Abstract
Background
To identify tumor size could be taken as a decision-making factor in the management of preoperative radiotherapy (RT) for patients with locally advanced rectal cancer (LARC).
Methods
In this study, patients diagnosed with rectal adenocarcinoma and staged at II/III from the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2014 were included. Kaplan-Meier curve was conducted to investigate the overall survival (OS) between subgroups with different tumor sizes and the relationship between the tumor size and the efficacy of preoperative RT.
Results
There were 1402 patients eligible for this study, of whom 1105 (78.8%) received preoperative radiotherapy (RT + S group) and 297 (21.2%) underwent surgery alone (S group). The median OS was comparable between groups of RT + S and S before and after propensity score matching (both P > 0.05), but tumor size was a robust independent risk factor of OS (P < 0.05). 5 cm was then identified to the optimal cut-off value of tumor size using the minimum P value. Further analysis showed that preoperative RT could only benefit those with tumor size > 5 cm (P < 0.05); while on the contrary, it would hamper the OS of those with tumor size ≤ 5 cm and no OS risk factors (P > 0.05).
Conclusion
Data from this retrospective analysis of patients with LARC seems to indicate that tumor size might play a role in the decision-making process for (tumors > 5 cm) or against (tumors ≤ 5 cm) preoperative radiotherapy.
Supplementary Information
The online version contains supplementary material available at 10.1007/s12672-025-03134-6.
Keywords: Locally advanced rectal cancer, Preoperative radiotherapy, Tumor size
Introduction
Preoperative radiotherapy (RT), whether in the form of long-course chemoradiotherapy (LCRT) or short-course radiotherapy (SCRT), is the preferred neoadjuvant treatment strategy for locally advanced rectal cancer (LARC) [1]. However, the long-term survival advantages of this approach have not been unequivocally established [2–4]. Recent studies, such as RAPIDO [5], PRODIGE23 [6], and “Watch-Wait“ [7], have emphasized the importance of “intensified” neoadjuvant strategies, including intensified RT. Furthermore, Lin et al. [8] have reported a promising synergistic effect whether in the form of long-course chemoradiotherapy (LCRT) or short-course radiotherapy (SCRT), is the preferred neoadjuvant treatment strategy for locally advanced rectal cancer between RT and immunotherapy. Nonetheless, worries on RT-related toxicity have decreased but still remain despite the advance of RT technique [9–11]. Hence, there is a need to screen a biomarker that can identify individuals who would derive the greatest benefit from preoperative RT and those who may not require it.
Tumor size serves as an informative characteristic that reflects the tumor burden to a certain extent [12]. In various solid cancers, including liver, breast, and lung cancers, tumor size plays a pivotal role in T staging [13–15]. However, in colorectal cancer (CRC), the significance of tumor size has been largely underestimated. Previous studies have demonstrated that CRC with a larger tumor size is associated with elevated levels of carcinoembryonic antigen (CEA), advanced stages, and unfavorable prognosis [16–18]. Conversely, aggressive characteristics have also been observed in early-stage CRC with small tumor sizes [19, 20]. Undoubtedly, tumor size is a crucial prognostic factor, yet its precise role in the prognosis and management of CRC remains inadequately explored, warranting further investigation.
In this study, we hypothesized that the administration of preoperative RT may not provide overall survival benefits for all LARC patients, and then investigated whether tumor size could serve as an accessible biomarker to aid in the decision-making process regarding preoperative RT.
Methods
Patient selection
Data on patients with rectal cancer (RC) were collected utilizing SEER*Stat software (version 8.3.9). The inclusion criteria for this study were as follows: patients diagnosed with rectal adenocarcinoma through biopsy, staged at T3-4 or N + and M0, who underwent radical surgery followed by adjuvant chemotherapy between 2010 and 2014. Exclusion criteria consisted the following: (1) diagnosis of signet-ring cell carcinoma, mucinous adenocarcinoma, or multiple carcinomas, (2) receipt of intraoperative or adjuvant radiotherapy, and (3) incomplete follow-up data.
Tumor size was defined as the maximum diameter of the tumor according to the SEER database. Additional data collected included age (≤ 65 years, > 65 years), sex (male, female), marital status [21] (unmarried, married), serum CEA level (≤ 5ng/ml, >5ng/ml), differentiation grade (I/II, III/IV), T stage (T1-2, T3, T4), N stage (N0, N1, N2), stage (II, III), perineural invasion (PNI) status, presence of tumor deposits (TD), number of dissected lymph nodes (LND, < 12, ≥12), and survival time (months).
