Intravenous iron versus oral iron versus no iron with or without erythropoiesis- stimulating agents (ESA) for cancer patients with anaemia: a systematic review and network meta-analysis

BACKGROUND

Anaemia is common among cancer patients and they may require red blood cell transfusions. Erythropoiesis-stimulating agents (ESAs) and iron might help in reducing the need for red blood cell transfusions. However, it remains unclear whether the combination of both drugs is preferable compared to using one drug.

OBJECTIVES

To systematically review the effect of intravenous iron, oral iron or no iron in combination with or without ESAs to prevent or alleviate anaemia in cancer patients and to generate treatment rankings using network meta-analyses (NMAs).

SEARCH METHODS

We identified studies by searching bibliographic databases (CENTRAL, MEDLINE, Embase; until June 2021). We also searched various registries, conference proceedings and reference lists of identified trials.

SELECTION CRITERIA

We included randomised controlled trials comparing intravenous, oral or no iron, with or without ESAs for the prevention or alleviation of anaemia resulting from chemotherapy, radiotherapy, combination therapy or the underlying malignancy in cancer patients.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias. Outcomes were on-study mortality, number of patients receiving red blood cell transfusions, number of red blood cell units, haematological response, overall mortality and adverse events. We conducted NMAs and generated treatment rankings. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

Ninety-six trials (25,157 participants) fulfilled our inclusion criteria; 62 trials (24,603 participants) could be considered in the NMA (12 different treatment options). Here we present the comparisons of ESA with or without iron and iron alone versus no treatment. Further results and subgroup analyses are described in the full text. On-study mortality We estimated that 92 of 1000 participants without treatment for anaemia died up to 30 days after the active study period. Evidence from NMA (55 trials; 15,074 participants) suggests that treatment with ESA and intravenous iron (12 of 1000; risk ratio (RR) 0.13, 95% confidence interval (CI) 0.01 to 2.29; low certainty) or oral iron (34 of 1000; RR 0.37, 95% CI 0.01 to 27.38; low certainty) may decrease or increase and ESA alone (103 of 1000; RR 1.12, 95% CI 0.92 to 1.35; moderate certainty) probably slightly increases on-study mortality. Additionally, treatment with intravenous iron alone (271 of 1000; RR 2.95, 95% CI 0.71 to 12.34; low certainty) may increase and oral iron alone (24 of 1000; RR 0.26, 95% CI 0.00 to 19.73; low certainty) may increase or decrease on-study mortality. Haematological response We estimated that 90 of 1000 participants without treatment for anaemia had a haematological response. Evidence from NMA (31 trials; 6985 participants) suggests that treatment with ESA and intravenous iron (604 of 1000; RR 6.71, 95% CI 4.93 to 9.14; moderate certainty), ESA and oral iron (527 of 1000; RR 5.85, 95% CI 4.06 to 8.42; moderate certainty), and ESA alone (467 of 1000; RR 5.19, 95% CI 4.02 to 6.71; moderate certainty) probably increases haematological response. Additionally, treatment with oral iron alone may increase haematological response (153 of 1000; RR 1.70, 95% CI 0.69 to 4.20; low certainty). Red blood cell transfusions We estimated that 360 of 1000 participants without treatment for anaemia needed at least one transfusion. Evidence from NMA (69 trials; 18,684 participants) suggests that treatment with ESA and intravenous iron (158 of 1000; RR 0.44, 95% CI 0.31 to 0.63; moderate certainty), ESA and oral iron (144 of 1000; RR 0.40, 95% CI 0.24 to 0.66; moderate certainty) and ESA alone (212 of 1000; RR 0.59, 95% CI 0.51 to 0.69; moderate certainty) probably decreases the need for transfusions. Additionally, treatment with intravenous iron alone (268 of 1000; RR 0.74, 95% CI 0.43 to 1.28; low certainty) and with oral iron alone (333 of 1000; RR 0.92, 95% CI 0.54 to 1.57; low certainty) may decrease or increase the need for transfusions. Overall mortality We estimated that 347 of 1000 participants without treatment for anaemia died overall. Low-certainty evidence from NMA (71 trials; 21,576 participants) suggests that treatment with ESA and intravenous iron (507 of 1000; RR 1.46, 95% CI 0.87 to 2.43) or oral iron (482 of 1000; RR 1.39, 95% CI 0.60 to 3.22) and intravenous iron alone (521 of 1000; RR 1.50, 95% CI 0.63 to 3.56) or oral iron alone (534 of 1000; RR 1.54, 95% CI 0.66 to 3.56) may decrease or increase overall mortality. Treatment with ESA alone may lead to little or no difference in overall mortality (357 of 1000; RR 1.03, 95% CI 0.97 to 1.10; low certainty). Thromboembolic events We estimated that 36 of 1000 participants without treatment for anaemia developed thromboembolic events. Evidence from NMA (50 trials; 15,408 participants) suggests that treatment with ESA and intravenous iron (66 of 1000; RR 1.82, 95% CI 0.98 to 3.41; moderate certainty) probably slightly increases and with ESA alone (66 of 1000; RR 1.82, 95% CI 1.34 to 2.47; high certainty) slightly increases the number of thromboembolic events. None of the trials reported results on the other comparisons. Thrombocytopenia or haemorrhage We estimated that 76 of 1000 participants without treatment for anaemia developed thrombocytopenia/haemorrhage. Evidence from NMA (13 trials, 2744 participants) suggests that treatment with ESA alone probably leads to little or no difference in thrombocytopenia/haemorrhage (76 of 1000; RR 1.00, 95% CI 0.67 to 1.48; moderate certainty). None of the trials reported results on other comparisons. Hypertension We estimated that 10 of 1000 participants without treatment for anaemia developed hypertension. Evidence from NMA (24 trials; 8383 participants) suggests that treatment with ESA alone probably increases the number of hypertensions (29 of 1000; RR 2.93, 95% CI 1.19 to 7.25; moderate certainty). None of the trials reported results on the other comparisons.

