The following are predisposing factors for esophageal Ca Except -
Plummer-Vinson syndrome
Tylosis palmaris
Chronic Achalasia
Benzene therapy
Predisposing factors for Ca Esophagus 

For Adenocarcinoma

Chronic gastric reflux (i,e Barrett's esophagus)

For Squamous cell Ca
Alcohol
Cigarette
Mucosal damage from physical agents → Hot tea, Lye ingestion, Radiation-induced strictures, Chronic achalasia
Other ingested carcinogens → Nitrates, Smoked opiates, Fungal toxins in pickled vegetables
Plummer -Vinson - Paterson Kelly syndrome ( Esophageal Web + glossitis + Iron deficiency )
Tylosis palmaris et plantaris ( Congenital hyperkeratosis and pitting of palms and soles)
Dietary deficiencies of molybdenum, Zinc, Vitamin A.
Celiac sprue
Chronic Achalasia

Following information has been added in 8th/e of Robbins 

Human papillomavirus (HPV) infection has also been implicated in esophageal squamous cell carcinoma in high-risk areas but not in low-risk regions.