Anthracycline-induced cardiotoxicity in patients with early-stage breast cancer: the Canadian Cancer Trials Group (CCTG) MA.21 experience.

PURPOSE: Anthracyclines are frequently used in adjuvant treatment for early-stage breast cancer (ESBC). The purpose of this study was to evaluate cardiotoxic effects in the first five years after treatment with different anthracycline-based regimens. METHODS: CCTG MA.21 (NCT000142) was a phase III trial in ESBC that compared cyclophosphamide (75 mg/m2) orally for 14 days, epirubicin (60 mg/m2) and fluorouracil, IV days one and eight (CEF) for six cycles; dose-dense epirubicin (120 mg/m2) and cyclophosphamide, IV every 2 weeks for six cycles with concurrent G-CSF then paclitaxel every 2 weeks for four cycles (ddEC/T); doxorubicin (60 mg/m2) and cyclophosphamide (600 mg/m2) every 3 weeks for four cycles then four cycles q3 weekly paclitaxel (175 mg/m2) (AC/T). ENDPOINTS: LVEF decline; LV function changes (heart failure), or Grade 3-4 cardiac ischemia/infarction. A competing risk analysis was performed with endpoints of cardiotoxicity or recurrence in first 5 years after completion of chemotherapy. RESULTS: 2104 women were randomized. Compliance with cardiac LVEF assessments was 70% at 5 years in all arms. The 5-year cumulative risks of any cardiac event for CEF, ddECT, and AC/T were 22.3% (95%CI 18.9 to 25.7), 14.2% (95%CI 11.0 to 17.3), and 8.1% (95%CI 5.8 to 10.4), respectively, p < 0.0001. At 5 years, women in the ddEC/T and AC/T group had significantly lower risk of cardiotoxicity than those given CEF (HR 0.599 and 0.371, respectively). Most events were asymptomatic drop in LVEF. CONCLUSIONS: Asymptomatic changes in LVEF accounted for most of the cardiotoxicity. The majority of cardiac events occurred in year one although occurrence of cardiotoxicity over time highlights the need for improved risk stratification to guide cardiac surveillance strategies.

Impact of baseline BMI and weight change in CCTG adjuvant breast cancer trials.

BACKGROUND: We hypothesized that increased baseline BMI and BMI change would negatively impact clinical outcomes with adjuvant breast cancer systemic therapy. METHODS: Data from chemotherapy trials MA.5 and MA.21; endocrine therapy MA.12, MA.14 and MA.27; and trastuzumab HERA/MA.24 were analyzed. The primary objective was to examine the effect of BMI change on breast cancer-free interval (BCFI) landmarked at 5 years; secondary objectives included BMI changes at 1 and 3 years; BMI changes on disease-specific survival (DSS) and overall survival (OS); and effects of baseline BMI. Stratified analyses included trial therapy and composite trial stratification factors. RESULTS: In pre-/peri-/early post-menopausal chemotherapy trials (N = 2793), baseline BMI did not impact any endpoint and increased BMI from baseline did not significantly affect BCFI (P = 0.85) after 5 years although it was associated with worse BCFI (P = 0.03) and DSS (P = 0.07) after 1 year. BMI increase by 3 and 5 years was associated with better DSS (P = 0.01; 0.01) and OS (P = 0.003; 0.05). In pre-menopausal endocrine therapy trial MA.12 (N = 672), patients with higher baseline BMI had worse BCFI (P = 0.02) after 1 year, worse DSS (P = 0.05; 0.004) after 1 and 5 years and worse OS (P = 0.01) after 5 years. Increased BMI did not impact BCFI (P = 0.90) after 5 years, although it was associated with worse BCFI (P = 0.01) after 1 year. In post-menopausal endocrine therapy trials MA.14 and MA.27 (N = 8236), baseline BMI did not significantly impact outcome for any endpoint. BMI change did not impact BCFI or DSS after 1 or 3 years, although a mean increased BMI of 0.3 was associated with better OS (P = 0.02) after 1 year. With the administration of trastuzumab (N = 1395) baseline BMI and BMI change did not significantly impact outcomes. CONCLUSIONS: Higher baseline BMI and BMI increases negatively affected outcomes only in pre-/peri-/early post-menopausal trial patients. Otherwise, BMI increases similar to those expected in healthy women either did not impact outcome or were associated with better outcomes. CLINICAL TRIALS NUMBERS: CAN-NCIC-MA5; National Cancer Institute (NCI)-V90-0027; MA.12-NCT00002542; MA.14-NCT00002864; MA.21-NCT00014222; HERA, NCT00045032;CAN-NCIC-MA24; MA-27-NCT00066573.

