Prognostic role of ultrasonography staging in patients with anal cancer

BACKGROUND Carcinomas of the anal canal are staged according to the size and extent of the disease; however, we propose including a novel ultrasound (US) staging system, based on depth of tumor invasion. In this study the clinical American Joint Committee on Cancer (AJCC) staging guidelines and the US classificationss in patients with anal cancer were compared. AIM To evaluate the prognostic role of the US staging system in patients with anal cancer. METHODS The data of 48 patients with anal canal squamous cells carcinoma, observed at our University Hospital between 2007 and 2017, who underwent pre-treatment assessment with pelvic magnetic resonance imaging (MRI), total body computed tomography (CT) scan and endoanal US were retrospectively reviewed. Anal canal tumors were clinically staged according to AJCC, determined by MRI by measurement of the longest tumor diameter, and CT scan. Endoanal US was performed with a high multi-frequency (9-16 MHz), 360 degrees rotational mechanical probe; US classification was based on depth of tumor penetration through the anal wall, according to Giovannini's study. All patients were treated with definitive radiation combined with 5-fluorouracile and Mitomycin-C. After treatment patients were followed-up regularly. RESULTS At baseline there were 30 and 32 T1-2, 18 and 16 T3-4, 31 and 19 N+ patients classified according to the clinical AJCC and US staging system respectively. After a mean follow-up of 98 months, 38 patients (79.1%) are alive and 28 (58.3%) are disease free. During follow up 20 patients (41.6%) experienced recurrences. After univariate analysis, American Society of Anesthesiologists (ASA) score (P= 0.00000001) and US staging (P= 0.009) were significantly related to disease-free survival (DFS). When overall survival and DFS functions were compared, a statistically significant difference was observed for DFS survival when the US staging was applied with respect to the clinical AJCC staging. By combining the 2 significant prognostic variables, namely the US staging with the ASA score, four risks groups with different prognoses were identified. CONCLUSION Our findings suggest that US staging may be superior to traditional clinical staging, since it is significantly associated with DFS in anal cancer patients.