Implications for pelvic lymph node irradiation in definitive chemoradiotherapy of node negative muscle invasive bladder cancer based on predictive factors of clinicopathologic discrepancy

Abstract

Purpose: To identify pre-surgical imaging predictive value and factors associated with the clinicopathologic discrepancy for implication of definitive pelvic radiotherapy in clinically node-negative bladder cancer.

Method: The documented data of bladder cancer patients who underwent radical cystectomy plus pelvic lymphadenectomy were collected retrospectively. Patients' characteristics, last imaging, pathology reports, disease-specific survival and overall survival were retrieved.

Results: From 142 patients, pre-surgical imaging had a sensitivity of 76.4%, specificity of 73.7%, positive predictive value (PPV) of 94.9%, and negative predictive value (NPV) of 32.6% (p value < 0.0001) for detection of muscle invasion. Also, for detection of positive lymph nodes, imaging had a sensitivity of 31.8%, specificity of 85.7%, PPV of 50%, and NPV of 73.7% (p value: 0.022). 44.4% of study population were upstaged after surgery (24.6% associated with N-upstaging) and 18.3% were downstaged (12% associated with N-downstaging). Receipt of neoadjuvant chemotherapy and T-stage were not correlated with N-upstaging. On multivariate analysis, lymphovascular invasion (LVI) maintained its significance for independent prediction of upstaging (OR 3.3, 95% CI 1.5-7.5, p value: 0.004) and inversely with downstaging (OR 0.34, 95% CI 0.12-0.96, p value: 0.04). Older age (OR 1.03, 95% CI 1.0-1.05, p value 0.047), positive margins (OR 2.1, 95% CI 1.2-3.8, p value 0.011), presence of LVI (OR 2.5, 95% CI 1.4-4.7, p value 0.003), perineural invasion (OR 2.0, 95% CI 1.2-3.4, p value 0.013), and lymph node ratio (OR 1.011, 95% CI 1.001-1.021, p value 0.03) were associated with worse survival. Also, N-upstaging independently predicted a worse survival after controlling for surgical pathology stage (OR 2.3, 95% CI 1.2-4.5, p value 0.011).

Conclusions: The optimal target volume in definitive chemoradiotherapy of node-negative bladder cancer patients remains to be established. Since then, customizing the treatment is considered especially for positive LVI in TURBT specimen.

Keywords: Bladder cancer; Chemoradiotherapy; Lymphovascular invasion; Pelvic lymph nodes.