Outcome definition
The primary outcome measured for this study was overall survival (OS), which was defined as the time interval from the date of diagnosis to either the date of death or the latest follow-up.
Propensity score matching
To mitigate potential selection bias, we employed propensity score matching (PSM) analysis in this study. As previously reported, the baseline characteristics of the two groups were matched using a 1:1 nearest neighbor matching method, with a standard deviation of 0.2 [22]. This approach was implemented to ensure comparability between the groups and minimize confounding factors.
The minimum P value method
Similar to other solid cancers [13–15], we employed a dichotomous approach to determine the cut-off value for tumor size, instead of using trichotomous or quartile divisions. With the exception of tumors larger than 8 cm, the remaining cases were grouped in 1-cm intervals. The optimal cutoff value for tumor size was determined using the minimum p-value method, as previously reported [23, 24].
Statistical analyses
The baseline characteristics between groups were compared using the chi-square (χ2) test or Fisher’s test. OS was analyzed using the Kaplan-Meier (K-M) method, and differences between the groups were assessed using the log-rank test. Independent risk factors for OS were identified using multivariate Cox regression model following univariate regression analysis.
All statistical analyses were performed using RStudio (version 1.3.1073) in this study. The following packages were utilized: xlsx, table1, survival, survminer, and MatchIt. A significance level of p < 0.05 (two-sided) was considered statistically significant in this study.
Results
Patients’ characteristics
Initially, a total of 1402 patients with LARC were included in this study. Among them, 1,105 patients (78.8%) received preoperative radiotherapy (RT + S group), while 297 patients (21.2%) underwent surgery alone (S group). Increased percentages of patients aged ≤ 65, male gender, elevated CEA levels, stage II disease, T3 tumors, N0 status, and larger tumor size were observed in the RT + S group compared to the S group (all P < 0.05, Table 1). Conversely, the rates of PNI, TD, and number of LND ≥ 12 were lower in the RT + S group (all P < 0.05, Table 1). However, following a 1:1 PSM analysis, no significant differences were observed between the two groups in terms of baseline characteristics (all P > 0.05, Table 1).
Table 1.
Patient demographics and clinicopathologic characteristics
| Before PSM | After PSM | |||||
|---|---|---|---|---|---|---|
| S | RT + S | P-value | S | RT + S | P-value | |
| (N = 297) | (N = 1105) | (N = 257) | (N = 257) | |||
| Age (years) | ||||||
| ≤ 65 | 214 (72.1%) | 884 (80.0%) | 0.004 | 189 (73.5%) | 171 (66.5%) | 0.102 |
| > 65 | 83 (27.9%) | 221 (20.0%) | 68 (26.5%) | 86 (33.5%) | ||
| Sex | ||||||
| Male | 165 (55.6%) | 699 (63.3%) | 0.019 | 144 (56.0%) | 148 (57.6%) | 0.789 |
| Female | 132 (44.4%) | 406 (36.7%) | 113 (44.0%) | 109 (42.4%) | ||
| Marital status | ||||||
| Unmarried | 97 (32.7%) | 425 (38.5%) | 0.077 | 88 (34.2%) | 109 (42.4%) | 0.070 |
| Married | 200 (67.3%) | 680 (61.5%) | 169 (65.8%) | 148 (57.6%) | ||
| CEA (ng/ml) | ||||||
