Researchers analysed the diets of about 1,500 cancer survivors and 3,000 people without any history of tumours, ranking them based on how well they followed U.S. dietary recommendations.
Neither group ate very well, but the cancer survivors generally had less nutritious habits than the other people in the study, researchers report in the journal Cancer.
Read: Cancer and diet
The findings are troubling because nutrition plays an important role in preventing diseases, and poor eating habits can exacerbate many chronic health conditions common among cancer survivors, lead study author Dr Fang Fang Zhang, a nutrition researcher at Tufts University in Boston, said by email.
Quality of life
"It is remarkable that cancer survivors are still burdened by suboptimal dietary intake," Zhang said. "Not getting enough fiber and having too many empty calories are established risk factors for many chronic health conditions."
As advancements in screening and treatment have helped make cancer less fatal, doctors and scientists have increasingly turned their attention to quality of life for survivors, Zhang and colleagues note.
Cancer survivors can face increased risks of serious complications and premature death from chronic health problems like cardiovascular disease and diabetes, previous research has found.
Data for the current study came from adults who participated in U.S. dietary surveys between 1999 and 2010 and reported how often they consumed recommended amounts of foods like fruits, vegetables, greens and beans, whole grains, dairy, seafood and plant proteins and fatty acids.
Researchers also examined how much people ate refined grains, salt and empty calories.
Then, they ranked the diets, awarding a perfect score of 100 to diets that included all recommended servings of recommended foods without adding non-nutritious items to the mix.
Cancer survivors scored a 47.2 on average, while the other people did slightly better with a typical score of 48.3.
The people who survived cancer tended to get more points deducted for empty calories, solid fats, sugary foods, and alcohol than others in the study. Cancer survivors also ate fewer vegetables.
Unfortunately, the researchers admit, they didn't know the timing of the cancer diagnoses or the treatments patients received. It's also impossible to tell from the study whether cancer survivors' diets were different before their diagnosis.
For at least some cancer survivors, dietary habits can be shaped by the lingering effects of their treatment or the tumours they endured, noted Samantha Heller, a nutritionist at New York University Langone Medical Centre who wasn't involved in the study.
Survivors may be dealing with altered taste, decreased appetite and fatigue which can all contribute to a lack of ability or interest needed to prepare and eat healthy meals, Heller said by email.
Some cancer survivors also suffer from weight loss and are encouraged to eat whatever high calorie and high protein foods they want, she noted.
"While there is no way to know the lifestyle of all cancer patients, it is a safe bet to say that at this point the evidence points to a diet of primarily whole grains, legumes, vegetables, fruits, nuts and seeds, consuming little or no alcohol, regular exercise and not smoking tobacco as ways to help reduce cancer risk," Heller said