Washington ? It’s a worrisome finding: About a third of patients with potentially curable breast cancer aren’t getting full-strength doses of chemotherapy because of side effects or other problems.

Now researchers are preparing to find out whether this inadvertent chemo-lite is common with other cancers, too — and how much the dose can dip before patients’ chances of survival are harmed.

“This is not just a breast cancer problem,” predicts Dr. Gary Lyman of the University of Rochester Medical Center, who is leading some of the research.

“We’re very concerned about it,” adds Dr. Larry Norton, deputy physician-in-chief for breast cancer at Memorial Sloan-Kettering Cancer Center.

Norton’s research shows that undergoing breast cancer chemotherapy every two weeks instead of every three can improve survival by 30 percent. That means skipping chemo sessions or lowering doses has ominous implications.

Strict scientific studies set the “dose intensity” for different chemotherapy cocktails — the proper dose plus how often it must be given.

But community oncologists often don’t stick to those recommendations as rigorously as do researchers, and Lyman’s breast cancer data provides the best picture of that so far. He reviewed medical records for more than 20,000 breast cancer patients who underwent postsurgery chemotherapy.

Lyman found that more than half received less than 85 percent of the recommended dose intensity that is considered the minimum for optimal treatment. For a quarter of patients, the problem was postponing chemo sessions; for the rest, it was dosage cuts, presumably because of side effects.