Overweight cancer patients may benefit from being tested for malnutrition, according to a new study.

Obesity increases the risk for cancer, so many patients are overweight or obese at diagnosis, and are typically not screened for malnutrition because they appear to be well-nourished, the authors write in the Annals of Oncology.

Obese cancer patients also tend to survive longer than underweight patients and that may further discourage nutritional screening, they add.

But recent studies have found that overweight people can also be undernourished, said lead author Dr. Ioannis Gioulbasanis of the chemotherapy department at Larissa General Clinic in Thessaly, Greece.

“However, it was the percentage of those patients found to be at nutritional risk that was surprisingly high in our study, around 50 percent, and that was at baseline, just after cancer diagnosis,” Gioulbasanis told Reuters Health by email.

He and his coauthors studied 1,469 patients with advanced cancer in France and Greece. Of those, 594 were overweight or obese.

With nutritional screenings and questionnaires, researchers determined whether the overweight and obese cancer patients were well nourished, “at risk,” or malnourished.

Screening included questions about weight loss, mobility, psychological stress, medical history, eating habits and how they viewed their own nutritional status.

Almost half the overweight and obese cancer patients were “at risk” for being malnourished and 12 percent were already malnourished, according to results.

Researchers followed the patients through chemotherapy treatment and measured the period between cancer diagnosis and death, which was available for 357 patients.

Well nourished patients survived an average of almost 18 months, compared to eight months for the “at risk” group and between six and seven months for the malnourished group.

Some overweight cancer patients who also have well-developed musculature will have a good prognosis, but those with excess fat and muscle loss, called ‘sarcopenia,’ generally have a very poor prognosis, Gioulbasanis said.

Most of the undernourished obese people in this study probably had sarcopenic obesity, he said.

“An obese or overweight patient who presents to a cancer center may have been 50 pounds heavier four months ago,” said Sarah Lowe, who researches nutrition and public health at the University of North Carolina, Chapel Hill.

“The fact that they are still overweight or obese may visually camouflage their compromised nutrition status, but they are still likely nutritionally depleted and at risk for continued significant weight loss.”

Malnutrition in cancer patients can increase the risk for infection, treatment toxicity and healthcare costs while decreasing treatment response, quality of life and life expectancy, she said.

“In my opinion, all cancer patients should ask to be referred to a dietitian,” Lowe said. “Many if not all treatments, whether it's surgery, chemotherapy, radiation, or chemoradiation can result in significant nutrition-related side effects that can have a huge impact (on) patients' quality of life and nutrition status.”

There are no specific guidelines or nutritional protocols designed for overweight cancer patients, Gioulbasanis said.

It is unclear whether obese cancer patients benefit from maintenance of their heavy body weight or whether some limited degree of weight loss could be in some way desirable, he said.

“In any case, adequate protein intake and preservation of muscle mass should be the target,” he added.

Gioulbasanis said overweight cancer patients should be included in nutritional screening, which is usually done by a nurse. Those who are malnourished should then be referred for a nutritional consultation.