Anemia, defined as hemoglobin below 12g/dl according to criteria of the World Health Organization, is a prevalent finding in cancer patients. In palliative care units, its frequency is approximately 70%, being the most common hematologic manifestation in these patients. 1-2
In the oncological context, anemia has a multifactorial etiology whose main mechanism is the decrease in erythroid production in the bone marrow. The causes of this hypoproliferative anemia in cancer patients are diverse. In cases of anemia caused by inflammation or chronic disease, there is an increase in inflammatory cytokines, especially interleukin-6 (IL-6), which interferes with iron homeostasis with greater hepcidin production and decreased erythropoietin synthesis. Furthermore, direct infiltration of the bone marrow by the neoplasm can occur with decreased production of normal hematopoietic cells, such as erythroid precursors, which is frequently observed in hematological neoplasms and tumors of solid metastatic organs, such as breast, prostate, and renal carcinoma. 3
Other mechanisms occur due to iron deficiency, such as chronic bleeding, which occurs mainly in tumors of the gynecological and gastrointestinal tract, nutritional anemia due to anorexia and decreased food intake, and finally as a consequence of cancer treatment itself, due to myelotoxicity of chemotherapy and radiotherapy.3
The clinical manifestations of anemia include symptoms such as dyspnea, fatigue, drowsiness, and malaise, severely reducing the quality of life of these patients and limiting their daily activities.1
With the progressive aging of the population, we have observed an increase in the prevalence of cancer and chronic diseases. Despite advances in medicine, we still deal with therapeutic limitations and with patients without the means to get proper treatment. In this context, palliative care is based on prevention and relief of suffering in patients who face life-threatening diseases, focusing on the treatment of symptoms and the improvement of life quality. 4-5 Furthermore, it rejects the introduction or maintenance of therapies considered futile, that is, those that are unable to modify the natural course of the disease and do not aim to promote the patient's well-being. 5
Thus, the value of blood transfusion as a supportive treatment in hematological and oncological diseases is well established and is seen as an essential part of treatment. However, its role in relieving symptoms in oncohematological patients in palliative care units still needs to be consolidated.2
For patients with advanced cancer, a conservative transfusion strategy is generally used, restricting transfusion to those who are symptomatic and with hemoglobin levels generally less than or equal to 8g / dl2. However, there are few studies that evaluate the real benefit of transfusion in relieving symptoms such as tiredness, loneliness, and dyspnea, as well as in the general improvement of well-being in patients under palliative care.
These symptoms may be related to anemia, but are multifactorial in cancer patients, making it difficult to assess the impact of red blood cell transfusion on symptom relief and its true benefit.2
However, the deleterious effects associated with blood transfusion are well established. Transfusion reactions can range from mild to serious events. Possible immediate transfusion reactions are: transfusion-associated circulatory overload, acute lung injury, transfusion-associated sepsis, and hemolytic reaction due to ABO incompatibility.7
In the palliative care population, the risk of transfusion-associated circulation overload (TACO) should be considered. TACO is characterized by the appearance of cardiogenic pulmonary edema caused by the infusion of a blood component. Prospective and retrospective hemovigilance analyzes report incidence of TACO in 1% to 6% of transfused patients, with an estimated mortality of up to 10%. The risk factors for the appearance of this transfusion reaction are advanced age, low weight, hypoalbuminemia, impaired renal function, among others, such characteristics that are frequently observed in this group of oncohematological patients.8,9
Thus, the use of blood transfusion in advanced disease may be associated with reduced survival rates, with mortality rates ranging from 13 to 33% in patients with up to 15 days after red blood cell transfusion. However, this most likely reflects the advanced stage of the disease, rather than establishes a cause-and-effect relationship.1
The scientific literature on the risks and benefits of blood transfusion in the palliative care population is limited, leaving unanswered a number of questions regarding transfusion practices in palliative patients.10
In this context, the decision to recommend transfusion in these patients is a complex ethical decision. If, on the one hand, we must establish therapies that alleviate symptoms and provide comfort, valuing the patient's well-being, on the other hand, we must avoid treatments that bring harm or prove futile or disproportionate to the stage of the disease.
We must also consider that blood transfusion is a high-cost therapy and that the pressure to maintain adequate stocks of blood components has been growing. 1,6,7,10
As an aggravating factor, the criteria used to indicate blood transfusion in these patients, the effect of transfusion on symptoms and quality of life, and the frequency of adverse events in this population are not well established.10
In addition, the benefits observed in clinical patients who received a transfusion cannot simply be extrapolated to oncohematological patients in palliative care, due to the disease burden, cachexia, functional status, and side effects of already performed treatments.
Thus, we still do not have definitive evidence of the effect (benefit or harm) of this treatment in palliative care.7,10,11