The stars have all criticised plans to close part of the Whittington Hospital and cut around 350 jobs so National Health Service (Nhs) managers can sell off a section of the building.
The Wire actor West has spoken out against the proposals, insisting the loss of the medical facility would be a "disaster" for locals.
He tells British newspaper the Camden New Journal, "Everybody should support this. It's essential this hospital stays open. There is a lot going on at the moment and not nearly enough is being done to stop it. We need to come together and do something now before it's too late, otherwise this will be a disaster. We will only know how bad it is when it's over, when this country is a very different place and all the damage has been done. They are trying to balance numbers but playing with lives. People think it's just one closure and they'll go elsewhere, but it is slipping from our grasp."
The Queen director Frears, whose brother was treated at the hospital after he suffered a heart attack, also issued a stark warning over the plans, adding, "I support the campaign to save the Whittington Hospital. My brother was in the hospital when he had a heart attack. Selling half of the Whittington would be a mistake... The money can be saved in other ways but it is not acceptable to close our hospital to cut costs."
Former Eurythmics star Lennox concludes: "The Nhs is a British institution, hospitals aren't a choice, they are a necessity. This is our country's backbone and it's slipping away."
Other stars to have backed the campaign to save the hospital include actress Juliet Stevenson, singer Alexandra Burke and theatre director Sir Richard Eyre, among others.
A demonstration will be held in north London on 16 March (13) to oppose the plans.