ESTRO 2024 - Abstract Book

S2577

Clinical - Urology

ESTRO 2024

One-hundred and fifty-one patients met our inclusion criteria. Two patients with no prostatic lesion on MRI were excluded. A total of 149 patients were analysed. The baseline patient and tumour characteristics and number and location of the PSMA avid lymph nodes are summarised in Table 1.

The location of the DIL was lateralised in 55/149 (37%) of patients; right and left-sided in 28/149 (19%) patients and 27/149 (18%) patients respectively. There were 43/149 (29%) patients with bilateral, right-sided predominance DIL, 23/149 (15%) patients with bilateral, left-sided predominance DIL, and 28/149 (19%) patients with bilateral and no predominance DIL. There were 93/149 (62%) patients who had seminal vesicle involvement. Of those, 53/149 (36%) patients had bilateral seminal vesicle involvement, 17/149 (11%) patients and 23/149 (15%) patients had left and right seminal vesicle involvement respectively. Regarding lymph node distribution, the associations with the location of the DIL are shown in Figure 1 , suggesting there is not a strong correlation between DIL position and laterality of nodal metastases. The majority of patients (47/53, 87%) with para-aortic nodal involvement, defined as nodes up to the L1/L2 vertebral space, had disease extending from apex to mid gland, and around 70% of patients (38/53) with para-aortic nodal involvement had seminal vesicle involvement. The majority of these patients had bilateral seminal vesicle involvement (26/38). Patients with right-sided pelvic nodal metastases (common iliac, external, internal iliac, and obturator) had predominant involvement of the right seminal vesicle (57%). Similarly, patients with left-sided pelvic nodal metastases had predominant involvement of the left seminal vesicle (56%). A high proportion of patients (72%) with mesorectal lymph nodes had apical disease.