Many of the doctors and nurses treating cancer patients underestimate how often their patients become nauseated and vomit in the days after chemotherapy, according to a new study. Researchers from the US and Europe say that clinicians need to recognize this problem in order to better control it.

"Effective treatment for a problem cannot be administered unless caregivers realize that the problem exists," wrote lead author Steven Grunberg, MD, of the University of Vermont. "Nausea and [vomiting], particularly delayed nausea and [vomiting], continue to be significant problems for patients with cancer receiving chemotherapy."

In the past, researchers have found that nausea and vomiting were the side effects most feared by patients who were receiving chemotherapy.

Cancer physicians and nurses routinely give their patients drugs to prevent nausea and vomiting immediately after chemotherapy, and the treatment is usually quite effective. The problem, say the researchers, is that the clinicians aren't paying enough attention to the nausea and vomiting that occur over the next few days, when the patient is at home and the drugs given in the office are no longer effective.

Grunberg and his colleagues studied patients and their caregivers in 14 oncology practices in Denmark, France, Italy, Germany, the UK, and the US. The 24 physicians and nurses were asked to estimate the amount of nausea and vomiting their patients experienced 24 hours after receiving chemotherapy and over the next 5 days. The 298 patients were asked to keep a diary of how much nausea and vomiting they experienced in the days after receiving chemotherapy.

The clinicians accurately predicted the frequency of this side effect immediately after chemotherapy, but more than 75% of them underestimated the amount of later nausea and vomiting. They thought that about 20%-40% of their patients would develop nausea in the days after chemotherapy and that around 15%- 25% would have vomiting. The estimates varied depending on how likely it was that the chemotherapy they were giving would cause nausea and vomiting.

But the patients reported that they actually had nausea about 50%-60% of the time in the days after receiving chemotherapy, and vomiting about 28%-50% of the time.

Grunberg called this discrepancy the "most striking finding" of the study.

"Though physicians and nurses have an absolutely accurate sense of acute chemotherapy-induced nausea and vomiting, they need to expect and more adequately treat delayed nausea and vomiting in chemotherapy patients," he said in a statement.

Grunberg points out that there are new anti-nausea drugs that are longer-lasting and some that work better on the delayed nausea and vomiting. Physicians and nurses, he says, need develop a way of learning if their patients are having these problems at home.

The study was funded by Merck & Co., which manufactures a drug recently approved for treating delayed nausea and vomiting caused by chemotherapy. Several of the study authors are Merck employees, and Grunberg is a consultant to the company.

The study appears in the online edition of the journal Cancer and will be published in the May 15 print edition.