The Prevalence and Associated Factors of Anemia among Breast Cancer Patients Undergoing Chemotherapy: A prospective study

Abstract

Purpose

The purpose of this study was to ascertain the prevalence and factors associated with anemia (hemoglobin [Hb] 12 g/dL) in breast cancer patients undergoing chemotherapy.

Materials and Methods

We conducted a prospective longitudinal study to collect demographic and clinical data on adult breast cancer patients with or without anemia who were admitted to HKL, UMMC, and NCI. The incidence of anemia was determined by detecting whether or not anemia developed during the course of chemotherapy. Mild, moderate, or severe anemia was defined. A chi-square and logistic regression model were used to assess the effect of demographic and clinical factors on the incidence of anemia and multiple logistic regression analysis was used to evaluate the associations of potential risk factors with the presence of CRA.

Results

The study enrolled a total of 292 breast cancer patients. Anemia occurred at a rate of 41.1% (n = 120). Our findings indicated that clinical factors such as the number of chemotherapy regimens, dose reduction, and type of chemotherapy e.g. docetaxel, as well as demographic covariates such as age and BMI, all contribute to the incidence of anemia in cancer patients.

Conclusions

According to this study, the prevalence of anemia in breast cancer patients is high. Patients' age, BMI, number of chemotherapy regimens, and docetaxel were risk factors; thus, protocols are needed to identify subgroups of breast cancer likely to benefit from novel management strategies.

Introduction

Anemia is common in cancer patients, with incidence rates ranging from 22.7% (1) to 63% (2) and increasing to 89% following chemotherapy (3). Increase incidence of Anemia has been associated with reduce treatment response and quality of life of breast cancer patients (4, 5) as well as raise the financial burden of the disease (6). Specific subgroups of patients are more likely to develop anemia during the course of the disease, according to Seshadri et al (7) in a 6-month follow-up survey of cancer patients. Researchers concluded that 73% of patients receiving a combination of both chemotherapy and radiation had anemia, compared to only 58% of those receiving chemotherapy alone. Additionally, the successfully completed European Cancer Anemia Survey (ECAS), a huge multinational prospective survey, provided data on the incidence, and clinical characteristics (e.g., disease status, tumour type, and treatment status) of anemia in a diverse population of patients (8). Anemia was found to be associated with poor performance status in general; a hemoglobin (Hb) level of 9.7 g/dL was used to initiate anemia treatment.

The prevalence of anemia in cancer patients is well documented. According to Xu, H. et al. (3), patients with anemia who are hospitalized to oncology units frequently report feeling more fatigued and experiencing higher mortality rates, as well as developing more comorbidities than those who are not diagnosed with anemia (5). Thus, knowing the prevalence rates of anemia will aid in determining which groups are most likely to benefit from treatment. Numerous obstacles exist when attempting to describe the prevalence of anemia in cancer patients. To begin, a large sample size must be amassed in order to assess the various types of cancer patients. Second, it is critical to take into account the risk of mortality in a population that is already very sick and suffering from cancer. 

Several factors are associated with the prevalence of anemia in cancer patients. The most common factors include demographic factors (9), biological factors (10), chemotherapy (11), and types of cancer (9). Socio-demographic factors including increasing age (12, 9), race e.g., Hispanics (9) and gender e.g., women, played a significant role in the incidence of anemia in cancer patients. Besides, number of chemotherapy regimens (13, 14), type of chemotherapy (13; 9), chemotherapy dose delay or dose reduction (15), all increased incidence of cancer related anemia (CRA). Moreover, cancer itself (13, 16) and type of cancer (17, 16) are associated significantly with anemia among cancer patients. Furthermore, the impact of cancer (by direct invasion of bone marrow), cancer treatment (surgery, hormonal therapy, radiotherapy, targeted therapy), and the effect of cytokines released by cancer cells, all contributed to increases prevalence of anemia in cancer patients (18).

The purpose of this study was to examine the prevalence of and factors contributing to cancer related anemia in a large sample of breast cancer patients admitted to three oncology centers in Malaysia and to provide a basis for future management.

