Identification of endometrial cancer recurrence – a validated algorithm based on nationwide Danish registries

Figures & data

Figure 1. Flowchart of study population.

Figure 2. Schematic overview of the algorithm to identify women diagnosed with recurrence of endometrial cancer. *Hysterectomy and salpingo-oophorectomy or oophorectomy ±adjuvant chemotherapy and/or radiotherapy. **Until the last of the following dates: (1) 90 days after surgery or (2) 90 days after completed adjuvant therapy. Evidence of persistent malignant disease was evaluated based on registrations of pathology results, procedure codes, and diagnosis codes. Adapted from Rasmussen et al. [12].

Table 1. Concordance of endometrial cancer recurrence between gold standard and algorithm.

	Recurrence by gold standard
	Yes	No	Total
Recurrence by algorithm
Yes	146	9	155
No	14	99	113
Total	160	108	268

Table 2 . Performance of the algorithm to identify endometrial cancer recurrence in 268 women with early-stage endometrial cancer.

	All indicators combined	Indicators stratified on codes related to pathology, procedure, and diagnosis
Algorithm performance	% (95% CI^d)	Pathology codes^a	Procedure codes^b	Diagnosis codes^c
		% (95% CI)	% (95% CI)	% (95% CI)
Sensitivity	91.3 (85.8–95.1)	71.3 (63.6–78.1)	66.3 (58.4–73.5)	28.8 (21.9–36.4)
Specificity	91.7 (84.8–96.1)	96.3 (90.8–99.0)	96.3 (90.8–99.0)	96.3 (90.8–99.0)
Positive predictive value	94.2 (89.3–97.3)	96.6 (91.5–99.1)	96.4 (91.0–99.0)	92.0 (80.8–97.8)
Negative predictive value	87.6 (80.1–93.1)	69.3 (61.3–76.6)	68.5 (57.9–73.2)	47.7 (40.9–54.6)

^a Histology coded as recurrent and histology similar to primary cancer histology and coded as metastatic or direct spread to surrounding tissue.

^b Laparotomy, omentectomy, lymphadenectomy, radiotherapy, and chemotherapy.

^c Metastasis (ICD-10: C76-C79 (except C779), CxxxM) and recurrence (ICD-10: C549X).

^d CI: confidence interval.

Table 3. Concordance of cancer recurrence date between gold standard and algorithm.

	% (95% CI)
Same date	6 (3–12)
≤7 days	41 (33–49)
≤30 days	86 (80–91)
≤60 days	94 (90–97)

Rasmussen LA, Jensen H, Virgilsen LF, et al. A validated algorithm for register-based identification of patients with recurrence of breast cancer-based on Danish Breast Cancer Group (DBCG) data. Cancer Epidemiol. 2019;59:129–134.

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