To palliate is to alleviate a symptom without curing the underlying medical condition.
The term is used widely in health care to refer to treatments or interventions (including surgical) that are focused on alleviation of pain or other symptoms; it and is not necessarily limited to care provided for eventually fatal conditions.

Palliation in relation to end-of-life care is the relief of symptoms and suffering caused by cancer and other eventually fatal conditions.
Palliation helps a patient feel more comfortable and improves quality of life but does not cure the disease.
Palliation of symptoms is a key goal of care for both end-of-life and palliative care.

Palliative Care Australia. Palliative and end-of-life care glossary of terms. 2009.