Abstract
RATIONALE: Treatment strategies for rectal squamous cell carcinoma (rSCC) are yet to be established, given its rarity. Although squamous cell carcinoma has been reported to be highly sensitive to cetuximab and radiation, there is no report of combination therapy of cetuximab and radiation for rSCC. In this study, we firstly reported a case of rSCC in which a complete response was achieved with the original chemoradiotherapy comprising oxaliplatin, S-1, cetuximab, and simultaneous radiation. PATIENT CONCERNS: A 46-year-old women presented to our hospital with lower abdominal pain and fatigue. DIAGNOSES: Based on tumor marker analyses, histological examination of biopsy specimens, and comprehensive imaging, the patient was diagnosed with rSCC. INTERVENTIONS: Neoadjuvant chemoradiotherapy (50.4 Gy) was administered in 28 fractions, along with concurrent chemotherapy comprising SOX (S-1: 80 mg/m2, days 1-5 and 8-12, oxaliplatin: 85 mg/m2, day 1) and cetuximab (400 mg/m2, day 1, 250 mg/m2, after day 8). OUTCOMES: Five weeks after chemoradiation, the patient underwent laparoscopic partial intersphincteric resection, achieving a complete pathological response. LESSONS: This case firstly highlights the usefulness of SOX plus cetuximab combined with radiation in the treatment of locally advanced rSCC. However, a large-scale study is required to establish safe and effective treatment regimens.