The effects of lymph node status on predicting outcome in ER+ /HER2- tamoxifen treated breast cancer patients using gene signatures.

BACKGROUND: Lymph node (LN) status is the most important prognostic variable used to guide ER positive (+) breast cancer treatment. While a positive nodal status is traditionally associated with a poor prognosis, a subset of these patients respond well to treatment and achieve long-term survival. Several gene signatures have been established as a means of predicting outcome of breast cancer patients, but the development and indication for use of these assays varies. Here we compare the capacity of two approved gene signatures and a third novel signature to predict outcome in distinct LN negative (-) and LN+ populations. We also examine biological differences between tumours associated with LN- and LN+ disease. METHODS: Gene expression data from publically available data sets was used to compare the ability of Oncotype DX and Prosigna to predict Distant Metastasis Free Survival (DMFS) using an in silico platform. A novel gene signature (Ellen) was developed by including patients with both LN- and LN+ disease and using Prediction Analysis of Microarrays (PAM) software. Gene Set Enrichment Analysis (GSEA) was used to determine biological pathways associated with patient outcome in both LN- and LN+ tumors. RESULTS: The Oncotype DX gene signature, which only used LN- patients during development, significantly predicted outcome in LN- patients, but not LN+ patients. The Prosigna gene signature, which included both LN- and LN+ patients during development, predicted outcome in both LN- and LN+ patient groups. Ellen was also able to predict outcome in both LN- and LN+ patient groups. GSEA suggested that epigenetic modification may be related to poor outcome in LN- disease, whereas immune response may be related to good outcome in LN+ disease. CONCLUSIONS: We demonstrate the importance of incorporating lymph node status during the development of prognostic gene signatures. Ellen may be a useful tool to predict outcome of patients regardless of lymph node status, or for those with unknown lymph node status. Finally we present candidate biological processes, unique to LN- and LN+ disease, that may indicate risk of relapse.

TLE3 is not a predictive biomarker for taxane sensitivity in the NCIC CTG MA.21 clinical trial.

BACKGROUND: TLE3, a nuclear transcriptional repressor downstream of WNT signalling pathways, has been hypothesised as predictive of benefit from adjuvant taxane. METHODS: MA.21 tissue microarrays were constructed from 1097 out of 2104 (52%) patients. TLE3 staining by immunohistochemistry used validated methodology. Continuous TLE3+ (percentage of cells staining positive) was assessed with both visual and automated scoring. The primary objective was to test the predictive effect of TLE3 on relapse-free survival using the MA.21 EC/T and CEF arms and the previously defined cut-point of 30% of cells staining positive in ⩾1 core/tumour. RESULTS: MA.21 patients had 83.2% TLE3 positive (TLE3+) tumours by visual score and 80.6% TLE3+ by automated image analysis while the previously observed rate of TLE3+ cases was 58.6%. TLE3 expression was significantly associated with ER expression (91.2% of ER-positive tumours were TLE3+; P<0.0001). At median 8-year follow-up, there was no evidence of a predictive effect of TLE3 expression with respect to taxane benefit using the established 30% or exploratory quartile cut-points. CONCLUSIONS: Proportionately more MA.21 patient tumours than expected were TLE3+. The pre-specified TLE3+ cut-point of 30% was not predictive of taxane benefit. TLE3 expression does not represent a viable biomarker for taxane benefit in breast cancer.

