I cannot recall if you and your sister are Jewish... If so you might provide us with her Hebrew name...
ie. Rachel Bat Sarah (Rachel daughter of Sarah).... We use the Hebrew name when praying for Refuah Shlema (complete healing)...
If we don't know her Hebrew name we use her secular name, ie. Tracy Bat Sarah...
May she be granted a complete healing from this sickness...
My step-father just started his chemo for a case of cancer he has been fighting for almost 10 years