factor of approximately 7 in the presence of GW776. The level of free fluoronucleotides and 5-fluorouridine-5'-diphosphate sugars was increased up to fivefold. No incorporation of 5-FU into RNA could be measured in experiments with 5-FU alone whereas, although low (0.1% of 5-FU injected dose), it was detectable in experiments with 5-FU + GW776. These results suggest that GW776 may be useful for attenuating the not very common but serious cardiotoxic and/or neurotoxic side-effects of 5-FU that are probably due to FBAL metabolites.

Creatine kinase elevation associated with 5-fluorouracil and levamisole therapy for carcinoma of the colon. A case report

BACKGROUND

There have been no reports of creatine phosphokinase (CK) elevation during levamisole administration. There is only one prior report of CK elevation of noncardiac origin associated with 5-fluorouracil.

METHODS

A 41-year-old man was diagnosed with Stage B2 colon carcinoma and underwent extensive surgical resection. Adjuvant therapy with 5-fluorouracil and levamisole was initiated after surgery. A complete hematologic and chemistry profile was obtained during weekly clinic visits.

RESULTS

The patient's serum CK levels were normal prior to the initiation of chemotherapy but began to rise after 4 weeks of therapy, Isoenzyme analysis revealed that the CK was 100% from skeletal muscle. When the CK level surpassed 1,000 U/L, chemotherapy was discontinued. The CK levels began to decline immediately, falling to normal within 2 months. All attempts to identify a known cause of the enzyme elevation were negative.

CONCLUSIONS

The temporal relationship between chemotherapy administration, enzyme elevation, and the rapid fall in enzyme levels upon discontinuation of treatment argue strongly in favor of chemotherapy as the etiology of CK elevation in the patient.