(18)F-fluorodeoxyglucose positron-emission tomography-computed tomography to diagnose recurrent cancer.

BACKGROUND: Sometimes the diagnosis of recurrent cancer in patients with a previous malignancy can be challenging. This prospective cohort study assessed the clinical utility of (18)F-fluorodeoxyglucose positron-emission tomography-computed tomography ((18)F-FDG PET-CT) in the diagnosis of clinically suspected recurrence of cancer. METHODS: Patients were eligible if cancer recurrence (non-small-cell lung (NSCL), breast, head and neck, ovarian, oesophageal, Hodgkin's or non-Hodgkin's lymphoma) was suspected clinically, and if conventional imaging was non-diagnostic. Clinicians were asked to indicate their management plan before and after (18)F-FDG PET-CT scanning. The primary outcome was change in planned management after (18)F-FDG PET-CT. RESULTS: Between April 2009 and June 2011, 101 patients (age, median 65 years; 55% female) were enroled from four cancer centres in Ontario, Canada. Distribution by primary tumour type was: NSCL (55%), breast (19%), ovarian (10%), oesophageal (6%), lymphoma (6%), and head and neck (4%). Of the 99 subjects who underwent (18)F-FDG PET-CT, planned management changed after (18)F-FDG PET-CT in 52 subjects (53%, 95% confidence interval (CI), 42-63%); a major change in plan from no treatment to treatment was observed in 38 subjects (38%, 95% CI, 29-49%), and was typically associated with (18)F-FDG PET-CT findings that were positive for recurrent cancer (37 subjects). After 3 months, the stated post-(18)F-FDG PET-CT management plan was actually completed in 88 subjects (89%, 95% CI, 81-94%). CONCLUSION: In patients with suspected cancer recurrence and conventional imaging that is non-diagnostic, (18)F-FDG PET-CT often provides new information that leads to important changes in patient management.

Tumor factors predictive of response to hypofractionated radiotherapy in a randomized trial following breast conserving therapy.

PURPOSE: To determine whether tumor grade, molecular subtype and hypoxia predict response to hypofractionated versus standard radiotherapy (RT) following breast-conserving surgery (BCS) for node-negative breast cancer in a randomized controlled trial (RCT). PATIENTS AND METHODS: Formalin-fixed paraffin-embedded (FFPE) tumor blocks were available on 989 of 1234 patients enrolled in the Hypofractionation Whole Breast Irradiation (HWBI) Trial. A central pathology review and assessment of tumor grade using the Nottingham grading system was carried out. Tumors were classified by molecular subtype as luminal A, luminal B, HER2 enriched, basal-like or unclassified using a six-biomarker panel; ER, PR, HER-2, Ki67, CK5/6 and EGFR. Tumors were also classified as hypoxic based on the expression of HIF1α, CAIX or GLUT-1. The primary end point was local recurrence (LR). RESULTS: Median follow-up was 12 years. In the multivariable Cox model, molecular subtype was the only factor predictive of LR, the 10-year cumulative incidence was 4.5% for luminal A and basal-like, 7.9% for luminal B and 16.9% for HER-2 enriched tumors (P < 0.01). Tumor grade, molecular subtype or hypoxia did not predict response to hypofractionation. CONCLUSIONS: In women enrolled in the HWBI trial following BCS tumor molecular subtype predicted LR. However tumor grade, molecular subtype and hypoxia did not predict response to hypofractionation suggesting that patients with node-negative breast tumors of all grades and molecular subtypes may be safely treated with hypofractionated RT regimens.

Do alternative methods of measuring tumor size, including consideration of multicentric/multifocal disease, enhance prognostic information beyond TNM staging in women with early stage breast cancer: an analysis of the NCIC CTG MA.5 and MA.12 clinical trials.

