Identifying Optimal Candidates for Primary Tumor Resection Among Metastatic Pancreatic Cancer Patients: A Population-Based Predictive Model

Figures & data

Figure 1. Flowchart of this study. PSM: propensity score matching; Surg: surgery; ROC: receiver operating characteristic; DCA: decision curve analysis.

Table 1. Characteristics of the study population by study group before and after PSM.

Variable	Before PSM		p Value	After PSM		p Value
	Primay site resection 662	Nonprimay site resection 13,521		Primay site resection 385	Nonprimay site resection 385
Gender			0.425			0.665
Male	340	7161		188	191
Female	322	6360		197	194
Age			0.001			0.546
≤65	308	8035		191	183
>65	354	5486		194	202
Race			0.004			0.728
W	537	10,696		306	309
B	67	1832		48	43
AI	0	79		0	1
API	58	914		31	32
T Stage			0.001			0.928
T1	17	499		14	12
T2	92	4982		80	85
T3	481	5107		234	228
T4	72	2933		57	60
N Stage			0.001			0.345
N0	222	8269		174	161
N1	440	5252		211	224
Grade			0.001			0.474
G1	107	264		53	56
G2	233	1022		123	136
G3	202	1417		101	96
G4	21	118		13	6
Gx	99	10,700		95	91
Primary site			0.001			0.836
Pancreas head	323	5833		193	190
Pancreas body	64	2713		45	42
Pancreas tail	208	3085		106	104
Pancreas other	67	1890		41	49
Chemotherapy			0.034			0.714
YES	395	8626		230	225
NO/UNK	267	4895		155	160
Systemic			0.001			0.769
YES	404	379		229	223
NO/UNK	258	13,142		156	152

PSM: propensity score matching; Race (W: White; B: Black; AI: American Indian/Alaska Native; API: Asian or Pacific Islander); UNK: unknown

Figure 2. Kaplan–Meier (KM) plots show the OS and CSS of mPC patients according to the group. (A) KM curves of OS for the surgery and nonsurgery groups before PSM, (B) KM curves of CSS for the surgery and nonsurgery groups before PSM, (C) KM curves of OS for the surgery and nonsurgery groups after PSM, (D) KM curves of CSS for the surgery and nonsurgery groups after PSM (p < 0.001). Surg: Surgery.

Figure 3. Nomogram to identify beneficial candidates for primary tumor surgery. (A) Nomogram for predicting which patients with mPC might benefit from primary tumor resection. The cutoff point of the nomogram was 0.5. The patient would be a benefit candidate when the overall prediction probability exceeds the threshold and vice versa. (B) ROC curve of the training set. (C) ROC curve of the validation set. (D) Calibration curve of the training set. (E) Calibration curve of the validation set. (F) DCA of the training set. (E) DCA of the validation set. Sex (F: female; M: male), Race (W: White; B: Black; AI: American Indian/Alaska Native; API: Asian or Pacific Islander), T: T Stage; N: N stage; Primary Site (PH: Pancreas head; PB: Pancreas body; PT: Pancreas tail; PO: Pancreas other); AUC: area under the receiver operating characteristic curve.

Figure 4. Prediction nomogram of OS after primary tumor surgery. (A) The nomogram includes age, sex, race, T stage, N stage, histological grade, and tumor location for predicting OS in postoperative patients. (B) ROC curves for 1-year OS and 2-year OS in the training set. (C) ROC curves for 1-year OS and 2-year OS in the validation set. (D) Calibration curves for 1-year OS and 2-year OS in the training set. (E) Calibration curves for 1-year OS and 2-year OS in the validation set. (F) DCA for 1-year OS and 2-year OS in the training set. (G) DCA for 1-year OS and 2-year OS in the validation set. Sex (F: female; M: male), Race (W: White; B: Black; AI: American Indian/Alaska Native; API: Asian or Pacific Islander); T: T Stage; N: N stage; Primary Site (PH: Pancreas head; PB: Pancreas body; PT: Pancreas tail; PO: Pancreas other); AUC: area under the receiver operating characteristic curve; OS: overall survival.

Figure 5. Prediction nomogram of CSS after primary tumor surgery. (A) The nomogram includes age, sex, race, T stage, N stage, histological grade, and tumor location for predicting CSS in postoperative patients. (B) ROC curves for 1-year CSS and 2-year CSS in the training set. (C) ROC curves for 1-year CSS and 2-year CSS in the validation set. (D) Calibration curves for 1-year CSS and 2-year CSS in the training set. (E) Calibration curves for 1-year CSS and 2-year CSS in the validation set. (F) DCA for 1-year CSS and 2-year CSS in the training set. (G) DCA for 1-year CSS and 2-year CSS in the validation set. Sex (F: female; M: male), Race (W: White; B: Black, AI: American Indian/Alaska Native; API: Asian or Pacific Islander); T: T Stage; N: N stage; Primary Site (PH: Pancreas head; PB: Pancreas body; PT: Pancreas tail; PO: Pancreas other); AUC: area under the receiver operating characteristic curve; CSS: cancer-specific survival.

Availability of data and materials

All data generated or analyzed during this study are included in this published article and raw data can download from Surveillance, Epidemiology, and End Results (SEER) database (www.seer.cancer.gov).