Methods

After obtaining approval from the Ministry of Research and ethical Center (MREC) and institutional review board, we conducted a prospective longitudinal and observational multicenter study of adult patients (aged 18 years or older) admitted to the oncology departments and oncology daycares of Hospital Kuala Lumpur (HKL), University of Malaya Medical Center (UMMC), and National cancer Institute (NCI) between 1^st July 2019 and 31^st March 2020. All patients were followed up three times starting from cycle II.  Patients with Hb levels of ≤12 g/dL (during all follow-ups) or those diagnosed with breast cancer and undergoing chemotherapy alone were included, while patients receiving other types of treatment, such as radiotherapy, surgery, or hormonal therapy, or those in their first cycle, and those suffering from mental or cognitive disorders and unwilling to participate, were excluded.

Sample Size Determination

The sample size was calculated using the single population proportion formula and the based on the incidence of anemia, which ranged from 10 to 40%, assuming p = 0.5 and n = 384. Since the number of patients during the data collection period is less than 10,000, a correction formula is used. NF = n/1 + n/N = 384/1 + 384/750 = 253 NF = desired sample size, n = calculated sample size, N denotes the total population. After adjusting for a 10% non-response rate, the final sample size was 292.

Sampling techniques 

Data was collected from the three major hospitals. First, Hospital Kuala Lumpur (HKL) is a large government hospital in Malaysia that serves as a tertiary and referral hospital in Kuala Lumpur. It has approximately 11300 employees and 2300 beds. Second, the University of Malay Medical Centre (UMMC) in Kuala Lumpur has approximately 1617 beds and serves as a teaching hospital for the University of Malaya. Third, the National Cancer Institute (NCI) is a government cancer treatment facility in Putrajaya, Selangor. It has approximately 252 beds and was specifically designed to provide specialized facilities for cancer patients.

The oncology units and daycare departments of those patients who met the inclusion criteria were identified using their medical records. A one-year review of adults receiving chemotherapy cancer treatment revealed more than 8,000 cases in the oncology units of the three cancer centers. 

Study Outcomes 

Hb levels were determined in patients’ medical records based on blood analysis, and patients with Hb levels ≤ 12 g/dL (during all follow-ups) were defined as anemic breast cancer patients. Hemoglobin levels ≥ 12 g/dL were considered normal (anemia not present). According to the National Cancer Institute, anemia is classified as mild (10 g/dL ≤ Hb - 12 g/dL), moderate (8 g/dL ≤ Hb - 10 g/dL), or severe (Hb ≤ 8 g/dL) (19). We determined the prevalence of anemia at the third follow-up using the same cutoff points as we did at the first and second follow-ups. Patients whose Hb level increased by more than 12 g/dL at any subsequent follow-ups were classified as non-anemic.

Data Collection 

Demographic data (e.g. age, ethnicity, marital status, BMI) were collected and analyzed at all follow-ups. Marital status was classified as married, single, and divorced. Race was categorized as Malay, Indian, Chinese, and others. Patients were classified according to their BMI as obese (BMI kg/m² ≥ 25) or non-obese (BMI kg/m² < 25).  

Clinical data (e.g. cancer stage, chemotherapy dose delay, dose reduction, type and number of chemotherapy) was collected and analyzed at all follow-ups. Cancer stages were divided into four categories: stage I, stage II, stage III, and stage IV. The number of chemotherapy regimens was divided into two categories: one regimen and more than one regimen. Dose delay is defined as a chemotherapy dose that is delayed for more than 7 days (20), and dose reduction is defined as a dose reduction of at least 10% at any consecutive cycle (21, 22).

Statistical analysis

Data analyzed using SPSS version 23. We used regression analysis to examine the relationship between continuous variables and study outcomes, and chi-square χ² tests to examine the relationship between categorical and ordinal variables. We looked at how factors (e.g. age and race) affected the relationships between independent variables and outcome variables. 

Continuous variables were analyzed using the descriptive statistics (mean, standard deviation (SD)). Univariate analyses were conducted using the chi-square or Fisher exact tests, while parametric analyses were conducted using logistic regression analysis. Three steps were taken in analysing the risk factors for anemia. To begin, we examined the relationship between potential anemia risk factors and observed anemia (anemic / non-anemic) using univariate analysis for categorical data. Second, all variables with a p-value < 0.05 significance level in univariate analysis (chi-square or Fisher exact tests) were entered into a stepwise logistic regression model. Thirdly, we examined only risk factors with a statistically significant p-value. The adjusted odds ratio, 95% confidence intervals (95% CI), and p-value are all included in the results of logistic regression analyses. The level of significance was set at a p-value < 0.05.  