The AJCC staging criteria consider tumor size to be the largest dimension of largest tumor. Some case series suggest using summation of all tumor dimensions in patients with multicentric/multifocal (MC/MF) disease. We used data from NCIC CTG MA.5 and MA.12 clinical trials to examine alternative methods of assessing tumor size on breast-cancer-free-interval (BCFI). The 710 MA.5 pre-/peri-menopausal node positive and 672 MA.12 pre-menopausal node-negative/-positive patients have 10-year median follow-up. All patients received adjuvant chemotherapy. Tumors were centrally reviewed for grade, hormone receptor, and HER2 status. Continuous pathologic tumor size was: (1) largest dimension of largest tumor (cm); (2) tumor area (cm(2)); (3) volume of tumor (cm(3)); (4) with MC/MF disease, summation of (1)-(3) for up to 3 foci. We examined univariate and multivariate effects of tumor size on BCFI utilizing (un)stratified Cox regression and the Wald test statistic. In univariate analysis, larger tumor dimension was significantly associated with worse BFCI in node positive patients: p < 0.0001 for MA.5; p = 0.01 for MA.12. In MA.5 multivariate analysis, larger summation of largest tumor dimensions was associated with worse BCFI (p = 0.0003), while larger single dimension was associated with worse BCFI (p = 0.02) for MA.12. Presence of MC/MF and other tumor size measurements were not associated (p > 0.05) with BFCI. While physicians could consider the largest diameter of the largest focus of disease or the sum of the largest diameters of all foci in their T-stage determination, it appears that the current method of T-staging offers equivalent determinations of prognosis.

A randomized phase II trial of apixaban for the prevention of thromboembolism in patients with metastatic cancer.

BACKGROUND: Cancer patients receiving chemotherapy are at increased risk for thrombosis. Apixaban, a factor Xa inhibitor, is oral and does not require laboratory monitoring. OBJECTIVES: A pilot study was conducted to evaluate whether apixaban would be well tolerated and acceptable in cancer patients receiving chemotherapy. PATIENTS/METHODS: Subjects receiving either first-line or second-line chemotherapy for advanced or metastatic lung, breast, gastrointestinal, bladder, ovarian or prostate cancers, cancer of unknown origin, myeloma or selected lymphomas were randomized to 5 mg, 10 mg or 20 mg once daily of apixaban or placebo in a double-blind manner for 12 weeks. Use of the study drug began within 4 weeks of the start of chemotherapy. The primary outcome was either major bleeding or clinically relevant non-major (CRNM) bleeding. Secondary outcomes included venous thromboembolism (VTE) and grade III or higher adverse events related to the study drug. Thirty-two patients received 5 mg, 30 patients 10 mg, 33 patients 20 mg, and 30 patients placebo. In these groups, there were 0, 0, 2 and 1 major bleeds, respectively. The corresponding data for CRNM bleeds were 1, 1, 2, and 0. The rate of major bleeding in the 93 apixaban patients was 2.2% (95% confidence interval 0.26-7.5%). There were no fatal bleeds. Three placebo patients had symptomatic VTE. CONCLUSIONS: Apixaban was well tolerated in our study population. These results support further study of apixaban in phase III trials to prevent VTE in cancer patients receiving chemotherapy.

Competing events in patients with malignant disease who are at risk for recurrent venous thromboembolism.

Patients with malignant disease enrolled in trials of thrombotic disorders may experience competing events such as death. The occurrence of a competing event may prevent the thrombotic event from being observed. Standard survival analysis techniques ignore competing risks, resulting in possible bias and distorted inferences. To assess the impact of competing events on the results of a previously reported trial comparing low molecular weight heparin (LMWH) with oral anticoagulant (OAC) therapy for the prevention of recurrent venous thromboembolism (VTE) in patients with advanced cancer, we compare the results from standard survival analysis with those from competing risk techniques which are based on the cumulative incidence function (CIF) and Gray's test. The Kaplan-Meier method overestimates the risk of recurrent VTE (17.2% in the OAC group and 8.7% in the LMWH group). Risk of recurrence using the CIF is 12.0% and 6.0% in the OAC and LMWH groups, respectively. Both the log-rank test (p=0.002) and Gray's test (p=0.006) suggest evidence in favor of LMWH. The overestimation of risk is 30% in each treatment group, resulting in a similar relative treatment effect; using the Cox model the hazard ratio (HR) is 0.48 (95% confidence interval [CI], 0.30 to 0.78) and HR=0.47 (95% CI, 0.29 to 0.74) using the CIF model. Failing to account for competing risks may lead to incorrect interpretations of the probability of recurrent VTE. However, when the distribution of competing risks is similar within each treatment group, standard and competing risk methods yield comparable relative treatment effects.

