With the economic development and lifestyle changes in China, the incidence of NPC has increased year-after-year, especially in Guangdong, which poses a serious threat to population health. Radiotherapy is generally used in patients with NPC, but radiotherapy will damage the normal tissues, thus affecting the QoL of patients with NPC. In this study multiple linear regression analysis was used and the results suggested that factors affecting the overall QoL of NPC patients included family economic status and clinical stage of the disease. The better the family economic status, the higher the QoL of the patients. The QoL of patients with advanced NPC was lower than patients with early-stage NPC. This finding is consistent with the results of Henian et al. [22–24].
The results of this study showed that the life quality score in the specific module domain was higher, followed by the physical and psychological function domains, while the social function domain had the lowest score. Social function reflects the patient's interpersonal communication, social support, and social role. The social function score is the lowest, which may be because the external performance of NPC patients is apparent, which has a significant impact on their social interaction, thus leading to the lowest score. The psychological function domain mainly reflects the psychological status of patients because most of the patients are treated with radiotherapy. During radiation therapy, patients should bear the brunt of disease, and radiation physical discomfort or even pain, which will manifest in the psychological level of anxiety, depression, and other negative affective disturbances, seriously affect the patient’s QoL during radiotherapy, eventually leading to a lower score on the psychological function domain.
Using simple correlation analysis, it was shown that HGB had a strong and positive correlation with the physical function domain, social function domain, specific module domain, and total score of the scale. With an increase in the HGB level, the life quality score of patients increased gradually. HGB is a special protein that transports oxygen in RBCs and is the protein that gives blood a red color. HGB is composed of globin and heme . The clinical significance of the increase and decrease in HBG is similar to the clinical significance of the RBC count, a decrease of which will affect the transport function of oxygen and carbon dioxide in RBCs . Hypoxic cells are present in tumors, hypoxic cells are a major cause of radiotherapy failure , and oxygen is the strongest radiation sensitizer . HGB is the main carrier of oxygen in the body. The concentration of HGB directly affects the oxygen content of human blood and the oxygen supply to the tumor. When the HGB concentration in the blood decreases, the blood oxygen content decreases, leading to the increase tumor tissue hypoxic cells, making the tumor resistant to radiation . Bodily functions reflect the basic physiologic functions of the patient, including appetite, sleep, defecation, physical pain, and fatigue. With an increase in the HGB content, the physiological function of the patients improved gradually, leading to a gradual increase in the domain of physical function score. Specific symptoms in NPC patients include runny nose, nosebleed, dizziness, headache, and dysphagia, which may be improved with an increase in the HGB level, leading to increased motion-specific field QoL scores.
The results of typical correlation analysis showed that the objective indicators that had a significant impact on the QoL of NPC patients included Alb, TB, BUN, Cre, and AST levels, and the WBC and RBC counts. The higher the Alb, TB, and BUN levels, and the WBC count, the lower the physical domain and social domain scores. The higher the AST and Cre levels, the lower the PHD and TOT scores. WBCs are a component of the immune system. The total number of WBCs and cell classification in the blood will change during an inflammatory reaction, thus causing local tissue damage and causing a variety of complications  and reducing the patient's QoL. ALB is produced by the liver and has a half-life of 18 ~ 20 days. ALB reflects the nutritional status and cachexia of patients with cancer. There are different degrees of protein metabolic disorders in patients with malignant neoplasms, the underlying mechanism of which is not clear, but may be related to the plunder and consumption of large amounts of human protein by tumor cells during the growth process, and the poor appetite, dry mouth, and increased body consumption caused by radical radiotherapy [19–20]. When liver function is impaired, the ALT level is elevated, indicating that the patient may be malnourished or spread cancer cells. It is also possible that the immune system becomes hyperactive and the resistance decreases with a series of uncomfortable symptoms, which further aggravate the disease  is produced by the degradation of senescent RBCs in the blood, and can effectively eliminate peroxy radicals at micromolar concentrations, which has a strong antioxidant capacity and can prevent the generation of free radicals and oxidative damage . Bilirubin can reduce kidney damage by inhibiting inflammatory responses and apoptosis. When the level of TB is reduced is reduced in vivo, the antioxidant and anti-apoptotic abilities are weakened, which can further aggravate the inflammatory response in vivo , resulting in a decline in the QoL. Serum Cre and BUN are commonly used indicators for the evaluation of renal function . Cre, as a metabolite of creatine, is excreted through the kidneys and a small amount is excreted from the renal tubules. An increase in these two indicators indicates that kidney function is impaired, thus affecting the patient's QoL.
Canonical redundancy analysis reflects the degree of variation interpretation fir each canonical variable to the whole original variable group. From the above results, it can be seen that the variation degree of the first pair of canonical variables on the scores in all fields of the scale was not high, indicating that the clinical objective indicators could not fully reflect the patient's QoL, and may also be affected by other factors. Therefore, to study the QoL of NPC patients warrants comprehensive consideration of all factors.