Researchers at Roswell Park Comprehensive Cancer Center are shedding light on how Body Mass Index (BMI) impacts treatment response, risk of recurrence and survival in patients with head and neck cancer.
Their retrospective study, published late June in JAMA Network Open, found that head and neck cancer patients with an overweight BMI had better outcomes than those with a normal or obese BMI, including longer overall and progression-free survival and lower rates of locoregional failure — persistent or recurrent disease around the tumour site and in nearby lymph nodes.
Sung Jun Ma, MD, former Department of Radiation Medicine resident at Roswell Park, is first author of the study.
BMI is a score calculated by taking a person’s weight and dividing it by the square of their height.
Scores fall into four categories: underweight, for a BMI less than 18.5; normal weight, between 18.5-24.9; overweight, between 25-29.9; and obese, 30 or higher.
Both overweight and obesity are associated with high blood pressure, type 2 diabetes, coronary heart disease, stroke and increased risk of several types of cancer — and it’s estimated that by 2030, nearly half of all adults in the US will fall into the obese range.
Growing rates of overweight and obesity call for a better understanding of how excess weight impacts both cancer risk and treatment outcomes.
Previous meta-analysis and prospective studies involving cancer patients have linked excess weight to increased risk of death, both from cancer or any other cause.
But there are exceptions: research shows that obese patients with lung cancer or renal cell carcinoma tend to fare better than non-obese patients.
The effects of overweight and obesity on head and neck cancer have been less clear, especially in patients who receive a combination treatment, such as chemotherapy plus radiation, called chemoradiotherapy.
Those patients often develop significant medical problems as a result of therapy, including weight loss and loss of muscle, which are associated with poor prognosis.
How does BMI affect their treatment outcomes?
To learn more, the investigators analysed data from 445 patients with non-metastatic head and neck cancer who were treated with chemoradiotherapy at Roswell Park between Jan 1, 2005, and Jan 31, 2021, including 107 with normal BMI, 179 with overweight BMI and 159 with obese BMI.
The team focused on comparing overall survival and progression-free survival among the three groups.
Because too few eligible patients had an underweight BMI, that group was excluded from the study, as were patients who were treated with surgery or radiation therapy alone.
Treatment was interrupted for only three patients.
PET-CT imaging after treatment revealed that complete metabolic response — no evidence of cancer — was higher in patients with overweight BMI (91.6%) versus those with normal BMI (73.8%) and higher in patients with obese BMI (90.6%) versus those with normal BMI (73.8%).
However, only overweight BMI was linked to improved five-year overall survival, at 71.5% versus 58.4% for normal BMI; five-year progression-free survival, at 68.3% versus 50.8% for normal BMI; and lower locoregional failure, at 7.0% versus 25.9% for normal BMI.
“In other tumour types, obesity has been shown to be a negative factor, but in head and neck cancer patients, being overweight improved survival,” says Anurag Singh, MD, Director of Radiation Research, Director of Head and Neck and Lymphoma Radiation Services and Co-Leader of the Cancer Stress Biology Program at Roswell Park, and principal investigator of the study.
The authors note that further work is needed to clarify how BMI affects patients with head and neck cancer.
“There is a complex interaction between cancer and the patient’s weight, nutritional status and muscle mass,” notes Dr Ma.
“For some reason, the same cancer in patients with normal BMI may behave more aggressively than in patients with overweight BMI, even if they receive the same treatments. Those with normal BMI may need more-intensive interventions to improve their outcomes.”
The researchers believe this is the largest study of its kind involving patients in the US and the first to show that overweight and obese BMI are associated with complete metabolic response after treatment.