Topoisomerase II alpha protein and responsiveness of breast cancer to adjuvant chemotherapy with CEF compared to CMF in the NCIC CTG randomized MA.5 adjuvant trial.

Overexpression of topoisomerase II protein (topo 2α) is postulated to be more closely associated with responsiveness to anthracycline-containing chemotherapy than human epidermal growth factor receptor type 2 (HER2) gene amplification or alterations in the topoisomerase II alpha gene (TOP2A). The authors used tissue microarrays from 477 of 710 premenopausal women with node-positive breast cancer randomized to CEF or CMF adjuvant chemotherapy in the NCIC Clinical Trials Group Mammary 5 (MA.5) trial. No significant interaction was found between treatment and continuous topo 2α level in either relapse-free (RFS) or overall survival (OS). In 136 patients (28.5%) whose tumors showed topo 2α overexpression by immunohistochemistry based on a cut-off of 13%, CEF was superior to CMF for RFS (adjusted HR 0.45; 95% CI 0.25-0.82; P = 0.009) and OS (adjusted HR 0.50; 95% CI 0.26-0.96; P = 0.04). When tumors lacked topo 2α overexpression, CEF was not superior for RFS (adjusted HR 0.88; 95% CI 0.64-1.22; P = 0.46) or OS (adjusted HR 0.95; 95% CI 0.66-1.38; P = 0.80). Interaction between topo 2α and treatment was borderline significant for RFS (P = 0.04) and OS (P = 0.05) and not substantially more significant than between TOP2A gene alteration (P (interaction) = 0.09 for RFS and 0.02 for OS) or HER2 overexpression (P (interaction) = 0.002 for RFS and 0.009 for OS). Topo 2α protein overexpression based on the cut-off identified in this study, TOP2A gene alterations and HER2 protein overexpression were each associated with responsiveness to anthracycline-containing chemotherapy. The topo 2α protein analysis was exploratory and will require further validation.

PRODIGE: a randomized placebo-controlled trial of dalteparin low-molecular-weight heparin thromboprophylaxis in patients with newly diagnosed malignant glioma.

BACKGROUND AND OBJECTIVES: Venous thromboembolism (VTE) occurs in 20-30% of patients with malignant glioma per year of survival. We tested the efficacy of long-term dalteparin low-molecular-weight heparin (LMWH) for prevention of VTE in these patients. PATIENTS/METHODS: Adults with newly diagnosed malignant glioma were randomized to receive dalteparin 5000 anti-Xa units or placebo, both subcutaneously once daily for 6 months starting within 4 weeks of surgery. Treatment continued for up to 12 months. The primary outcome was the cumulative risk of VTE over 6 months. The target sample size was 512 patients. Events were adjudicated by a committee unaware of treatment. RESULTS: The trial began in 2002 and closed in May 2006 because of expiration of study medication. Ninety-nine patients were randomized to LMWH and 87 to placebo. Twenty-two patients developed VTE in the first 6 months: nine in the LMWH group and 13 in the placebo group [hazard ratio (HR) = 0.51, 95% confidence interval (CI): 0.19-1.4, P = 0.29]. At 6 months, there were three major bleeds on LMWH and none on placebo; at 12 months, 5 (5.1%) major bleeds on LMWH and 1 (1.2%) on placebo occurred (HR = 4.2, 95% CI: 0.48-36, P = 0.22). All major bleeds were intracranial and occurred while on study medication. The 12-month mortality rates were 47.8% for LMWH and 45.4% for placebo (HR = 1.2, 95% CI: 0.73-2.0, P = 0.48). CONCLUSIONS: Trends suggesting reduced VTE and increased intracranial bleeding were seen in the LMWH thromboprophylaxis group. The role of long-term anticoagulant thromboprophylaxis in patients with brain tumors remains uncertain.