| ≤ 5 | 193 (65.0%) | 645 (58.4%) | 0.046 | 162 (63.0%) | 141 (54.9%) | 0.073 |
| > 5 | 104 (35.0%) | 460 (41.6%) | 95 (37.0%) | 116 (45.1%) | ||
| Stage | ||||||
| II | 61 (20.5%) | 335 (30.3%) | 0.001 | 60 (23.3%) | 61 (23.7%) | 1.000 |
| III | 236 (79.5%) | 770 (69.7%) | 197 (76.7%) | 196 (76.3%) | ||
| T stage | ||||||
| T1-2 | 77 (25.9%) | 73 (6.6%) | < 0.001 | 47 (18.3%) | 47 (18.3%) | 0.589 |
| T3 | 188 (63.3%) | 926 (83.8%) | 180 (70.0%) | 187 (72.8%) | ||
| T4 | 32 (10.8%) | 106 (9.6%) | 30 (11.7%) | 23 (8.9%) | ||
| N stage | ||||||
| N0 | 61 (20.5%) | 335 (30.3%) | < 0.001 | 60 (23.3%) | 61 (23.7%) | 0.977 |
| N1 | 157 (52.9%) | 612 (55.4%) | 139 (54.1%) | 140 (54.5%) | ||
| N2 | 79 (26.6%) | 158 (14.3%) | 58 (22.6%) | 56 (21.8%) | ||
| Tumor size (cm) | ||||||
| Median (Q1, Q3) | 4.0(3.0, 5.5) | 4.3(3.0, 6.0) | 0.010 | 4.1(3.0, 5.5) | 4.5(3.0, 5.7) | 0.245 |
| Tumor differentiation | ||||||
| Grade I/II | 249 (83.8%) | 975 (88.2%) | 0.055 | 218 (84.8%) | 232 (90.3%) | 0.082 |
| Grade III/IV | 48 (16.2%) | 130 (11.8%) | 39 (15.2%) | 25 (9.7%) | ||
| PNI | ||||||
| Absent | 239 (80.5%) | 963 (87.1%) | 0.005 | 211 (82.1%) | 223 (86.8%) | 0.181 |
| Present | 58 (19.5%) | 142 (12.9%) | 46 (17.9%) | 34 (13.2%) | ||
| TD | ||||||
| Negative | 228 (76.8%) | 945 (85.5%) | < 0.001 | 205 (79.8%) | 195 (75.9%) | 0.339 |
| Positive | 69 (23.2%) | 160 (14.5%) | 52 (20.2%) | 62 (24.1%) | ||
| Number of LND | ||||||
| < 12 | 37 (12.5%) | 323 (29.2%) | < 0.001 | 37 (14.4%) | 53 (20.6%) | 0.082 |
| ≥ 12 | 260 (87.5%) | 782 (70.8%) | 220 (85.6%) | 204 (79.4%) | ||
CEA, carcinoembryonic antigen; PNI, perineural invasion; TD, tumor deposits; LND, dissected lymph nodes; S, surgery; RT, radiotherapy; PSM, propensity score matching
Preoperative RT on OS
The median OS showed a trend favoring the RT + S group compared to the S group, with a pooled hazard ratio (HR) of 0.77 (95% confidence interval [CI] = 0.60-1.00, P = 0.052, Fig. 1A). The survival rates at 3 and 5 years were 89.27% and 82.82% for the RT + S group, respectively, compared to 82.82% and 73.78% for the S group (P = 0.030 and P = 0.226, respectively). However, the survival difference between the groups became non-significant in the matched cohort (HR = 0.82, 95% CI = 0.57–1.17, P = 0.270, Fig. 1B). The 3-year survival rates were 89.46% for the RT + S group and 83.26% for the S group, while the 5-year survival rates were 77.64% and 74.02%, respectively.
Fig. 1.
Overall survival of locally advanced rectal cancer before (A) and after PSM (B). S, surgery; RT, radiotherapy; PSM, propensity score matching
Effect of tumor size on OS and its optimal cutoff point
To minimize the impact of different cutoff values for tumor size, we initially took tumor size as a continuous variable. In the crude cohort, several factors including age, sex, CEA level, stage, tumor differentiation, PNI, TD, number of LND, and tumor size, showed significant associations with OS in univariate Cox regression analysis (all P < 0.05, Table 2). Subsequently, tumor size was identified to be an independent risk factor of OS using multivariate Cox regression. After PSM, tumor size remained to be one of the independent risk factors of OS while accounting for other variables (HR = 1.08, 95%CI = 1.01–1.15, P = 0.020; Table 2).
Table 2.
