The findings of the present study indicated the positive effect of the nursing care program supplemented with iron intake on blood parameters and fatigue of the patients undergoing chemotherapy. It was also shown that the hemoglobin of the patients in the intervention group increased after the nursing care program and the severity of their anemia decreased, confirming the effect of training strategies to increase iron absorption and intake. Similarly, Rezaee Seraji et al. showed that the hemoglobin concentration of people who did aerobic exercise increased compared to patients who did not perform the aerobic exercise (
27). However, the authors emphasized aerobic exercise, and the changes in hemoglobin ratio were not very noticeable. In contrast, in the present study and physical activity, the patients received iron and proper nutrition training to increase iron absorption. The results proved the significant impact of the intervention.
One of the essential issues in treating patients with cancer is maintaining blood parameters to be within the normal range or close to it. When the patient refers to chemotherapy, nurses decide to perform or not to perform chemotherapy after reviewing the results of blood cell counts. Thus, the implementation of the treatment program depends entirely on the patient's blood test results. If the blood count decreases, the treatment program will be stopped, affecting the survival of patients. In cancer control and treatment programs, the management of blood parameters, including the maintenance of hemoglobin within the normal range, is of great importance. Accordingly, the studies reviewed above indicated that anemia reduces the prognosis of cancer patients (
29), influences the effectiveness of cancer treatments, and increases the likelihood of tumor cell resistance to treatment, which ultimately reduces the survival of the patient (
30).
Studies have shown that a decrease in the level of erythrocytes and anemia is one of the most common and persistent problems in cancer patients (
31), and its severity depends on the extent of the disease and the severity of treatment. It has been reported that anemia increases the risk of death by 65% in patients with various cancers (
27). Kitano et al. showed that 84% of the patients developed anemia while undergoing chemotherapy and 72% of the patients who had no anemia became anemic during chemotherapy (
32). Bernardo's study also found that 73% of patients developed anemia after starting chemotherapy (
33). The prevalence of anemia was 50% in solid cancers, as reported in Groopman's study and 35% in Seshardi's study (
34,
35). Probably the discrepancies observed in the frequencies reported in various studies are due to the type of study, the studied population, and the definition of anemia. The research sample in the present study included the patients with mild anemia or no symptoms of anemia, and thus the sample was different from those examined in previous studies. The results showed that patients who had attended the nursing care program supplemented with iron intake were less likely to have anemia during the treatment. It was also shown that the patients' hemoglobin level increased by one gram during the intervention, indicating that perhaps one of the factors that can affect the patients' fatigue is the hemoglobin level since the patients reported lower levels of fatigue after the increase in hemoglobin and iron intake in the form of the nursing care program that focused on doing exercise and daily activities, as was confirmed in other studies (
36,
37). However, Cella et al. showed that the patients who had a 2-gram increase in hemoglobin reported less fatigue (
38). These conflicting results can be attributed to the differences in the research population, nursing care program, and other factors. Nevertheless, the results show that improving anemia and hemoglobin levels can affect the severity of fatigue. Other studies also suggested that increasing hemoglobin levels reduces the patient's physical fatigue and improves the patient's physical function (
38). On the other hand, anemia can lead to further problems such as fatigue (
38,
39).
The present study suggested that a significant reduction in the fatigue scores of the patients in the intervention group indicated the effectiveness of the nursing care program. Studies have shown that fatigue is one of the most complex and common problems associated with cancer (
40,
41). Fatigue in cancer patients may be caused by the disease process or related treatments called cancer-induced fatigue (
42). Among the various cancer treatments, chemotherapy is the most common cause of fatigue in patients (
43). Cancer-induced fatigue in many patients is so severe that, if left untreated, it disrupts and limits their daily activities (
44). In the present study, a specific tool was used to measure anemia-related fatigue. This study was also different from other studies in terms of the procedure taken. Therefore, it is possible to discuss anemia-related fatigue with more confidence. As shown, the nursing care program with an emphasis on iron intake can significantly affect anemia-induced fatigue. Limited studies have been performed using this tool, which were primarily descriptive and did not use any intervention. For instance, Ghaffari et al. measured the relationship between the severity of fatigue and anemia and reported a moderate level of anemia-induced fatigue (
24). In Timothy's study, 40% of patients suffered from moderate fatigue (
36). Khozimeh et al. showed that the use of energy-saving strategies significantly reduced the patient's fatigue compared to the control group and the patients in the intervention group better managed their fatigue. Their main energy-saving strategy was to create a balance between the rest and activity times during fatigue induced by the disease (
45). Another study by Abdollahi and Shujaedin suggested that the training protocol improved all aspects of the quality of life and increased physical performance in the intervention group compared to the control group (
46), as was evident in the present study. Despite the effectiveness of exercise in controlling fatigue, studies have shown that the most frequently used strategies by patients were lying down (80.7%) and worshiping (77.9%) and the least frequently used strategies were exercise (5%) and stretching movements (21.4%). Accordingly, it can be argued that the first thing a person does in the face of an unpleasant feeling, such as fatigue, is to stop working and taking a rest. Furthermore, patients wrongly believe that their fatigue increases if they do things such as exercise and walking, and thus they do these activities less frequently (
47). However, according to several studies, doing exercise plays an essential role in reducing the severity of fatigue (
48-
50).
The present study also suggested that the severity of fatigue was lower in the patients in the control group, but it was not significantly different from the fatigue level reported by the participants in the intervention group. One reason is that supplying iron reserves after taking iron supplements, which was effective in reducing fatigue in this group of patients. Besides, the participation of the patients in the control group in the treatment program and the emphasis on iron intake can be other reasons that have led to an increase in hemoglobin levels in the control group.