Despite the urging of nine persons, including two cancer patients, at a public hearing, Northern Virginia health planners have recommended denial of an application to open a radiation therapy unit in Prince William County.

The directors of the Health Systems Agency of Northern Virginia will consider the recommendation Monday. If they adopt it, it will be the first time a Washington area health planning group has denied a medical facility for one locality because it believes it more important to consider the overall needs of the Washington area.

The Northern Virginia health systems agency works with health planning agencies in the District of Columbia and Prince Georges and Montgomery Counties to try to eliminate duplication of services in the area. Proliferation of expensive medical facilities raises costs, which are reflected in higher medical insurance rates.

By a 4-to-2 vote, the Northern Virginia agency's project review committee recommended Wednesday night that the application for the radiation therapy unit in Prince William County be denied because there are more than enough such units in the metropolitan area already.

According to Dean Montgomery, executive director of the agency, the area has 21 radiation therapy units, although there will be a need for only 13 units by 1983.

"Were this to be adopted we would have a tremendous proliferation of these unnecessary services," said Irene Till, a committee member from Arlington who voted against the unit.

Another committee member who supports the unit, Helen Tobey of Prince William, said radiation therapy facilities are poorly distributed throughout Northern Virginia, thereby posing a hardship for Prince William County residents.

A middle-aged woman, who identified herself as Mrs. Patterson, said the two-hour trip to Fairfax for her radiation therapy is "very uncomfortable and inconvenient."

"How long do we have to drive north while our neighbors in upper Northern Virginia don't have to drive south to get these technical services?" Tobey asked.

Northern Virginia Radiology and Nuclear Medicine Inc. installed a rebuilt cobalt 60 radiation unit in a medical-dental building in Woodbridge last July at a cost of $116,451, according to the health planners.

However, the corporation never obtained a certificate of need from the state health commissioner, Montogomery said. Last month, the state health commissioner obtained a temporary injunction prohibiting the opening of the facility until it was approved by the state health planning and development agency.

An attorney for the firm said the radiation therapy unit in the county would draw 300 patients annually, but the health planners disagree. Montgomery estimates that about 100 patients would visit the unit.

All nine speakers at Wednesday night's hearing, including State Del. David Brickley (D-Prince William and Loudoun), two physicians, three group representatives, and a Catholic priest, said they favored the unit. No one spoke in opposition.

Voting against development of the unit along with Till were Edward Kelly of Arlington, Dorothy Mellor of Fairfax County and Dorothy Davies of Alexandria. Voting for the unit were Tobey and James Cantwell of Prince William.