AUTHORS' CONCLUSIONS

When considering ESAs with iron as prevention for anaemia, one has to balance between efficacy and safety. Results suggest that treatment with ESA and iron probably decreases number of blood transfusions, but may increase mortality and the number of thromboembolic events. For most outcomes the different comparisons within the network were not fully connected, so ranking of all treatments together was not possible. More head-to-head comparisons including all evaluated treatment combinations are needed to fill the gaps and prove results of this review.

Erythropoietin or darbepoetin for patients with cancer

BACKGROUND

Anaemia associated with cancer and cancer therapy is an important clinical factor in the treatment of malignant diseases. Therapeutic alternatives are recombinant human erythropoiesis stimulating agents (ESAs) and red blood cell transfusions.

OBJECTIVES

To assess the effects of ESAs to either prevent or treat anaemia in cancer patients.

SEARCH METHODS

This is an update of a Cochrane review first published in 2004. We searched the Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE and other databases. Searches were done for the periods 01/1985 to 12/2001 for the first review, 1/2002 to 04/2005 for the first update and to November 2011 for the current update. We also contacted experts in the field and pharmaceutical companies.

SELECTION CRITERIA

Randomised controlled trials on managing anaemia in cancer patients receiving or not receiving anti-cancer therapy that compared the use of ESAs (plus transfusion if needed).

DATA COLLECTION AND ANALYSIS

Several review authors assessed trial quality and extracted data. One review author assessed quality assessment and extracted data, a second review author checked for correctness.

