Adjuvant Chemotherapy With Gemcitabine and Cisplatin Compared to Standard of Care After Curative Intent Resection of Biliary Tract Cancer

All enrolled patients will postoperatively be assessed for eligibility for the treatment phase. Additionally patients not previously enrolled into the trial for whatever reason (e.g. incidental finding during surgery) will be evaluated for eligibility. * Histologically confirmed adenocarcinoma of biliary tract (intrahepatic, hilar or extrahepatic cholangiocarcinoma or muscle invasive gallbladder carcinoma) after radical surgical therapy with macroscopically complete resection (mixed tumor entities (HCC/CCA) are excluded) * Macroscopically complete resection (R0/1) within 6 (-16) weeks before scheduled start of chemotherapy * ECOG 0-1 * Age ≥18 years * Adequate hematologic function * Adequate liver function * Adequate renal function * No active uncontrolled infection, except chronic viral hepatitis under antiviral therapy * No concurrent treatment with other experimental drugs or other anti-cancer therapy, treatment in a clinical trial within 30 days prior to randomization * Negative serum pregnancy test within 7 days of starting study treatment in pre-menopausal women and women \<1 year after the onset of menopause (Note: a negative test has to be reconfirmed by a urine test, should the 7-day window be exceeded) Criteria for initial study enrolment * Written informed consent * No prior chemotherapy for cholangiocarcinoma * No previous malignancy within 3 years or concomitant malignancy, except: non-melanomatous skin cancer or adequately treated in situ cervical cancer * No severe or uncontrolled cardiovascular disease (congestive heart failure NYHA III or IV, unstable angina pectoris, history of myocardial infarction in the last 3 months, significant arrhythmia) * Absence of psychiatric disorder precluding understanding of information of trial related topics and giving informed consent * No serious underlying medical conditions (judged by the investigator), that could impair the ability of the patient to participate in the trial * Fertile women (\< 1 year after last menstruation) and procreative men willing and able to use effective means of contraception (oral contraceptives, intrauterine contraceptive device, barrier method of contraception in conjunction with spermicidal jelly or surgically sterile) * No pregnancy or lactation