Multivariate analysis on OS of LARC patients
| Before PSM | After PSM | |||
|---|---|---|---|---|
| Characteristics | HR (95% CI) | P-value | HR (95% CI) | P-value |
| Age (> 65 years) | 1.96(1.54,2.49) | < 0.001 | 2.42(1.68,3.49) | < 0.001 |
| Sex (female) | 0.68(0.53,0.87) | 0.002 | – | – |
| Marital status (married) | – | – | – | – |
| CEA (> 5 ng/ml) | 1.42(1.13,1.78) | 0.003 | 1.59(1.10,2.31) | 0.014 |
| Stage (III) | 1.26(0.95,1.69) | 0.109 | – | – |
| Tumor size* (every numerical values increase) | 1.05(1.00,1.09) | 0.037 | 1.08(1.01,1.15) | 0.020 |
| Tumor differentiation (III/IV) | 1.63(1.22,2.17) | 0.001 | – | – |
| PNI (present) | 2.13(1.61,2.80) | < 0.001 | 1.64(1.04,2.57) | 0.033 |
| TD (positive) | 1.57(1.18,2.08) | 0.002 | 1.52(1.01,2.30) | 0.047 |
| Number of LND (≥ 12) | 0.77(0.61,0.99) | 0.038 | – | – |
| Preoperative radiotherapy (RT + S) | – | – | – | – |
OS, overall survival; LARC, locally advanced rectal cancer; PSM, propensity score matching; HR, hazard ratio; CI, confidence interval; CEA, carcinoembryonic antigen; PNI, perineural invasion; TD, tumor deposits; LND, dissected lymph nodes; RT, radiotherapy; S, surgery
*Analysis as a continuous variable
Using the minimum p-value approach, we determined 5 cm as the optimal cut-off value for tumor size, which demonstrated a HR of 1.33 (95%CI = 1.05–1.67, Table 3) in the crude cohort, which was consistent with the matched cohort (Table 3). Further analysis revealed that patients with tumors > 5 cm exhibited elevated CEA levels and advanced stage compared to those with tumors ≤ 5 cm (Appendix Table 1). Additionally, tumor size, when treated as a dichotomous variable, remained an independent risk factor for OS both before and after PSM (both p < 0.05, Appendix Table 2).
Table 3.
The p-values of log-rank test and HR values for OS of each dichotomy size cutoff
| Cutoffs | Before PSM | After PSM | ||
|---|---|---|---|---|
| HR (95%CI) | P-value | HR (95%CI) | P-value | |
| 1 cm | 2.69(0.86,8.38) | 0.088 | 2.59(0.36,18.54) | 0.343 |
| 2 cm | 1.20(0.84,1.72) | 0.312 | 2.03(0.95,4.36) | 0.069 |
| 3 cm | 1.16(0.91,1.49) | 0.231 | 1.62(1.05,2.50) | 0.029 |
| 4 cm | 1.27(1.01,1.59) | 0.037 | 1.50(1.04,2.15) | 0.029 |
| 5 cm | 1.33(1.05,1.67) | 0.017 | 1.74(1.21,2.49) | 0.003 |
| 6 cm | 1.32(1.02,1.72) | 0.038 | 1.50(0.99,2.28) | 0.056 |
| 7 cm | 1.20(0.87,1.66) | 0.271 | 1.23(0.72,2.12) | 0.444 |
| 8 cm | 1.21(0.80,1.82) | 0.366 | 1.19(0.60,2.36) | 0.606 |
OS, overall survival; PSM, propensity score matching; HR, hazard ratio; CI, confidence interval.
Effect of preoperative RT on patients with tumor size > 5 cm
In the matched cohort comprising 163 patients with tumor size > 5 cm, there were 90 patients (55.2%) in the S group and 73 patients (44.8%) in the RT + S group. The baseline characteristics of the S group and the RT + S group did not exhibit significant differences (all p > 0.05, Appendix Table 3). Notably, a significant difference was observed between the RT + S and S subgroups, with a HR of 0.45 (95% CI = 0.24–0.82, P = 0.007; Fig. 2A), indicating improved survival rates at 3 and 5 years in the RT + S subgroup (3-year survival: 88.92% vs. 72.22%; 5-year survival: 77.58% vs. 59.41%, respectively). Moreover, multivariate analysis demonstrated that preoperative RT was an independent protective factor of OS among patients with tumor size > 5 cm (HR = 0.39, 95% CI = 0.21–0.71, P = 0.002; Table 4).
Fig. 2.
Effect of preoperative radiotherapy on patients with different tumor sizes. A Tumor size > 5 cm; B Tumor size ≤ 5 cm
Table 4.