Topoisomerase II alpha and responsiveness of breast cancer to adjuvant chemotherapy.

BACKGROUND: Amplification or deletion of the topoisomerase II alpha (TOP2A) gene in breast cancers has been postulated to be more closely associated with responsiveness to anthracycline-containing chemotherapy than amplification of the human epidermal growth factor receptor type 2 (HER2) gene. METHODS: We studied 438 tumors from 710 premenopausal women with node-positive breast cancer who received cyclophosphamide, epirubicin, and 5-fluorouracil (CEF) or cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) as adjuvant chemotherapy in the randomized National Cancer Institute of Canada Clinical Trials Group Mammary 5 (MA.5) trial. TOP2A alterations and HER2 amplification were quantified by fluorescence in situ hybridization. The association of TOP2A and HER2 status with recurrence-free survival (RFS) and overall survival (OS) in the two treatment groups was analyzed using Kaplan-Meier curves, the log-rank test, and Cox proportional hazard models. All statistical tests were two-sided. RESULTS: In patients whose tumors showed TOP2A alterations (either amplifications or deletions), treatment with CEF was statistically significantly superior to treatment with CMF in terms of RFS (adjusted hazard ratio [HR] = 0.35, 95% confidence interval [CI] = 0.17 to 0.73, P = .005) and OS (adjusted HR = 0.33, 95% CI = 0.15 to 0.75, P = .008). In patients without TOP2A amplification or deletion, the corresponding adjusted hazard ratios for RFS and OS were 0.90 (95% CI = 0.66 to 1.23, P = .49) and 1.09 (95% CI = 0.77 to 1.56, P = .62). Adjusted tests of interaction between treatment and TOP2A status were P = .09 for RFS and P = .02 for OS. Adjusted tests of interaction between treatment and HER2 status were P = .008 for RFS and P = .02 for OS. CONCLUSION: TOP2A gene alterations (amplifications or deletions) are associated with an increase in responsiveness to anthracycline-containing chemotherapy regimens relative to non-anthracycline regimens that is similar to that seen in patients with HER2 amplification.

From Trousseau to targeted therapy: new insights and innovations in thrombosis and cancer.

Venous thromboembolism (VTE) commonly occurs in patients with malignant disease. At the 1997 ISTH meeting, cancer and thrombosis was discussed in a state-of-the-art symposium. Since then, there have been many new developments on this topic. Tumors, through expression of tissue factor can activate coagulation. Furthermore, local peritumor activation of coagulation may have important effects on the biology of cancer. A randomized trial has been conducted which evaluated extensive screening to detect underlying malignancy vs. no screening in patients presenting with idiopathic VTE. No statistically significant difference was detected in cancer-related mortality between the two groups. A trial has evaluated extended prophylaxis in patients undergoing surgery for abdominal malignancy. There was a statistically significant reduction in venographically detected deep vein thrombosis in favor of 4 weeks of treatment. In contrast, there is clearly a need for more information on the use of thromboprophylaxis in medical cancer patients. Low molecular weight heparin (LMWH) has replaced unfractionated heparin as the first line treatment in the majority of patients with acute VTE. Many cancer patients with acute VTE can be treated safely at home with subcutaneous LMWH without admission to hospital. The results of a recent trial demonstrated that long-term low molecular weight heparin administered over a 6-month period substantially reduced the rate of recurrent VTE compared with oral anticoagulant therapy with no increase in bleeding. Finally, the first trial specifically designed to evaluate the anticancer effect of long-term LMWH in cancer patients has been conducted and will no doubt stimulate future research.

