Sefton Central Labour MP Bill Esterson said he would challenge a decision to close the breast care service at Southport & Formby District General after the hospital announced this week that they were axing the service.
In a statement this week, Southport & Ormskirk NHS Trust executive medical director Rob Gillies said the breast care service was being closed due to "a national shortage of radiologists".
Mr Gillies said: "It is with great regret that, following discussions with our NHS commissioners, the Trust has taken the difficult decision to close its breast care service to new patients from September 1 2014.
"There is a national shortage of radiologists who specialise in this type of care and we have spent more than 12 months trying to recruit to a post caused by a staff member retiring. Arrangements to appoint a temporary radiologist fell through in early August.
"As it is not possible to run the service safely without a breast specialist radiologist in post, we have had no choice but to close the service to new patients.
"I can assure all existing patients due an investigation, treatment or follow-up that they will continue to be seen at Southport hospital with the support of visiting radiologists until the completion of their treatment.
"I will also be writing to reassure those patients that the quality and timeliness of their care will be unaffected by this decision.
"Our commissioners will be advising GPs about alternative services at neighbouring NHS trusts for new patients, so there should be no delay to them receiving investigation and treatment."
Bill Esteson MP said this will be a devastating blow to patients who rely on the hospital for breast screening and for treatment.
Bill said: "I am very concerned at this news. People want to go to their local services for such an important service. I have spoken to a number of people in Formby and Crosby who probably owe their lives to the fact that they were diagnosed early thanks to the excellent service available at Southport and Formby Hospital.
"I know from talking to constituents how much they value the support of the staff who run the service at Southport & Formby Hospital.
"The worry must be that this is a cut in the service and that the alternative care that will now be provided will see the quality of service fall. It’s all very well saying that existing patients will continue to be treated. Questions will need to be asked about whether the quality of care will be maintained for existing patients but what about new patients?
"I am determined to challenge this decision for the good of breast cancer patients and everyone battling this disease."
Bill has already contacted Southport & Ormskirk NHS Trust to raise concerns and written to Tory health secretary Jeremy Hunt about the issue.
Bill said: "If we don't have enough radiologists nationally, then the heath secretary is responsible. And is this is a national issue, then how many more hospitals are axing this vital service?
"Jeremy Hunt and his Tory-Lib Dem colleagues need to be held accountable for the disastrous policies they have implemented in government which are having such a devastating impact on our National Health Service. This looks like another cut in our NHS from the Tories and it is simply not acceptable.
"I will be raising this issue with Mr Hunt this week and I will be asking him and Southport & Ormskirk NHS Trust what provision is being made for patients who are diagnosed from now.
"I know people in my constituency and further afield will be gravely concerned about this issue and I will do all I can to get a local NHS service provided here for people in Sefton."