Obese patients being treated for breast or prostate cancer showed higher levels of mental and physical distress than nonobese patients, according to results from a retrospective study of more than 4,000 patients age 55 and older.
Investigators did not find the same correlation between obesity and distress in patients with colorectal cancer (CRC). Instead, those patients experienced “significant symptoms and distress” regardless of weight.
Lead study author Errol J. Philip, of the University of California, San Francisco, said the results do not suggest that obesity causes distress in patients with cancer. However, the findings showed a consistent association between excess weight and poorer psychosocial outcomes.
“In patients with breast cancer, obesity was associated with problems around sleep, fatigue, pain and physical functioning such as walking or climbing stairs,” he said in an interview. “We saw a similar pattern among the prostate cancer patients. They also reported high levels of fatigue as well as issues around sexual functioning.
“We can't make any causational arguments at this point, but we're able to identify a number of associations aligned with the broader literature that provide us with better insight into the experiences of patients as they move through treatment with and without excess weight.”
Results from previous studies in the general population have found an association between increasing body mass index (BMI) and greater pain, fatigue and sleep disorders. Furthermore, some reports have found that obese people are at higher risk for certain psychiatric illnesses, especially depression. Philip and his colleagues sought to determine if these observations held true in patients with cancer as well.
Investigators analyzed data from 4,159 patients who were treated at a large comprehensive cancer center in California from 2009 to 2017. Patients eligible for this study were 55 years or older and diagnosed with postmenopausal breast (52.2%), prostate (38.7%) or colon (9.1%) cancer.
Those with a body mass index (BMI) of 30 kg/m2 or more were classified as obese. Mean BMI was highest among patients with prostate cancer (28.6 kg/m2) compared with patients who had breast (28.1 kg/m2) or colon (26.9 kg/m2) cancer. However, more patients with breast disease (57.9%) were considered obese compared with those with prostate (53.9%) or colon (52.7%) cancer.
As a routine part of care, patients answered questions assessing their distress before starting treatment. They were asked to rank the levels to which they had experienced 33 problems on a five‐point scale from one (not a problem) to five (very severe problem). The questions focused on five domains: physical, practical, functional, emotional and other.
Investigators observed higher distress scores in obese versus nonobese patients in breast cancer (4.6 versus 4.0) and prostate cancer (3.13 versus 2.52). Obese patients in both cohorts also reported more physical, practical, functional and emotional problems.
In contrast, nonobese patients with CRC reported higher distress scores than obese patients (4.12 vs 3.56). Moreover, investigators did not observe a significant difference in physical, practical, functional, emotional or other problem scores between obese and nonobese patients.
The CRC cohort was much smaller than the other groups and Philip suggested that it might have been too small to generate an accurate picture of weight-based distress in these patients.
“Both groups (of CRC patients), regardless of weight status, tended to report fairly high levels of distress. It's possible that the nature of the disease and the sorts of side effects and symptoms that they experience washed out any effect of weight that we could have seen,” he added. “Other studies that have examined the same relationships among CRC patients, ones that have larger numbers of individuals involved, did see that sort of pattern between excess weight and greater symptom burden or greater distress.”
Philip noted that it is impossible for investigators in this study to know how much distress obese patients might have been experiencing prior to diagnosis. Obese people routinely face bias and shaming, so it is possible that these results are capturing elevated stress levels among this population in general, rather than something specific to obese patients being treated for cancer.
“We know that within the general populace, with or without cancer, there is a lot of discrimination and stigma surrounding (obesity),” Philip said. “That's definitely an element that plays into it.”
The U.S. Preventive Services Task Force issued nutrition and exercise recommendations for patients and survivors in 2012. These guidelines say that patients should be as active as possible. Furthermore, survivors are at increased risk for secondary cancers and chronic diseases including cardiovascular disease, diabetes and osteoporosis, and exercise is crucial tool for prevention.
Philip added that published reports show excess weight is associated with poorer outcomes for patients with cancer. The “million-dollar question,” he said, is: How does obesity affect patients as they move through treatment and post-treatment when it comes to symptom burden and engaging in health-promoting behavior?
“We're asking patients to move and eat better, but if you're dealing with a lot of side effects or a lot of distress, that can be difficult,” he said. “If they are experiencing greater symptom burden and poorer outcomes, it is incumbent upon (the medical community) to provide greater support and work out ways to promote health and well-being across that treatment and survivorship period.”