In this retrospective clinical data study, the survival prognosis of NPC patients was investigated by using the COX regression model, Random-Survival-Forest, and Survival-SVM. Survival-SVM was better than the other two methods. Survival-SVM evolved from SVM upgrade. So, it inherited the advantages of SVM, that is, the model was suitable for data with a small sample size12. This study relied on the SEER database and included a total of 1638 patients. However, in practical plain work, the sample size of a single hospital may be less. So, Survival-SVM had a good unadorned application value. Random survival forests can rank and visualize the importance of variables24, which can elucidate the analysis results more clearly and intuitively. As a semi-parametric model, the accuracy of the COX model was slightly inferior to the other two models. With the advent of the machine learning era, the competitive advantage of traditional Cox may be slowly masked.
The results of this study showed that Sex, Race, Primary Site-labeled, Grade, AJCC Stage Group, AJCC T, AJCC N, AJCC M, Reason no cancer-directed surgery, Radiation recode, Chemotherapy recode, Mets at DX-bone, Mets at DX-brain, Mets at DX-liver, Mets at DX-lung, Surg/Rad Seq, and Marital status at diagnosis were all independent factors affecting the survival prognosis of NPC patients. Age is among the most significant factors affecting NPC. The incidence of NPC was more common after the age of 40 years old25, but incidence also tended to be younger than this age. The older the patient was, the worse the prognosis was; this may be associated with factors, such as body immunity and drug resistance in the elderly26. At present, several studies suggested that NPC pathogenesis may be related to genetics27. So, groups with a family history of inheritance should attach great importance to regular physical examination and undergo assessment regularly. This study found that gender had no significant effect on the survival prognosis of NPC patients. Existing studies showed that NPC is prevalent in yellow people28, and in addition to genetic factors, differences in culture, diet, and lifestyle habits among different ethnic groups may26,29 be responsible for ethnic differences. From the traditional histological grade and tumor stage of clinical malignant tumors, the prognosis of well-differentiated tumors was much better than that of poorly differentiated tumors. From the AJCC stage, the prognosis of patients at the T1N0M0 stage was generally better than that of patients at a later stage. The study further found that patients who underwent tumor resection surgery, as well as patients who underwent systemic therapy, tended to have a better prognosis. NPC, as a special squamous cell carcinoma of the head and neck, is considerably sensitive to both radiotherapy and chemotherapy30, and the results of this study equally prominently showed that both chemotherapy and radiotherapy can improve patient prognosis. The survival prognosis of patients who already developed tumor metastasis was poor, and for such patients, radiotherapy plus chemotherapy treatment modalities can improve survival prognosis. For the marital status of patients, this study found that patients with partners had a better survival prognosis than patients without partners, which may be related to the pacifying care of partners31. We found during the literature survey that no study applied Survival-SVM and survival analysis of NPC patients, and Random-Survival-Forest has not yet been carried out in the field of survival analysis of NPC patients. With the development of random machine learning, NPC as a specific squamous-cell carcinoma, has a relatively higher degree of malignancy compared with other cancers32, and the treatment is based on chemoradiotherapy33. Therefore, the development of an unusual prognostic system for NPC can contribute to more accurate treatment research for NPC patients.
The VIMP of RSF showed that M and Grade were the factors that accounted for a finer weight, and M stage had a much finer impact than T and N compared with traditional clinical stage. It was equally important to find that radiotherapy and chemotherapy were the key factors affecting the survival prognosis of NPC patients and affected whether the patients who underwent systemic therapy were closely related to the survival prognosis of surgery3. The study also demonstrated that the survival prognosis of yellow people, especially Asians, was much lower than that of other races.
This study still had some limitations. In terms of data, the data in this paper were all from the data in the SEER database. Considering that the current data collection work was affected by many factors, the data collection and analysis in China will be introduced in the next article. In addition, due to the sample’s unitedness, the generalization ability of the model may have some limitations Subsequently, we plan to apply the model to other types of data to verify its generalization ability. Limitations are as follows. In terms of data volume, data collection mainly in Europe and America was affected by a variety of factors. Data collection in China will be introduced in the next article. The model came from SEER and mainly contained European and American data. There may be limitations in the generalization ability of the model. The subsequent validation of the generalization ability of the model on other data will be considered.