MAIN RESULTS

This update of the systematic review includes a total of 91 trials with 20,102 participants. Use of ESAs significantly reduced the relative risk of red blood cell transfusions (risk ratio (RR) 0.65; 95% confidence interval (CI) 0.62 to 0.68, 70 trials, N = 16,093). On average, participants in the ESAs group received one unit of blood less than the control group (mean difference (MD) -0.98; 95% CI -1.17 to -0.78, 19 trials, N = 4,715). Haematological response was observed more often in participants receiving ESAs (RR 3.93; 95% CI 3.10 to 3.71, 31 trials, N = 6,413). There was suggestive evidence that ESAs may improve Quality of Life (QoL). There was strong evidence that ESAs increase mortality during active study period (hazard ratio (HR) 1.17; 95% CI 1.06 to 1.29, 70 trials, N = 15,935) and some evidence that ESAs decrease overall survival (HR 1.05; 95% CI 1.00 to 1.11, 78 trials, N = 19,003). The risk ratio for thromboembolic complications was increased in patients receiving ESAs compared to controls (RR 1.52, 95% CI 1.34 to 1.74; 57 trials, N = 15,498). ESAs may also increase the risk for hypertension (fixed-effect model: RR 1.30; 95% CI 1.08 to 1.56; random-effects model: RR 1.12; 95% CI 0.94 to 1.33, 31 trials, N = 7,228) and thrombocytopenia/haemorrhage (RR 1.21; 95% CI 1.04 to 1.42; 21 trials, N = 4,507). There was insufficient evidence to support an effect of ESA on tumour response (fixed-effect RR 1.02; 95% CI 0.98 to 1.06, 15 trials, N = 5,012).

AUTHORS' CONCLUSIONS

ESAs reduce the need for red blood cell transfusions but increase the risk for thromboembolic events and deaths. There is suggestive evidence that ESAs may improve QoL. Whether and how ESAs affects tumour control remains uncertain. The increased risk of death and thromboembolic events should be balanced against the potential benefits of ESA treatment taking into account each patient's clinical circumstances and preferences. More data are needed for the effect of these drugs on quality of life and tumour progression. Further research is needed to clarify cellular and molecular mechanisms and pathways of the effects of ESAs on thrombogenesis and their potential effects on tumour growth.

Erythropoietin or Darbepoetin for patients with cancer--meta-analysis based on individual patient data

BACKGROUND

Erythropoiesis-stimulating agents (ESAs) reduce anemia in cancer patients and may improve quality of life, but there are concerns that ESAs might increase mortality.

OBJECTIVES

Our objectives were to examine the effect of ESAs and identify factors that modify the effects of ESAs on overall survival, progression free survival, thromboembolic and cardiovascular events as well as need for transfusions and other important safety and efficacy outcomes in cancer patients.

SEARCH STRATEGY

We searched the Cochrane Library, Medline, Embase and conference proceedings for eligible trials. Manufacturers of ESAs were contacted to identify additional trials.

SELECTION CRITERIA

We included randomized controlled trials comparing epoetin or darbepoetin plus red blood cell transfusions (as necessary) versus red blood cell transfusions (as necessary) alone, to prevent or treat anemia in adult or pediatric cancer patients with or without concurrent antineoplastic therapy.

DATA COLLECTION AND ANALYSIS

We performed a meta-analysis of randomized controlled trials comparing epoetin alpha, epoetin beta or darbepoetin alpha plus red blood cell transfusions versus transfusion alone, for prophylaxis or therapy of anemia while or after receiving anti-cancer treatment. Patient-level data were obtained and analyzed by independent statisticians at two academic departments, using fixed-effects and random-effects meta-analysis. Analyses were according to the intention-to-treat principle. Primary endpoints were on study mortality and overall survival during the longest available follow-up, regardless of anticancer treatment, and in patients receiving chemotherapy. Tests for interactions were used to identify differences in effects of ESAs on mortality across pre-specified subgroups. The present review reports only the results for the primary endpoint.

MAIN RESULTS

A total of 13933 cancer patients from 53 trials were analyzed, 1530 patients died on-study and 4993 overall. ESAs increased on study mortality (combined hazard ratio [cHR] 1.17; 95% CI 1.06-1.30) and worsened overall survival (cHR 1.06; 95% CI 1.00-1.12), with little heterogeneity between trials (I(2) 0%, p=0.87 and I(2) 7.1%, p=0.33, respectively). Thirty-eight trials enrolled 10441 patients receiving chemotherapy. The cHR for on study mortality was 1.10 (95% CI 0.98-1.24) and 1.04; 95% CI 0.97-1.11) for overall survival. There was little evidence for a difference between trials of patients receiving different cancer treatments (P for interaction=0.42).

AUTHORS' CONCLUSIONS

ESA treatment in cancer patients increased on study mortality and worsened overall survival. For patients undergoing chemotherapy the increase was less pronounced, but an adverse effect could not be excluded.