DLBCL is the most common subtype of spinal lymphoma, thus it is vital to understand the epidemiology, prognosis and survival prediction of DLBCL. In this study, 917 cases with baseline information were included into the survival analysis. Because of the data based on the large population, we were able to get the incidence trend and calculate the APC from 1991 to 2016. The trend of all and spinal DLBCL both were increased significantly from 1991 to 2003, while the amplitude of decrease of all DLBCL was not significant in the last ten years. Thus, it is vital and possible to research the prognostic factors and predict the survival possibility of the individual patient by new nomograms.
Despite of the increased incidence, it is delightful that the OS and DSS of spinal DLBCL significantly improved in 2010 to 2016 when compared to 1991 to 2009, suggesting that with current lifestyle and medical conditions, the survival is optimistic in recent years. Except for improving medical care and finance, reducing the incidence of the tumor by intervening independent prognostic factors was also essential. In our study, except for year of diagnosis, we demonstrated age of diagnosis and chemotherapy were significantly associated with the prognosis for OS and CSS, primary site was significantly associated with the prognosis for CSS.
To our knowledge, age was were vital and risk factors for patient with DLBCL in other primary sites.[10, 11, 14, 16] As expected, younger age had more favorable survival than older age in both univariate and multivariate survival analysis, and the optimal cutoff value was identified as 65 year and 75 year. The K‐M survival analysis demonstrated that older age was associated with worse prognosis for CSS and OS, with patients more than 75 years having significantly worse prognosis than patients with between 66 and 75 years, with patients under 65 years having better prognosis than patients with between 66 and 75 years.
Han et al reported that sacrum was the rarest primary site. This was represented in this population. In addition, this study showed primary site have significant association with prognosis for CSS, with DLBCL occurred in pelvic bones, sacrum and coccyxy having better prognosis. Thus, paying more attention to patients with spinal DLBCL occurred in vertebral column is necessary.
Ann Arbor Stage as commonly staging metric for lymphoma was utilized for DLBCL. In this study, the largest number of patients with recorded staging were those diagnosed stage I, followed by stage IV and II, which was consistent with the previous papers.[14, 23] Race diversity in cancer patients still existed. Black men were diagnosed with more advanced than other races, and might have worse in US. In addition, sex as baseline characteristics often were considered as independent prognostic factors in different bone tumors.[14, 15, 25] Except for above baseline characteristics, it is intuitive and possible that the survival time of patients with first primary larger than patients with secondary primary or more. Thus, these factors must be taken into account in the survival analysis. Surprisingly, race, sex, and Ann Arbor Stage were observed no association with the prognosis of OS/CSS in univariate survival analysis. Of course, these factors were not deserved to be included into multivariate survival analysis.
As we all know, DLBCL as one of hematological malignancies, chemotherapy was an optimal treatment. Han et al reported that the majority of patients should receive chemotherapy except individuals whose survival time was too short to receive treatment. Flouzat-Lachaniette et al demonstrated that chemotherapy for DLBCL could significantly shrink the epidural tumor volume. Furthermore, radiation also might be alternative treatment for patients with DLBCL. Peng et al thought the combination of chemotherapy and radiotherapy could efficiently relieve nerve root and spinal cord compression. Several clinicians suggested that the outcome of combination treatment was better than patients treated with radiation or chemotherapy alone. However, the curative effect of radiation lacked statistical support. Considering DLBCL was malignant and aggressive cancer, Han et al observed that surgical decompression significantly improved recovery from neurological deficit. This view was supported by Wang et al, the study showed the 5-year OS rates of patients treated by surgery plus chemotherapy and those received chemotherapy alone were 80.1% and 49.8% respectively. However, Binn et al found there was no significant difference between surgery combined chemotherapy and chemotherapy alone., and even Peng et al considered that decompression surgery had negative impact on prognosis. In our study, based on a large population, we first pointed out that chemotherapy, not surgery and radiation, was the independent prognostic factor for spinal DLBCL. In another word, chemotherapy have favorable curative effect on patients, but radiation alone or surgery alone was not associated with the treatment outcome.
By multivariate analysis, new nomograms have been generated to predict individual survival possibility for that it could integrate all prognostic-related factors and could comprehensively evaluate the cumulative effects of factors on tumor patients. In addition, the new nomogram not only could compare the individual's survival time with the 5-year survival (60 months), but also revealed the population propensity in different subgroups and the distribution of prognosis, which was different from traditional nomogram. For example, we gave one case to display. Furthermore, the C-index and 95%CI for CSS and OS showed the ideal validation of survival prediction.
Of course, several limitations existed in the present study. Firstly, because of limitation of the SEER database, some basic information was not enrolled, including smoking, body mass index, family history. Secondly, we only could obtain the rough treatment. Detail surgical methods and chemotherapy and radiation protocol were not able be acquired. Thirdly, several selection bias might exist in the retrospective trial because of its inherent flaws.