A new specialist palliative care unit costing nearly £7m is being planned at the Royal Glamorgan Hospital near Llantrisant.
Charity Macmillan Cancer Support and Cwm Taf University Health Board have applied for planning permission to develop the £6.75m state-of-the-art unit.
If the plans are approved, Macmillan would contribute £5m towards the unit, making it their biggest single investment in Wales.
The specialist eight-bed unit would provide inpatient, outpatient and day palliative care and support for people with incurable cancer and other conditions.
Palliative care for cancer patients in the Rhondda is currently provided at Y Bwthyn Pontypridd Cottage Hospital.
It's location means that patients need to be transferred to Royal Glamorgan Hospital to access specialist tests and treatments, which can be difficult and distressing.
Similarly, some patients who go to Royal Glamorgan Hospital may benefit from being in a palliative care environment, but are too unwell to be transferred to Y Bwthyn.
If plans are approved, construction work would be expected to start later this year, with the centre projected to open in late 2018 or early 2019.