Multivariate analysis of overall survival in patients with different tumor sizes
| Characteristics | Tumor size ≤ 5.0 cm | Tumor size >5.0 cm | ||
|---|---|---|---|---|
| HR (95% CI) | P-value | HR (95% CI) | P-value | |
| Age (> 65 years) | 2.21(1.36,3.57) | 0.001 | 2.30(1.30,4.06) | 0.004 |
| Sex (female) | – | – | – | – |
| Marital status (married) | – | – | – | – |
| CEA (> 5 ng/ml) | 1.83(1.13,2.97) | 0.015 | – | – |
| Stage (III) | – | – | – | – |
| Tumor differentiation (III/IV) | – | – | – | – |
| PNI (present) | 1.78(0.99,3.21) | 0.054 | – | – |
| TD (positive) | 1.69(0.98,2.94) | 0.061 | – | – |
| Number of LND (≥ 12) | – | – | 0.43(0.22,0.85) | 0.014 |
| Preoperative RT (RT + S) | – | – | 0.39(0.21,0.71) | 0.002 |
HR, hazard ratio; CI, confidence interval; CEA, carcinoembryonic antigen; PNI, perineural invasion; TD, tumor deposits; LND, dissected lymph nodes; RT, radiotherapy; S, surgery
Effect of preoperative RT on patients with tumor size ≤ 5 cm
In the matched cohort comprising 351 patients with tumor size ≤ 5 cm, there were 167 patients (47.6%) in the S group and 184 patients (52.4%) in the RT + S group. Notably, there were no significant differences in baseline characteristics between the S group and RT + S group (all P > 0.05, Appendix Table 3). Unexpectedly, the RT + S group exhibited a slightly weaker survival advantage compared to the S group in terms of overall survival (HR = 1.28, 95% CI = 0.80–2.06, P = 0.306; Fig. 2B). Among patients with tumor ≤ 5 cm, age greater than 65 and elevated CEA levels were found to be independently associated with OS (both P < 0.05, Table 4).
Subsequently, patients with tumor size ≤ 5 cm were categorized into a low-risk group, comprising those without either of the two risk factors, and a high-risk group, comprising those with at least one of the two risk factors. Figure 3A illustrates the distinct survival curves observed between the low-risk and high-risk subgroups (HR = 1.94, 95%CI = 1.17–3.22, P = 0.01). Further analysis revealed that within the low-risk subgroup, patients who received RT + S had a worse prognosis compared to those who underwent surgery alone (HR = 3.50, 95%CI = 1.37–8.95, P = 0.005; Fig. 3B). However, within the high-risk subgroup, no significant differences were observed in the median overall survival between the two groups (HR = 0.71, 95% CI = 0.40–1.24, P = 0.227; Fig. 3C).
Fig. 3.
Subgroup analysis of overall survival for patients with tumor size ≤ 5 cm. A Risk stratification (low-risk group vs. high-risk group); B preoperative radiotherapy (RT) for low-risk patients and C preoperative radiotherapy for high-risk patients. S, surgery
Discussion
Controversies surrounding the survival benefit of preoperative RT have persisted [2–4]. The crucial question lies in identifying the individuals who are likely to derive survival advantages from this treatment modality. In this study, we selected 5 cm as the optimal cutoff value of tumor size. Further, we found that patients with tumor size > 5 cm would unequivocally benefit from preoperative RT. Conversely, patients with tumor size ≤ 5 cm and without additional risk factors may not require preoperative RT.
Clinical trials such as CAO/ARO/AIO-94 [25] and NSABP-R03 [26] have emphasized the use of preoperative RT in the management of LARC to enhance R0 resection, sphincter preservation, and local control. Subsequent trials incorporating intensified modalities, including irinotecan [27], induction/consolidation chemotherapy [5, 6, 28], and immunotherapy [8], have yielded significant increases in the rate of pathological complete response (pCR). However, the achievement of long-term survival benefits has remained elusive. In our study, we observed distinct survival patterns between the RT + S and S groups before and after PSM, although it lacked statistical significance (both P > 0.05), which might be attributed to insufficient sample size as raised by Fokas et al. [29]. Alernatively, there may be a subset of patients who do not derive a survival advantage from preoperative RT. Therefore, the identification of a biomarker for screening LARC patients who would benefit from preoperative RT in terms of survival is a pressing concern.
Tumor size plays a significant role in the progression, management, and prognosis of various cancers [13–15]. While the prognostic value of tumor size has been established in CRC [16–18], it has not been formally incorporated into current staging systems. Our study consistently demonstrated the independent prognostic significance of tumor size for OS as a continuous variable before and after PSM (P < 0.05). These findings highlighted the substantial impact of tumor size on the prognosis of LARC. Therefore, we speculated that tumor size might be taken into consideration when making treatment decisions. In line with current practices for solid cancers [13–15], tumor size as a categorical variable is widely utilized in existing staging systems. Various cutoff values, such as 3 cm [30], 4 cm [31], 5 cm [16], and 6 cm [20], have been proposed, but the optimal cutoff value remains uncertain. In this study, we identified 5 cm as the optimal cutoff value of tumor size via the minimum P value method, which was further validated in the matched cohort. Consistent with previous reports [16, 17], patients with tumor size > 5 cm in our study exhibited higher levels of elevated CEA and advanced disease stage (all P < 0.05). Thus, 5 cm held a promise as a clinically relevant cutoff value for LARC patients.
