Rational of using IOV

Dear colleagues, could someone give me an advice about the rational of using IOV in a particular circumstance? We have data from a clin trial with 3 occasions for each patient. It was a chemotherapy and the patients have received up to 7 cures. The issue is that the 3 occasions differ from one patient to another. Patient X may have be seen on cure 3, 5 and 7 while patient X+1 was seen on cure 2, 5 and 6 or whatever... It seems to me that combining the 1st occ of all patients is meaningless (as for 2nd and 3rd). Shall we use as many occasions as cures (7 in our dataset)? In that case, how many patients by occ is relevant as a minimum? For certain occ we may have few patients. Combining cures is hazardous and has no clinical justification. Best regards Nicolas Pr Nicolas SIMON Universite de la Mediterranee (Aix-Marseille II)