Sen. Orrin Hatch (R-Utah), a conservative, and Sen. Howard Metzenbaum (D-Ohio), a liberal, joined in a ripping bipartisan attack yesterday on the ability of Dr. Vincent DeVita Jr., a noted cancer therapist, to run the billion-dollar-a-year National Cancer Institute.

Backed by two other senators, Florida's Paula Hawkins and Oklahoma's Don Nickles, both Republicans, they voiced an almost unprecedently fierce assault on the head of a major unit of the respected National Institutes of Health as the Senate Labor and Human Resources Committee began hearings on the cancer institute's operations. Hatch, the committee chairman, acused DeVita of "gross mismanagement."

Their general complaint is that the cancer institute -- and DeVita -- coddle rather than punish scientific wrongdoers and spend money too freely without firm controls. Yesterday's harsh rhetoric was the opening salvo that could signal an end of the historical honeymoon between Congress and the cancer researchers.

One major specific issue was a large and coveted $910,000 NCI research grant to Dr. Marc Straus of New York Medical Colege. The grant was made in April 1980, only months after Straus was forced to resign from Boston University following accusations of grossly falsifying results of experimental cancer treatment to make his project look good.

There are allegations that the newly powerful Sen. Hatch Believes President Reagan should replace DeVita as cancer institute director. Hatch yesterday went a long way toward confirming this.

"You have not done the job I feel you should have done," he told DeVita. And: "You don't know how important it is to manage."

Metzenbaum chimed in. In giving money to Straus, he told DeVita, "I think you are putting yourself in a position to be fooled twice with government money."

"I have a lot of respect for you as a professional," Metzenbaum added. An administrator also has to have "some dynamics," he said, and "it seems to me the dynamics are totally absent . . . Dr. Straus doesn't bother me as much as you do."

Chairman Hatch and former chairman Edward M. Kennedy (D-Mass.) locked horns over Hatch's management of the committee, as Hatch ignored the Senate's 10-minute rule, under which each senator in turn takes 10 minutes for questioning in committee hearings. Hatch opened by grilling DeVita for 45 minutes.

Hatch promised to give every senator plenty of time but told Kennedy: "Let me do it this way, and frankly I'm going to do it this way."

DeVita defended himself on the Straus matter, saying he thought Straus should be regarded as innocent of falsifying data until proved guilty; the matter is still under investigation. He said NCI quickly cut Straus off from any participation in patient care, though for a time Straus was a "secondary investigator" on another scientist's project, without top NCI officials' knowledge. He said Straus's new project involves only laboratory and animal research, not patients.

Domuments submitted to the committee accuse Straus of giving some patients radioactive injections without their consent, and in some case altering blood counts and omitting previous cancer treatments.

Also, DeVita said, in 1979, when he was NCI clinical (or treatment) director, and in 1980 when he became director, NCI did not have the "procedures" to deny a scientist a grant when there were only unproved accusations. "We have the mechanisms now," he said And he described many other management changes intended to satisfy government auditors' complaints about NCI management.

But he also conceded as the hearing proceeded -- and Hatch and his colleagues pressed in -- that, given hindsight, he would have acted differently on Straus and not given him a new grant at all.

DeVita even promised Nickles that he would consult his legal counsel and his presidentially appointed National Cancer Advisory Board about canceling or delaying the remaining two-year share of Straus' three-year grant.