Epidemiology of thrombosis in cancer.

We have utilized epidemiological data to address three questions in patients with cancer and venous thromboembolism (VTE): (1) What is the risk for occult cancer in patients with idiopathic versus secondary VTE? (2) What is the risk for thrombosis in patients with cancer (vs. noncancer patients)? (3) What is the risk of recurrent VTE in cancer patients with an initial episode of VTE compared to noncancer patients? The risk for a new cancer diagnosis within 6-12 months of the diagnosis of idiopathic VTE (including pulmonary embolism) is well supported by retrospective analyses of large numbers of unselected patients, population-based retrospective cohort analyses from large registries and prospective studies. The odds ratios for these studies are in the range of 4- to 7-fold increased risk. In surgical patients with known cancer the odds ratio for an episode of postoperative VTE is approximately 2, when compared to a control group of noncancer patients subjected to the same procedures. A similar odds ratio of approximately 2 exists for the relative risk for recurrence of VTE in the first 3 months after an initial episode in cancer patients treated with heparin and warfarin (Coumadin) compared to noncancer patients. Therefore, patients with idiopathic VTE are at increased risk for occult cancer and cancer patients are at increased risk for VTE. Appropriate studies are underway to determine the best strategies for anticoagulant management of these patients.

Treatment of venous thrombosis in the cancer patient.

Venous thromboembolism is a common complication in patients with cancer. The management of deep vein thrombosis and pulmonary embolism can be a considerable challenge in patients with cancer. The cancer itself and associated treatments contribute to an ongoing thrombogenic stimulus, while cancer patients are thought to be at increased risk for anticoagulant-induced bleeding. Initial treatment of acute thromboembolism is with intravenous unfractionated heparin or subcutaneous low molecular weight heparin. Treatment at home with low molecular weight heparin is an attractive option in patients with malignant disease. Long-term treatment of acute venous thromboembolism has traditionally been with oral anticoagulants. However, the inconvenience and narrow therapeutic window of oral anticoagulants make such therapy unattractive and problematic in cancer patients. Low molecular weight heparins are being evaluated as an alternative for long-term therapy because their anticoagulant effects are more predictable and laboratory monitoring is unnecessary. Although many clinical issues remain unresolved in the treatment of cancer patients with venous thromboembolism, the future holds much promise as new antithrombotic agents, including factor Xa antagonists and oral thrombin inhibitors, are being tested in clinical trials.

Hemorrhagic complications of anticoagulant treatment.

Bleeding is the major complication of anticoagulant therapy. The criteria for defining the severity of bleeding varied considerably between studies, accounting in part for the variation in the rates of bleeding reported. Since the last review, there have been several meta-analyses published on the rates of major bleeding in trials of anticoagulants for atrial fibrillation and ischemic heart disease. The major determinants of oral anticoagulant-induced bleeding are the intensity of the anticoagulant effect, underlying patient characteristics, and the length of therapy. There is good evidence that low-intensity oral anticoagulant therapy (targeted INR of 2.5; range, 2.0 to 3.0) is associated with a lower risk of bleeding than therapy targeted at a higher intensity. Lower-intensity regimens (INR < 2.0) are associated with an even smaller increase in major bleeding. In terms of treatment decision making for anticoagulant therapy, bleeding risk cannot be considered alone, ie, the potential decrease in thromboembolism must be balanced against the potential increased bleeding risk. The risk of bleeding associated with IV heparin in patients with acute venous thromboembolism is < 3% in recent trials. There is some evidence to suggest that this bleeding risk increases with the heparin dosage and age (> 70 years). LMW heparin is not associated with increased major bleeding compared with standard heparin in acute venous thromboembolism. Standard heparin and LMW heparin are not associated with an increase in major bleeding in ischemic coronary syndromes, but are associated with an increase in major bleeding in ischemic stroke.