Can Anointing of the Sick be repeated?

Yes. The Catechism addresses repetition directly: "If a sick person who received this anointing recovers his health, he can in the case of another grave illness receive this sacrament again. If during the same illness the person's condition becomes more serious, the sacrament may be repeated."

This surprises many people, who treat the sacrament as something to be saved for the right moment. Cancer is often a long illness with several turning points, and the sacrament is not a single allocation to be spent carefully.

The same passage adds that it is fitting to receive it just before a serious operation, and that the same applies to elderly people whose frailty becomes more pronounced.

In practice, people with cancer commonly receive it before major surgery or a transplant, again if the disease recurs, and again if the situation deteriorates. Asking a second or third time is not unusual and no priest will find it strange.

Whether the timing is right for your situation is something a priest or hospital chaplain can help you think about. Your care team can tell you what is happening medically, which is often the information that makes the decision clearer.