| Background:The incidence and mortality of primary lung cancer ranked first among malignant tumors,and according to data,about 11.6%of new malignant tumors are lung cancer in 2018,worldwide[1].Studies have shown that about 80%of lung cancer patients die from the distant metastatic spread of the tumor,with the most common distant metastases being brain metastases[2].Non-small-cell lung cancer(NSCLC)accounts for 80%to 85%of primary lung cancer and small-cell lung cancer(SCLC)accounts for 15%[3,4,5].More than 30%to 50%of NSCLC patients can develop brain metastases in the course of the disease,and it ranges from 60%to 80%of SCLC patients who survive for more than 2 years[6,7].Once brain metastasis is diagnosed,the survival of patients will be greated challenged,and the prognosis is extremely poor if untreated[8,9].In recent years,the incidence of lung cancer has been increasing,and with the continuous improvement of treatment methods,the long-term survival of lung cancer patients has improved compared with before,and the incidence of brain metastases from lung cancer is also increasing[10].Only a few chemotherapeutic drugs can reach the central nervous system to exert therapeutic effects on intracranial metastases due to the blood-brain barrier and therefore have very limited efficacy against intracranial metastases.Because brain metastases are multiple usually,and many lesions are in the deep brain or adjacent to vital functional areas,surgical treatment is often limited by the high risk of surgery.So,radiation therapy remains the main treatment method for brain metastases[11,12].Radiation therapy can be divided into whole-brain radiation therapy(WBRT)and stereotactic radiosurgery(SRS).Traditional WBRT is the standard treatment for brain metastases,which can effectively reduce the intracranial tumor burden palliatively,eliminate microscopic metastases with intracranial dissemination and control the progression of metastases effectively[13].However,large whole-brain parenchymal irradiation can also cause damage to normal tissues,resulting in diffuse radiation damage and thus cognitive dysfunction,which seriously affects the quality at the later stages of life[14,15],and therefore its role in brain metastases has also been questioned.In recent years,with the development of stereotactic radiosurgery,Gamma knife radiosurgery(GKS)has become one of the main methods for the treatment of brain metastases[16],which has the advantages of high precision,micro invasiveness,few complications,wide indications,and no need for general anesthesia.GKS treatment can kill tumor tissue while maximizes the protection of surrounding normal brain tissue,thus alleviating the adverse consequences caused by whole-brain radiation therapy and improving the quality of survival while providing better local control rates.Moreover,the improvement in survival time of patients has been shown to be consistent with the efficacy of surgery[17,18].With the continuous progress of treatment methods,studies on the efficacy and prognostic factors influencing patients after GKS treatment are constantly updated.In order to further explore the prognosis of GKS treatment in patients with brain metastases from lung cancer and the related factors influencing their survival time,a retrospective study of 210 patients with brain metastases from lung cancer admitted to the Department of Neurosurgery of The Second Hospital of Shandong University and received GKS treatment from May 2016 to December 2021 was conducted,and the influence of different factors on survival rates were analyzed.Objectives:To evaluate the prognosis of gamma knife radiosurgery in the treatment for patients with brain metastases from lung cancer and analyze the factors affecting the survival time.Methods:210 patients with brain metastases from lung cancer who treated by gamma knife radiosurgery in the Department of Neurosurgery of our hospital from May 2016 to December 2021 were selected altogether for a retrospective study.The clinical data of patients were collected,including age,sex,Karnofsky Performance Status(KPS)score before treatment,pathological type,number of metastases,total volume of metastases,lesion site,symptoms of brain metastases,control situation of primary disease,situation of radical surgery of lung cancer,radiotherapy and chemotherapy,situation of early intracranial local treatment and others,classified and listed as influencing factors,and follow up their survival data(survive time,cause of death).Overall survival(OS)was defined as the time interval between the time of receiving gamma knife radiosurgery treatment and the date of death or end of follow-up.The Kaplan-Meier method was used to survival analysis,and calculate the median survival time,the 6-month,1-,and 2-year overall survival rates,as well as to plot the survival curves.Log-rank test was used to test the differences in the survival rates between the subgroups.Cox multivariate regression analyses were employed to assess the independent prognostic factors affecting survival.The predictive ability of the model was evaluated by the concordance index(C-index)(Harrell et al.,1982),and the forest plot of estimated survival risk factors was established.Results:All patients were followed-up.131 patients died(62.38%)at the end of follow-up,and the median overall survival after GKS treatment was 16 months(95%Cr=12 to 20).The overall survival rates at 6-month,1-year,and 2-year were 80.75%,56.44%,and 28.22%,respectively.Combined with univariate analysis and multivariate analyses results,age(χ2=5.27,P=0.0217),sex(χ2=5.30,P=0.0213),KPS score before treatment(χ2=16.37,P=0.0003),pathological type(χ2=23.70,P<0.001),number of metastases(χ2=4.31,P=0.0379),control situation of primary disease(χ2=12.49,P=0.0004),and whether the lesion involved the cerebellum(χ2=4.60,P=0.0320)were associated with the survival prognosis,and were independent significant prognostic factors affecting the survival.According to the RTOG evaluation criteria,there were 6 cases(2.86%)with acute CNS radiotherapy response,all of which improved after treatment.Conclusion:1.Gamma knife radiosurgery in the treatment of brain metastases from lung cancer can prolong OS,improve the survival rate,and with few adverse reactions;2.Age,sex,KPS score before treatment,pathological type,number of metastases,control situation of primary disease and whether the lesion involved the cerebellum were associated with the survival prognosis,and were independent prognostic factors affecting the survival of patients treated with GKS.Older age(≥65 years),female,KPS score≥70 points before treatment,adenocarcinoma,the number of metastase(i)s<4,controlled primary disease and lesions not involving the cerebellum were associated with better survival outcomes. |