Data extraction: 

During the study period, 576 patients were screened at the three hospitals distributed as following: HKL (n=163), NCI (n=281), and UMMC (n=132).  One hundred and fifteen (n=115) of these patients were excluded due to radiotherapy and hormonal therapy. In addition, 141 participants were dropped from the study due to missing data or because they were at the first chemotherapy cycle. Moreover, 28 patients were excluded from the study because they refused to sign the consent form. Finally, there were a total of 292 patients HKL (n=89), NCI (n=125), UMMC (n=78) who were eligible for inclusion in this study (Figure 1).

Ethics approval

All aspects and protocols of this study were reviewed and approved by the Research Ethics Committee of Universiti Teknologi MARA (UiTM) (REC/392/19), Clinical Research Centre (CRC) of Hospital Kuala Lumpur (HKL) (HCRC.IIR-2019-07-163), Institute Kanser Negara (IKN) (IKN/500-5/1/25 JId 4 (18), University of Malaya Medical Centre (UMMC) , and the Medical Research Ethical Centre (MREC) (NMRR -18-3902-45218). The researcher followed the principles of the Helsinki Declaration and Malaysian Good Clinical Practice Guidelines.

Results

Table 1 displays clinical and demographic data for the 292 patients who participated in this study. As shown, the prevalence of anemia was 41.1% (120/292). Of the total number of patients enrolled in the study, 56.6% (68/120) had mild anemia, 34.2% (41/120) had moderate anemia, and 9.1% (11/120) had severe anemia. The average hemoglobin level was 10.34 g/dL. Further, Table 1 shows that approximately 57.9% (169/292) of the patients were Malay, followed by 24% (70/292) Chinese and 13.4% (39/292) Indians. The average mean of hemoglobin level was 10.34 g/dL. Majority of patients were older than 60 years old (74.2%) and the average mean of age were 52.77 years. The majority of patients (74.2%) were over 60 years old, with an average age of 52.77 years. In terms of marital status, 89.4% (261/292) of the patients were married, 5.8% (17/292) were single, and 4.8% (14/292) were divorced. The majority of the patients, 59.6% (174/292) were obese, while 40.4% (118/292) were not. Moreover, approximately 66.8% (195/292), and 68.5% (200/292) of total participants were working and post-menopausal patients, respectively.

In this study, 42.5% (124/292) of the patients were diagnosed with stage III followed by stage IV 22.3% (65/292) and stage I 7.5% (22/292). Additionally, nearly half of patients prescribed a single chemotherapy regimen 48.3% (141/292), and multiple chemotherapy regimens 51.7% (151/292). Finally, in terms of chemotherapy type, approximately 44.9% (131/292) received 5-fluorouracil, epirubicin and cyclophosphamide (FEC) and 27.1% (79/292) received Docetaxel chemotherapy (Table 1).

Anemia data 

As shown in table 2, the prevalence of anemia was 41.1% (120/292). Of the total number of patients enrolled in the study, 56.6% (68/120) had mild anemia, 34.2% (41/120) had moderate anemia, and 9.1% (11/120) had severe anemia. The average mean of hemoglobin level at baseline was 11.12 g/dL (SD 0.641) and declined after receiving chemotherapy to 10.34 g/dL (SD 0.728). Further, anemia was classified based on MCV and MCHC values as microcytic hypochromic anemia 75% (91/120), normocytic normochromic anemia 17.5% (21/120) and macrocytic polychromic anemia 6.6% (8/120). Moreover, table 2 indicated that majority of patients diagnosed with iron deficiency anemia 75.8% (91 /120), 16.7% (20 /120) Vitamin B 12 and folic acid deficiency and 7.5% (9/120) blood loss. Finally, majority of anemic patients did not receive any type of anemia treatment and only 32.5% (39/120) received anemia management. Out of the 39 patients who received anemia treatment, about 71.8% (28/39) treated with iron therapy, folic acid, vitamin B 12, and multi-vitamins. While 28.2% (11/39) underwent blood transfusion and none of the patients treated with Erythropoietin stimulating agents (ESAs) (Table 2).

