Calcitriol in Preventing Lung Cancer in Smokers and Former Smokers at High Risk of Lung Cancer

DISEASE CHARACTERISTICS: * Pathologically confirmed squamous metaplasia or squamous dysplasia of the lungs by autofluorescence bronchoscopy within the past 5 years * Must be a current or former smoker * No evidence of concurrent disease with lung cancer or head and neck cancer * History of treated lung cancer or head and neck cancer treated with curative intent allowed, provided that there has been no evidence of disease for \> 1 year PATIENT CHARACTERISTICS: * ECOG performance status 0-1 * Total granulocyte count \> 1,500 x 10\^9cells/L * Platelet count \> 100,000 x 10\^9cells/L * Calculated Creatinine clearance \> 60 mL/min (using the Cockcroft-Gault formula) * Calcium concentration 50-300 mg/24 hours * Total bilirubin 0.2-1.3 mg% * ALT/AST ≤ 2.5 times upper limit of normal (ULN) * Alkaline phosphatase ≤ 2.5 times ULN * Albumin ≥ 2.5 g/dL * Ionized serum calcium normal (1.19-1.29 mmol/L) * Corrected serum calcium ≤ 10.2 mg/dL * Willing to attend all scheduled study visits, complete all study questionnaires, and allow biological specimen collection, including a bronchoscopy * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for at least 1 month after completion of study therapy * No life-threatening medical conditions that would preclude bronchoscopy, including but not limited to, any of the following: * Acute cardiac failure * Uncontrolled hypertension * Uncontrolled diabetes mellitus * Unstable coronary artery disease * No severe metabolic disorders that would preclude calcitriol administration * No history of any other malignancy within 3 years except for nonmelanoma skin cancer or cervical carcinoma in situ * No history or evidence of kidney stones * No patients who are susceptible to calcium-related dysrhythmias * No known hypersensitivity to calcitriol * No known allergies to tree nuts (i.e., almonds) PRIOR CONCURRENT THERAPY: * At least 2 months since prior and no concurrent calcium supplements * Concurrent multivitamin supplement allowed provided the amount of vitamin D in the supplement is not in excess of the recommended daily dose * No concurrent thiazides, phenobarbital, or digitalis * No concurrent digoxin * No concurrent bile acid binding drugs (i.e., cholestyramine, colestipol) * No concurrent danazol or aluminum-based antacids * No concurrent ketoconazole or other azole antifungals