Bile Duct Cancer - husband will be starting chemo soon for 6 months. Is this the best course of treatment? So worried it's spread

My husband had whipples procedure in Nov 25 he is still recovering from this. Had first oncology appt today we were told they had removed 9 lymph nodes 1 had cancer in it and could not take a complete margin ( can’t remember where she said because it was too close to a blood vessel ) to start a course of chemo cabetapine in a couple of weeks for 6 months - is the correct/ best treatment. So worried it has spread somewhere else ? Still coming to terms with the whole diagnosis