Prevalence of anemia among breast cancer patients

The prevalence of anemia among breast cancer patients was 41.1%. About 66.9% (n = 89) of anemic patients aged less than 60 and nearly 57.1% (n = 100) of patients with anemia were obese. Fifty six (60.9%) of anemia prevalence was observed among premenopausal breast cancer patients. Considering the patient's cancer stage, approximately 50% (n = 62) of anemic patients were diagnosed with stage III followed by Stage IV 36.9% (n=24) and stage II 29 (35.8%). With regards to the chemotherapy data, about 17.9% (n=27) of patients receiving more than one chemotherapy regimen were affected with anemia and 47% (n=45) prescribed docetaxel (Table 2).

Factors associated with severity of anemia 

Our data indicated that patients with anemia were older than patients without anemia (65.3 vs 54.7 years) (P < 0.05). In comparison to patients without anemia, a significantly greater proportion of breast cancer patients were admitted to oncology daycare units with anemia (66.9% vs 19.5%), and this association persisted after age adjustment (P < 0.05) (Table 2).

Furthermore, chi-square analysis revealed that obese breast cancer patients had a significantly higher incidence of anemia. In addition, obese patients admitted to oncology departments had a higher proportion of anemia than non-obese patients (57.5 and 42.5% vs 16.9 and 83.1%, respectively) (P < 0.05).  In summary, based on results from logistic regression, obese patients were 12.7 times more likely to develop anemia than non-obese patients (P < 0.05) (Table 3)

In terms of cancer stage, of the 292 patients diagnosed with breast cancer, nearly half (50% [62/292]) of all anemia and non-anemia patients were at stage III. The proportion of anemic patients increased with advanced stage: 36.9% (24/292) for anemic patients and 63.1% (41/292) for non-anemic breast cancer patients Table (2). 

We classified patients into groups based on the number of chemotherapy regimens they received and compared the incidence of anemia by the number of regimens. According to chi-square results, the highest proportions of patients prescribed with one chemotherapy were those who suffered from anemia (66% (93/292) and only 48% (34/292) were not suffering from anemia when compared to non-anemic patients who received more than one chemotherapy regimen (17.9% (27/292) and 82.1% (124/292) Table (2).In comparison to patients without anemia , logistic regression analysis indicated that patients who received combination of chemotherapy were 74 times more likely to develop anemia compared to those who received only one chemotherapy regimen (P < 0.05) ( Table 3).

Our data also showed that patients who prescribed with docetaxel chemotherapy treatment but had anemia were more likely to induce anemia than those who did not have anemia (P < 0.05) (Table 3)

Our findings revealed that anemia incidence was significantly associated with both clinical and demographic covariates. However, as shown in Table 4, we found that the clinical covariates explained more of the variance in the model than the demographic covariates (3 clinical variables and 2 demographic variables). 

Discussion

This study successfully identified clinical and demographic characteristics of breast cancer patients that are associated with anemia prevalence. We found that determinants such as the number of chemotherapy regimens used, dose reduction, and docetaxel were independent clinical prognostic indicators of anemia prevalence. Age and BMI were the independent demographic determinants.

Anemia is a frequent complication in critically ill and cancer patients. It has been linked to a reduction in quality of life as well as a poor prognosis (4). In addition, sadness, frustration, and exhaustion can all contribute to a patient’s feeling that life is pointless because of the lowered quality of life associated with anemia (23). Additional research has revealed an increased risk of mortality and complications such as pulmonary edema as a result of cancer related anemia (24, 25). Thus, identifying risk factors for anemia early may assist doctors in optimizing care for critically ill cancer patients (26).

Our data identified a high prevalence of anemia in patients with breast cancer admitted to the oncology departments and daycare centers of HKL, UMMC, and the NCI. Anemia was prevalent in 42.8% of patients at NCI, 30.5% at HKL, and 26.7% at UMMC. 

