The first research concerning the multiple primary tumors could trace back to 1921, reporting the incidence of 4.7% in 3000 patients diagnosed with malignant tumors [5]. Continued studies were conducted to find out the possible connections and impact [6, 7]. And the results tend to be similar and limited in various cancers [8, 9]. Almost no significant difference was observed when the survival time of patients with multiple tumors was compared to the patients with a single tumor in the past studies [10,11,12].
In recent years, with the great progress of diagnosis and treatment for tumors, the overall survival of cancer patients has been positively changed, which, however, led to the increased number of patients with multiple primary tumors [7, 13]. A similar phenomenon in GBM patients attracted our attention that usually led to a confusing situation for doctors to develop management plans for them or for researchers to recruit them into clinical trials. Meanwhile, there were few studies on GBM patients with multiple primary tumors in the past 5 years. And the fifth WHO guideline for the classification of CNS tumors identified the GBM as the IDH-wild-type, revolutionizing the understanding and clinical practice. It is worth conducting the study under this new situation.
In the beginning, we collect the data of all patients diagnosed with gliomas and other primary tumors, trying to figure out the difference of clinical and pathological characteristics and the prognosis compared to the control group which consisted of patients with gliomas only. From January 2019 to February 2022, 117 glioma patients were diagnosed with multiple primary tumors. However, considering the relatively better prognosis of patients with WHO II and WHO III gliomas, we finally determined to pick the 45 patients who were diagnosed with IDH-wildtype GBM to conduct the analyses.
We chose the GBM patients diagnosed with IDH-wild-type in the past 3 years, trying to reveal the clinical outcome and characteristics of the GBM patients with multiple primary tumors in the current situation to provide some possible guide for clinical practice. It was observed that the patients with multiple tumors usually got older age when they were diagnosed with GBM. And female patients who were frequently diagnosed with tumors of the reproductive system accounted for a large part in the special group based on our data. The distribution of non-CNS tumors was different from the past studies [14]. Since TERT promoter status and MGMT promoter status had been identified as the factors that strongly influence the prognosis of GBM patients, we choose them as the target to conduct the analysis of pathological characteristics [15,16,17]. Patients with multiple tumors tend to get the mutated TERT promoter, which implies that they may get a worse clinical prognosis [18]. And there was no significant difference in the MGMT promoter status between the two groups. For the last part, the postoperative adjuvant therapy was the only factor that affects the prognosis which was consistent with relevant clinical studies [19, 20].
For the analysis of overall survival, there was no significant difference between the two groups, which was consistent with the past studies [11, 14]. And the further analysis of OS between the GBM patients with benign tumors and GBM patients with malignant tumors showed significant difference, which meant that patients with benign tumors tend to have a longer median OS. According to our following-up results, GBM recurrence or progression is the main cause of death for the patients with primary non-CNS tumors. The malignant tumors diagnosed before, we presume, may have made an impact on the patients’ survival status.
For the limitation of our study, the lower number of patients may negatively and largely affect our analysis. And the number is possibly lower than the real due to the negligence in the process of history taking and recording. Meanwhile, limited data on molecular pathology could not support us to do further analysis on the possible connection between the multiple tumors. In addition, based on the history recording, the information about the complicated tumors is limited. Further exploration could not be conducted. How much of a role dose the complicated tumor play in the clinical outcome remains a question to this study.
To sum up, it is unexpected to find out that there was no significant difference in OS between the two groups. Based on our results, patients with malignant tumors before got a poorer survival outcome probably owing to the damage of the previous tumors or the relatively conservative treatment for them that could drive the progression or recurrence of GBM. Further studies including more patients and data on molecular pathology are urgently required to be conducted to better understand the clinical and pathological characteristics of this special group to provide more convincing guidance for clinical practice and trials. What is more, that may be able to discover some innate mechanism of multiple primary tumors and provide a support for the treatment.