Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) arises from squamous epithelial cells lining the esophagus, predominantly affecting the middle (50%) and upper thirds (15%) with the lower third (35%) less commonly involved (where adenocarcinoma predominates in Western countries). ESCC accounts for 90% of esophageal cancers globally but only 30-40% in Western countries (where adenocarcinoma now predominates due to GERD/Barrett's). Histologically classified as well, moderately, or poorly differentiated. Variants include verrucous carcinoma (low-grade), basaloid squamous cell carcinoma, spindle cell carcinoma, adenosquamous carcinoma. Stage by AJCC 8th edition with separate staging for SCC and adenocarcinoma using TNM, with histology-specific groupings.

Epidemiology shows striking geographic variation forming the 'esophageal cancer belt' from Northern Iran through Central Asia (Iran, Turkmenistan, Uzbekistan, Kazakhstan) to North-Central China and parts of East Africa (Kenya, Tanzania, Ethiopia). Highest age-adjusted incidence: Iran (Golestan Province) >100/100,000, Linxian China 100-180/100,000. Risk factors include smoking (4-7x risk, dose-related), heavy alcohol consumption (5-7x, synergistic with smoking >50x), low socioeconomic status, low fruit/vegetable intake, hot beverages (mate tea, very hot tea), nitrosamines in pickled foods, fungal contamination of food (Fusarium), achalasia (10x risk), Plummer-Vinson syndrome, lye/caustic stricture (decades later), prior thoracic radiation, head and neck cancer history (10-15% second primary), HPV (controversial), tylosis (rare hereditary syndrome), poor oral hygiene. Genetic alterations: TP53 (highly prevalent), CDKN2A, NOTCH1, PIK3CA, RB1.

Clinical presentation typically late: dysphagia (progressive, solids first), weight loss, retrosternal chest pain, regurgitation, odynophagia, hematemesis, hoarseness from recurrent laryngeal nerve, persistent cough, aspiration pneumonia, advanced disease with malignant fistulas (tracheoesophageal, aorto-esophageal — fatal), Horner's syndrome, vena cava obstruction. Diagnosis is by upper endoscopy with biopsy (multiple from any nodule, ulceration, or suspicious mucosa), narrow-band imaging and chromoendoscopy with Lugol's iodine (squamous cells stain dark, dysplastic/cancer cells fail to stain — 'pink sign'), endoscopic ultrasound (EUS) for T and N staging, CT chest/abdomen/pelvis, PET-CT for distant staging, bronchoscopy if airway involvement, MRI for selected cases. Treatment: T1a (intramucosal) — endoscopic resection (EMR/ESD); T1b — esophagectomy or chemoradiation; T2 N0 — surgery alone or neoadjuvant chemoradiation; T2-T4a or N+ — neoadjuvant chemoradiation with CROSS regimen (carboplatin/paclitaxel + 41.4 Gy) followed by surgery; FLOT regimen for selected GE junction tumors; definitive chemoradiation for unresectable, cervical esophageal, or surgically unfit (50.4 Gy with cisplatin/5-FU); metastatic — palliative chemotherapy (cisplatin/5-FU, FOLFOX, paclitaxel), pembrolizumab/nivolumab for PD-L1+ tumors (advanced ESCC particularly responsive — KEYNOTE-590, CheckMate 648), immunotherapy + chemotherapy combinations, anti-EGFR therapy (cetuximab, nimotuzumab) in selected cases. Esophagectomy approaches: Ivor Lewis, McKeown 3-field, transhiatal, minimally invasive. Five-year survival: T1a 85-95%, T1b 65-80%, locoregional with neoadjuvant 35-50%, metastatic 5-15%.