Numerous researchers have previously reported a high prevalence of anemia in cancer patients in which their results were identical to the current study. For example, the ECAS (8) found that the incidence of anemia in cancer patients was 39.3% which is slightly lower than our finding. On the other hand, our results were lower than the study conducted by Chaumard N et al., (27) who stated that 64.8% of breast cancer patients developed anemia. This proportion varied between 11 and 88% in more detailed and specific research examining adjuvant therapy (28). We think that the difference is due to the different toxicity grading systems used in these studies: anemia was characterized as any recorded Hg level lower than 11 g/dl (28) or 10 g/dl (27), whereas the current study used a cutoff value of 12 g/dl in accordance with the National Cancer Institute grading system. Additionally, patients with cancer who are also anemic may require a different clinical management strategy for their anemia in order to improve their outcomes. Furthermore, the disparity in prevalence rates may be explained by clinical features of immunocompromised patients, such as bad performance status, acute physiologic changes, and inadequate nutrition due to the severity of illness, all of which can result in cancer-related anemia (8), particularly in those patients who have undergone more aggressive treatment.

Moreover, our findings indicated that obesity increases the risk of anemia in cancer patients. According to chi-square analysis, 57.5% of obese breast cancer patients develop anemia, while only 16.9% of non-obese patients do. Logistic regression analysis confirmed these findings, revealing that obese patients were 12.4 times more likely to develop anemia than non-obese breast cancer patients. Our findings are consistent with those of Aigner E, et al. (29) and Camaschella C (30), who established a statistically significant association between obesity and anemia. The suggested explanation could be that obesity impairs nutritional absorption from the duodenum, resulting in iron deficiency anemia (29). Also, heavy eating stimulates the immune system to release excessive amounts of pro-inflammatory cytokines via iron sequestration and suppresses bone marrow’s ability to produce RBCs (31). The body cannot use stored Fe because of inflammation, which also causes anemia.

We found that breast cancer patients who did not have their chemotherapy dose reduced were 1.4 times less likely to develop anemia than those who did have a detected reduced dose (Table 3). In Table 2, the chi-square analysis revealed a significant relationship between chemotherapy dose reduction and anemia prevalence (P < 0.05). Approximately 25% of the anemic breast cancer patients had their dose reduced (Table 2). This result is slightly lower than those reported in two recent studies, which indicated that 26% (20) and 48.2% (21) of all breast cancer patients with a dose reduction. Aside from that, our finding was greater than one study’s finding who reported that 8% of cancer patients had their dose reduced (32). This discrepancy could be explained by the fact that we defined chemotherapy dose reductions as at least a 10% reduction in dose from the first follow-up (21; 22), whereas Nagel C.I et al.,(32) defined them as dose modification from the first follow-up. Chemotherapy dose reductions occur most frequently during late cycles, particularly with FEC and docetaxel regimens (33). There are several possible explanations for this decrease. First, the doses of docetaxel and FEC may be higher than those required for each regimen’s efficacy, particularly in late cycles, resulting in severe toxicities that allowed the oncologist to decrease the chemotherapy dose.  Second, most chemotherapy-sensitive cancer cells may be killed during the initial cycles, and then the dose may be reduced in late cycles to avoid or minimize any negative impact of the chemotherapy. There may be a decrease in the dosage of chemotherapy as a result of the increased incidence of anemia severity or some adverse effects of chemotherapy, such as neutropenia and neuropathy (33; 20).

The multitude of chemotherapy regimens used was found to be a clinical prognostic factor for anemia. This was expected, given chemotherapy’s well-documented bone marrow depressant and acute cytotoxic properties (34). Chemotherapy was associated significantly with anemia prevalence and the interactions we found point to the two subgroups of patients vulnerable to anemia: the elderly and obese breast cancer patients.

Additionally, our findings revealed a link between the type of chemotherapy used, such as docetaxel, and the prevalence of anemia. According to a logistic regression analysis, patients who received docetaxel developed anemia at a higher rate than those who did not receive docetaxel (Table 3). Correspondingly, similar findings indicated a significant relationship between doceatxel and anaemia (35). Despite the fact that anthracycline and taxane-based chemotherapeutic regimens have become the standard of care for breast cancer treatment, they have been shown to reduce mortality and improve survival rates. Docetaxel, on the other hand, has a number of side effects, including cardiac complications and anemia, which increases the prevalence of anemia in patients receiving these types of regimens (36). Furthermore, the mechanism of action of these regimens may result in bone myelosuppression, which causes bone marrow damage and impairs its ability to produce enough red blood cells, white blood cells, and platelets (37).

