MP46-09: Does time to dynamic sentinel lymph node biopsy affect recurrence-free survival in penile squamous cell carcinoma?

James A Churchill*, Ashwin Sachdeva, Allaudin Issa, Craig Jones, Noel W Clarke, Maurice W Lau, Arie S Parnham, Vijay K Sangar, Manchester, United Kingdom

Introduction: Dynamic sentinel node biopsy (DSNB) is the standard of care for invasive inguinal lymph node staging for intermediate-risk (pT1G2) and high-risk (=pT1G3) primary disease with no clinical evidence of nodal or distant metastasis (cN0). A step-wise management approach involving initial biopsy, subspecialist referral, definitive primary (penile) surgery, histology review and invasive nodal staging procedures introduces potential delays in determining final nodal staging, which is a key determinant of recommendations for further treatment. We hypothesise that time between definitive primary surgery and DSNB is associated with worse metastasis-free survival.

Methods: Retrospective data for patients treated at a single UK tertiary referral centre between 2003 and 2021 with a diagnosis of penile squamous cell carcinoma who underwent DSNB for invasive inguinal lymph node staging where analysed. Patients were excluded if primary tumour stage was  =pT1G1, nodal or distant metastatic disease was clinically suspected at diagnosis (cN+/cM+) or if DSNB was performed for recurrent local disease. The primary outcome measure of metastasis-free survival (MFS) was calculated according to time between definitive primary treatment and first DSNB. Patients were categorised as this period being less than 3 months (early) vs greater than 3 months (late). Multivariate analysis for age, stage, grade and primary surgical margin status was undertaken. We performed a sub-group analysis for patients with pT1G2 vs =pT1G3 primary disease to further stratify risk. Audit approval was obtained from the host clinical governance committee.

Results: A total of 330 patients met inclusion criteria, of which 70 were staged as pT1G2 and 260 as =pT1G3. There were no nodal or distant metastases in the pT1G2 group at 10-year follow-up. Amongst these 330, 199 patients had early DSNB and 131 had late DSNB. Baseline differences in cohort characteristics were observed in grade of disease, with 61.8% of patients in the early group having grade 3-4 disease vs 41.9% in the late group (p=0.001). After adjusting for age, stage, grade and primary surgical margin status, we noted no significant difference in MFS between early vs late DSNB (HR 0.74, 95% CI 0.12-4.40, p=0.74).

Conclusions: In our cohort of patients with no clinical suspicion of nodal disease, a delay of greater than 3 months between definitive primary surgery and DSNB was not associated with a significant difference in MFS.

Source of Funding: None