Evidences revealed that larger tumor size was often associated with more aggressive characteristics and an increased risk of recurrence and metastasis [16, 17, 32–34], making it a potential target for preoperative RT. Our study demonstrated that preoperative RT had a significant positive impact on OS in patients with tumor size > 5 cm. Furthermore, multivariate Cox regression analysis identified preoperative RT as one of the three independent risk factors for OS (P < 0.05). Based on these findings, we recommended preoperative RT as a beneficial treatment strategy for patients with tumor size > 5 cm.
When considering small tumors, the situation becomes more complex. Majority of the published reports revealed that small tumors were associated with favorable biological behavior and a good prognosis in CRC [16, 17, 32–34]. However, aggressive characteristics have also been observed in very small tumors in several studies [19, 20]. In our study, we found that patients with tumor size ≤ 5 cm had normal levels of CEA and were diagnosed at early stages. Interestingly, preoperative RT did not provide any survival benefit to these patients, suggesting that some of them may not require preoperative RT. Multivariate Cox analysis identified age and CEA as the only two independent risk factors in patients with tumor size ≤ 5 cm (both P < 0.05). Further, we found that preoperative RT had a detrimental effect on the OS of patients with tumor size ≤ 5 cm and neither of risk factors. However, among patients with tumor size ≤ 5 cm and risk factors, there was no significant difference in OS between the RT + S group and the S group (P > 0.05). Therefore, we concluded that patients with tumor size ≤ 5 cm might not require preoperative radiotherapy in terms of OS, which needs further investigation.
There were several limitations in this study. First, the retrospective design of the study introduces inherent selection and recall biases. Second, important factors such as the details of adjuvant chemotherapy, including the specific regimen and duration, which could also influenced the prognosis of rectal cancer [35], were not available in the SEER database. To mitigate this bias, we focused on patients who received adjuvant chemotherapy between 2010 and 2014. Thirdly, data on preoperative RT, including radiation regimen, down-staging, pCR, and sphincter preservation, were not accessible in the SEER database. The absence of this information may weaken the conclusions drawn from this study. Last but not least, it should be noted that tumor diameter, as a one-dimensional measurement, may not fully capture the actual tumor size [36]. In the future, the use of primary gross tumor volume could serve as an ideal surrogate for tumor size, enabling a more accurate prediction of treatment response and long-term prognosis [37].
Conclusion
Data from this retrospective analysis of patients with LARC seems to indicate that tumor size might play a role in the decision-making process for (tumors > 5 cm) or against (tumors ≤ 5 cm) preoperative radiotherapy.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Author contributions
Conception and design: XHZ, HQL, QZH, LW and JXW. Administrative support: LW and JXW. Provision of study materials or patients: XHZ, HQL and QZH. Collection and assembly of data: XHZ, HQL and QZH. Data analysis and interpretation: XHZ, HQL and QZH. Manuscript writing: XHZ, HQL, QZH, LW and JXW. Final approval of manuscript: XHZ, HQL, QZH, LW and JXW.
Funding
This research was funded by Fujian Province Gastrointestinal, Respiratory, Genitourinary Malignant Tumor Radiotherapy Radiation and Treatment Clinical Medical Research Center (2021Y2014), Fujian Provincial Clinical Medical Research Center for Tumor Precision Radiotherapy (2020Y20101), Fujian Province Science and Technology Innovation Joint Funding Project (2021Y9216), Fujian Province Natural Science Foundation (2021J01438 and 2022J01433), Fujian Cancer Hospital In-Hospital Funding Program (2022YNG06 and 2023YNPT00), the Fujian Provincial Clinical Research Center for Cancer Radiotherapy and Immunotherapy (2020Y2012), and the National Clinical Key Specialty Construction Program.
Data availability
The datasets for this study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
Not available. The data of this study was obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Informed consent and ethical approval were waived since the data were publicly available.
Consent for publication
Not Applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Xiaohong Zhong, Huaqin Lin and Qizhen Huang have contributed equally to this work.
Contributor Information
Lei Wang, Email: wangleiy001@126.com.
Junxin Wu, Email: junxinwufj@aliyun.com.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets for this study are available from the corresponding author on reasonable request.