Cancer-related anemia (CRA) develops in part as a physiological response of the immune system to the action of many cytokines on various iron-homeostasis and erythrocyte-production pathways, which may result in bone marrow suppression (38). Anemia in hematologic cancer patients may be caused by the direct and indirect hemopoietic effects of uncontrolled leukocytosis and cytokine production (29). This would explain why the incidence of anemia is higher in elderly patients admitted to oncology hospitals in this study. While elderly cancer patients may be given less aggressive treatments than younger patients, more research is needed to better understand the determinants of incident anemia in elderly cancer patients requiring critical care.

There are numerous factors that contribute to the occurrence of anemia in cancer patients. Higher levels of inflammatory markers, interleukin-6 and leptin, hepcidin levels, ferritin levels, EPO levels, and reactive oxygen species (ROS) all contribute to the incidence of anemia in cancer patients (13). Anemia is caused by pro-inflammatory cytokines, which directly inhibit the production of red blood cells from the bone marrow (40, 41). Other factors such as poor nutrition, folate deficiency, lengthy hospitalization, and bleeding history, all contributed to anemia incidence in cancer patients (1; 42; 43).

Our study has limitations due to a lack of information regarding anemia treatment. Erythropoietin-stimulating agents (ESAs), for example, were not administered to all patients and only few patients received blood transfusions. Considering that some patients received anemia treatment, such as iron therapy, we detected a rather high prevalence of anemia in our study sample. We understand that anemia can be caused by a number of factors, including underlying cause, cancer relapse or exacerbation, infection, or renal failure.

Our study recommends all oncologists and health care professionals to follow the protocol of NCCN Clinical Practice Guidelines in Oncology and ESMO guidelines which both recommend to treat cancer related anemia based on the etiological causes and anemia severity. If anemia is severe (Hb < 7-8 g/dL), it should be treated with blood transfusion, if moderate (Hb 8-10 g/dL), it should be treated with ESAs and if mild (Hb 10-12 g/dL), it should be treated with iron therapy or multivitamins. ESAs should be added when necessary particularly if anemia is symptomatic and iv iron therapy is added only to improve the efficacy of ESAs and to reduce the need for red blood cell transfusion (45; 46).

Conclusion

Anemia is a common complication in breast cancer patients. The clinical and demographic factors associated with prevalence of cancer-related anemia (CRA) in breast cancer patients were investigated in this study. The current CRA treatment guidelines should be improved to identify which patient subgroups are most likely to develop anemia. Some research is needed to determine the best way to treat anemia in cancer patients and whether or not it affects the patient's health. Our study contributes to that effort by providing data that can be used to identify groups of patients who are more likely to develop anemia. For these groups, optimal cancer management should include effective anemia treatment.

Declarations

Acknowledgement

The author would like to thank everyone at the respective hospitals for their help and generosity in providing access to medical records at the clinic.

Funding

This study did not receive any fund. 

Conflicts of Interest

The authors have no conflicts of interest to declare.

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Tables

Table 1   : Demographic and clinical data for the 292 patients included in the study

*Fluorouracil, Epirubicin, Cyclophosphamide

Table 2:  Anemia Data Among Breast Cancer Patients Receiving Chemotherapy (n=120)

ªThe mean of Hb level is the average mean for the three follow-ups 

*Classification of Anemia based on MCV and MCHC (23).

Table 3: Association between anemia prevalence and demographic and clinical factors.

^a Chi-Square analysis. P < 0.05 indicated a level of significance.

* Fisher Exact Test . P < 0.05 indicated a level of significance.

Table 4 : Type of relationship between anemia prevalence and demographic and clinical factors 

 ^a Logistic regression analysis. P < 0.05 indicated a level of significance.

a FEC, fluorouracil, epirubicin, cyclophosphamide