6 years ago my partner Alison has had bowel cancer, followed a couple of years later by breast cancer. She has had operations for both, radiotherapy, chemotherapy, and anything else they could throw at her! She is in good health now, but has all sorts of scans, etc to check of any re-occurrence.
During her treatment, and since then, we have enjoyed many holidays abroad in Calis Beach and many other countries. With our insurance, we declare what she has had, which means that any condition requiring treatment directly relating to the cancer would not be covered whilst we are on holiday. It may sound extreme, but with cancer being a “slow burner” type of disease, it isn’t something that generally strikes you down instantly, like heart attacks, strokes, etc. We obviously didn’t travel whilst she was having some aspects of the treatment, i.e. chemotherapy, as that could have caused all sorts of other problems.
I do not know the condition of your partner, and our approach would not be for everyone. However, it is certainly something worth considering, and you partner can enjoy her trip whilst paying a “normal” tariff for her insurance. Most insurance companies will cover you, but it will probably need to be done by phone rather than online as its slightly different than normal. Our insurance is the travel insurance that comes with our Lloyds joint bank account, and they were certainly happy to do this at no extra cost.
Good luck whatever you decide to do, and I hope your partner has successful treatment, and subsequent recovery.