To date, nomograms have been established for some cancers compared with traditional prediction tools. They are more accurate in predicting OS [13–15]. ROC, AUC, and DCA showed that our nomogram had good discrimination ability, accurate prediction ability, and instructional significance.
There are five highlights in our study. First, our nomogram is the first to find that marital status is an independent risk predictive factor for OS in bone-metastatic PCa. The outcomes for patients who were USDW were worse than those of married patients, which is similar to the findings of Udumyan et al.  and Libby Ellis et al. . Married people have a higher quality of material and spiritual life due to the care and support of their spouses, which is in accordance with the bio-psycho-social medical model . Second, our study was the first to include chemotherapy treatment variables. For example, taxane-based chemotherapy, which can improve the OS of castration-resistant PCa, has started in the last few years . Third, the present study is the only one to use DCA for the OS of bone-metastatic PCa. Our nomogram offers greater net clinical benefits than the TNM system, indicating that the nomogram is better than the TNM system for predicting the OS of bone-metastatic PCa. Fourth, we converted continuous variables into categorical variables. Fifth, we developed a web calculator for our nomogram that can quickly obtain accurate survival results when patients enter their clinical characteristics.
In 2015, Miyoshi et al. published a nomogram for Japanese patients with bone metastatic PCa . Unlike our results, the contribution of PSA to OS in their study suggested that lower PSA indicated worse outcome and GS did not have the greatest effect on OS, which might have been caused by racial diversity. In Hou et al.’s model, GS had the most significant impact on prognosis, similar to our study . They found that liver metastasis significantly contributed to predicted OS. Bosaily et al. found that GS predicted OS in metastatic PCa , and GS ≥ 8 significantly increased mortality [1, 21].
Moreover, the outcomes of our study confirmed that black, white, and American Indian or Alaska Native (AIAN) patients with bone-metastatic PCa had several-times higher mortality risk than API patients, which was similar to the findings of Hou et al. According to Petrovics et al., the genetic spectra of Caucasian and African-American patients with PCa are different . It is worth mentioning that our nomogram can be used in Western and Asian patients.
The limitations of this study are as follows. First, the number of bone lesions was not analyzed because no information was available in the SEER. Second, our study was a retrospective study, and there may be data bias because patients with missing information were excluded. Third, although we innovatively included chemotherapy and surgical treatment in our nomogram, we did not categorize the treatment and provided a specific plan. Finally, our study lacked data on hemoglobin and alkaline phosphatase levels, which were found to be predictors of bone-metastatic PCa. Despite these limitations, our model was well-calibrated and showed superior discrimination and universal applicability.
In conclusion, our nomogram can guide clinicians to accurately predict the 1-year, 3-year and 5-year OS for patients with bone metastatic PCa, which will be valuable for patients' consultations, clinical evaluations, and choices regarding therapeutic schedules.