John Larpenter, a cancer patient, phoned me in anguish one day last month.

He was on a cancer ward at the Washington Hospital Center, and he was choking, he said, on the cigarette smoke of his roommate.

His roommate was being treated for lung cancer.

"Don't Washington hospitals have any policy about this?" Larpenter asked. "Don't they have a policy on the oncology cancer wards -- not to put you in a room with someone smoking?"

Larpenter -- not his real name; "please leave my name out," he said -- spoke in a weak and tired voice. He was on his third day of chemotherapy for an advanced lymphoma, a cancer of the lymphatic system.

"I smelled smoke all day yesterday," he said. "Then I noticed that the other man in my room was smoking. I don't think he can get along without it.

"Last night the smoke woke me in the middle of the night, and I started coughing. They tell me one of the chemicals I'm getting can sometimes cause lung reactions, so the smoke concerns me. I've been asking since yesterday for a private room."

At the time he called he had not been offered one. "Don't you think this is wrong?" he asked. "Don't you think the government should have some regulations about this?"

The rest of Mr. Larpenter's story is unclear. According to Stephanie McNeill, the hospital's public affairs director, the nurses too smelled smoke coming from Larpenter's room but could never catch his roommate smoking, and that patient denied smoking. Just the same, McNeill said, Larpenter was finally offered a private room and refused.

Did Larpenter lose his resolve? Did his roommate stop smoking? I couldn't find out. Larpenter has been too ill to respond.

But the question remains: How hard should a patient have to work to be free from a roommate's cigarette smoke?

"The Washington Hospital Center's policy is very definite," McNeill said. "We try not to say to any patient, 'You must' or 'You must not.' But our patient handbook reads: 'For the sake of your health and that of other patients, we urge you not to smoke during your stay. Patients who wish to smoke must have permission from their physicians. If you plan to smoke and your roommate objects, you will be transferred to another semiprivate room whose occupant does not object, or if such a room is not available, to a private room at your expense . . .' "

"Sometimes it's easier to move the nonsmoker," McNeill said. "Then we pay the difference," only $10 a day at this hospital. "The difficulty when that patient first complained was that those units were very full. Sometimes moving one patient can mean moving whole groups of people. But we make every effort to get every person an acceptable roommate."

Some hospitals, Sibley for example, now permit smoking only in smoking lounges and permit no smoking at all in patient rooms. As a precaution against fire, some hospitals permit smoking only when a nurse or visitor is present. Alexandria Hospital has been phasing in progressively stricter rules and plans to make the hospital entirely smoke-free by 1989.

Patient Larpenter reported still another problem with his roommate when he phoned last month.

"He has the television on 24 hours," Larpenter said. "All private eyes and rock music. I take a pill to try to sleep, and, with the TV on, I still can't sleep.

"I finally raised the roof last night, so at 3:30 in the morning -- since my roommate was sleeping -- they finally turned it off."

There is a hospital policy here too, McNeill reported. TV and lights are supposed to be out at 10 p.m. in semiprivate rooms. If Larpenter's roommate's TV was on later, that was in violation of hospital policy. The nurses' notes, said McNeill, do show that the nurses asked him to turn off the TV.

"The problem," she added, "is that when you have two sick people in a room, what's going to help one could be counter-productive for the other. Some people want quiet. For some, sick and anxious, it helps to watch Johnny Carson.

"We and other hospitals are trying to convert as many rooms as we can to private rooms for this and other reasons."

If you have to be hospitalized:

*Consider asking for a private room if you can afford it and you prefer quiet and solitude to company that can include all your roommate's visitors.

*If you're to be in a semiprivate room -- the euphemism for a room for two -- speak up in advance if you want to be with a nonsmoker, or if you want to smoke and the hospital allows it. Better yet, phone the hospital as many days as possible in advance.

*If you wind up in the wrong kind of room, keep complaining, and ask your doctor to help you.

Next Week: A hospital tries hospitality.