The Treatment Strategy And Prognostic Factors Of Metastatic Cutaneous Melanoma

BackgroundCutaneous Melanoma(CM)is an aggressive skin cancer with poor prognosis.In spite of that the targeted therapy and immunotherapy have improved the survival of most CM patients,the prognosis and the therapeutic strategy of advanced or metastatic CM is still far from ideal.In current guidelines of metastatic CM,the necessity and value of primary tumor surgery is not mentioned,which might make the newly diagnosed metastatic CM patients confused about whether they should accept this surgery.To complete the existing strategy that mainly including systemic treatment and metastatic surgery/radiotherapy,the role of primary tumor surgery is urgent to be cleared.Besides,the previous studies focusing on the prognostic factors of metastatic CM were mostly with small sample sizes and different conclusions.And the common used method to evaluate prognosis,the TNM staging system,also needs to be further validated and improved on its accuracy and applicability.ObjectiveThe purpose of this study was to analyze the effect of primary tumor surgery on the prognosis of newly diagnosed metastatic CM patients,and to analyze the prognostic factors,as well as to try to improve the existing prognostic assessment methods.MethodThis study collected the case information of patients who were newly diagnosed with metastatic CM during year 2004 to 2015,from the Surveillance,Epidemiology,and End Results(SEER)database.The effect of primary tumor surgery on survival was assessed by using propensity score matching method.Univariate and multivariate COX regression analyses were used to identify the prognostic factors.And the information of distant metastatic organs was collected and analyzed to verify and improve the existing prognostic assessment methods.Results1.Compared with the patients in non-surgery group,people in primary tumor surgery group had a significant better prognosis with a p value less than 0.001.Their median overall survivals(OS)were 13.0 and 6.0 months,and the median CM specific survivals(CMSS)were 15.0 and 7.0 months,respectively.Importantly,after the propensity score matching analysis which had adjusted the imbalance on the baselines of two groups,the prognostic advantage of the surgical group was still significant.2.The multivariable COX regression analysis showed that the protective factors of the prognosis include later diagnostic time(the targeted therapy/immunotherapy period),marriage,primary tumor surgery and metastatic tumor surgery.And the risk factors include older age,male,primary tumor located on the trunk(compared with arms or legs),nodular melanoma(compared with superficial disseminated melanoma)and higher TNM staging.3.The patients were layered according to M stage in the eighth edition of TNM staging,their general difference on survival was significant(P<0.001),but in the paired comparison,the survivals of M1c and M1d were not significantly different(P>0.05).Then,based on the types and numbers of distant metastatic organs,this study divided the patients into four groups,which including the patients only with distant lymph nodes/skin/subcutaneous tissue metastasis,the patients with single visceral organ metastasis(subdivided into lung/bone and brain/liver)and the patients with two or more visceral organs.There were statistically significant differences between the survivals of these four groups,both in the general comparison and paired comparison(P<0.001).Conclusion1.The prognosis of patients accepting primary tumor surgery showed a significant advantage over that of non-surgery patients.2.The protective factors of prognosis included the diagnosis at the targeted therapy/immunotherapy period,marriage,primary tumor surgery and metastatic surgery.And the risk factors included older age,male,primary tumor from the trunk,nodular histological type and higher TNM stage.3.Overcoming certain deficiencies of the existing M stages,the prognostic model involving the types and numbers of metastatic visceral organs showed a relatively better assessing effect.SignificanceFor the first time,basing on a large sample of cases,this study focused on the effect of primary tumor surgery on the survival of newly diagnosed metastatic CM patients and studied the prognosis factors and models.Its results and conclusions might help to improve the existing treatment guidelines and prognosis assessment methods.