Examining the Relationship and Prognostic Significance of Cell-Free DNA Levels and the PSMA-Positive Tumor Volume in Men with Prostate Cancer: A Retrospective–Prospective [68Ga]Ga-PSMA-11 PET/CT Study

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FIGURE 1.
CONSORT (Consolidated Standards of Reporting Trials) diagram.
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FIGURE 2.
Scatterplot illustrating correlations between cfDNA concentrations and PSMA-TV in all, hsPC, and CRPC patients. PSMA-TV levels have been logarithmically transformed (log² n) for scale comparability.
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FIGURE 3.
Lollipop plots illustrating correlations between cfDNA and PSMA-TV with several variables. HB = hemoglobin.
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FIGURE 4.
Violin plots showing relationship between cfDNA concentrations and PSMA-TV quartiles for all (A) and CRPC (B) patients. Bar plots illustrate frequency of dominant tumor lesion fraction according to PSMA-TV quartiles in all (C) and CRPC (D) patients. LN = lymph node.
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FIGURE 5.
Kaplan–Meier curves illustrating survival probabilities between high- and low-cfDNA groups (A), high- and low–PSMA-TV groups (B), and compound-stratified groups (C).

TABLE 1.

Demographic and Clinical Patient Data

Variable	hsPC (n = 74)	CRPC (n = 74)
Age at inclusion (y)	69.9 ± 7.8 (50.0–85.0)	71.5 ± 7.5 (49.0–85.0)
Tracer dose (MBq)	185.6 ± 20.7 (134.0–300.0)	184.3 ± 17.1 (149.0–263.0)
cfDNA (ng/μL)	0.745 ± 0.654 (0.0009–4.25)	1.04 ± 1.42 (0.0818–9.49)
PSMA-TV (cm³)	14.2 ± 76.7 (0.0–659.1)	175.5 ± 369.2 (0.0–1,597.7)
PSMA-positive lesion
Any lesion	51 (68.9%)	64 (86.5%)
Prostate lesion	25 (33.8%)	19 (25.7%)
Lymph node lesion	26 (35.1%)	37 (50.0%)
Bone lesion	14 (18.9%)	48 (64.9%)
Organ lesion	4 (5.4%)	13 (17.6%)
Dominant fraction
Prostate	19 (25.7%)	5 (6.8%)
Lymph node	22 (29.7%)	19 (25.7%)
Bone	8 (10.8%)	39 (52.7%)
Organ	2 (2.7%)	1 (1.4%)
PSA (ng/dL)^*	24.98 ± 105.34 (0.09–761.0)	186.42 ± 618.29 (0.01–3,689.0)
Hemoglobin (g/dL)^†	14.06 ± 1.64 (12.1–17.8)	11.96 ± 1.84 (7.8–15.4)
Lactate dehydrogenase (U/L)^‡	201.21 ± 47.37 (149.0–312.0)	250.05 ± 229.26 (130.0–1,573.0)
Systemic therapies while PET
Antihormonal therapies	4 (5.41%)	55 (78.57%)
Cytotoxic therapies	1 (1.35%)	3 (16.67%)
Systemic therapies after PET
Local	24 (55.8%)	10 (23.3%)
Local + ADT	6 (14.0%)	—
ADT	9 (20.9%)	14 (32.6%)
CHT	1 (2.3%)	2 (4.7%)
CHT + ADT	1 (2.3%)	—
¹⁷⁷Lu-PSMA	1 (2.3%)	16 (37.2%)
Study	1 (2.3%)	1 (2.3%)
Mean follow-up (mo)	19.8 ± 13.5 (0.0–47.9)	16.0 ± 14.0 (0.0–49.0)

↵* n = 14 and 11 data missing in hsPC and CRPC groups, respectively.
↵^† n = 59 and 35 data missing in hsPC and CRPC groups, respectively.
↵^‡ n = 60 and 36 data missing in hsPC and CRPC groups, respectively.
ADT = androgen deprivation therapy; CHT = concurrent hormone therapy.
Qualitative data are number and percentage; continuous data are mean ± SD and range. Local disease comprised prostate and seminal vesicle lesions.

TABLE 2.

Unpaired Kruskal–Wallis Distribution of PSMA-TV Quartiles and Corresponding cfDNA Concentrations for Overall and CRPC Patient Groups

TABLE 3.

Post Hoc Adjusted Pairwise Table Displaying cfDNA Differences Between PSMA-TV Quartiles in CRPC Group

Quartile	Median difference	Mean difference	Mean difference in 95% CI	P
Q1 vs. Q2	0.18	0.11	−0.23 to 0.44	0.451
Q1 vs. Q3	−0.29	−0.7	−2.11 to 0.71	0.38
Q1 vs. Q4	−0.62	−1.1	−2.11 to −0.086	0.016
Q3 vs. Q2	0.47	0.8	−0.6 to 2.21	0.107
Q4 vs. Q2	0.8	1.21	0.2 to 2.21	0.002
Q4 vs. Q3	0.33	0.4	−1.33 to 2.13	0.146