Unintentional Weight Loss Is 'Poorly Recognized' Among Doctors as a Symptom of Cancer

  • A new study found that unintentional weight loss (UWL) is a chronic illness symptom that often goes undetected in primary care offices.
  • While UWL is a recognized symptom, it rarely is prioritized amidst seemingly more serious conditions.
  • Experts recommend patients notify their primary care physician as soon as they notice UWL, so they can begin to understand what’s causing it.

New research found that unintentional weight loss (UWL), a common problem that frequently coincides with chronic illnesses like cancer, often goes undetected in primary care offices.

Undetected weight loss isn’t new, but its frequency and severity are growing concerns. A 2015 report found that only 40% of weight-loss cases, both voluntary and involuntary, were detected by primary care physicians.

Even when doctors do notice weight loss, there isn’t a standardized method for evaluating and diagnosing it. As a result, many cases of weight loss—some of which are related to cancer—are missed or misunderstood, contributing to delays in life-saving care.

“By detecting UWL early on, a patient with cancer is more likely to benefit from treatment, since the cancer is likelier to be in its early stages,” the study’s lead author Goutham Rao, MD, Jack Medalie Professor and Chairman of the Department of Family Medicine and Community Health at University Hospitals and Case Western Reserve University School of Medicine told Health

Woman talking to doctor

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Weight Loss as a Cancer Symptom

To gain a better understanding of UWL as a detected disease symptom, researchers from University Hospitals and Case Western Reserve University analyzed the electronic health records of 1.5 million adults collected between January 2020 and December 2021. They identified 29,494 patients who had two weight measurements recorded during the study period, and of those, 290 (1%) who experienced UWL. UWL was detected by physicians in only 60 patients (21%).

The researchers found that UWL was more likely to be identified in older patients, and among those who were diagnosed with UWL, the most common follow-up tests ordered were complete blood count, complete metabolic profile, and thyroid stimulating hormone level. Five patients were diagnosed with cancer within a year of experiencing UWL—the weight loss was recognized in three of the patients and undetected in two of them.

Dr. Rao noted there’s no single reason that UWL so frequently goes undetected, but rather a mix of factors that may cause the symptom to fly under the radar.

First and foremost, he explained that weight loss is often seen as a desirable health outcome for many Americans, even when people don’t intend to lose weight.

Wael Harb, MD, hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast Medical Center in Fountain Valley, CA, added that weight loss is often attributed to factors like stress, dietary changes, or other chronic illnesses. 

In addition, the electronic medical records (EMRs) that doctors use to store and track each patient’s medical history usually aren’t able to pick up on trends like weight loss and alert physicians of the changes. That onus falls on the doctor.

“Unless someone pays careful attention to weight changes, they are likely to go unnoticed,” Dr. Rao clarified. 

Finally, many people experiencing UWL are older Americans with co-morbidities, like diabetes, heart disease, and lung disease. Dr. Harb explained how weight loss is not deemed a top priority when patients have seemingly more serious conditions.

“I strongly believe weight changes often get ‘lost’ when physicians are dealing with so many other problems,” Dr. Rao agreed. 

All of these factors, combined with the fact that there’s no standardized guidance for evaluating UWL, enable ULW to go under-recognized.

Why Weight Loss and Cancer are Connected

Dr. Rao pointed out that cancer can cause weight loss through a few potential mechanisms. 

The first route is inflammation. When cancer is present, the immune system releases chemicals in the blood that can contribute to systemic inflammation, which can lead to muscle and fat losses.

Cancer can also affect people’s appetite and cause them to eat less food due to symptoms like pain or nausea, noted Dr. Harb. Cancer cells demand more energy, he added, which may cause the body to burn more calories than it normally would. Cancer can trigger metabolic changes, too, further fueling an unintentional loss of weight.

The big question that remains is: how much weight loss might indicate that someone has cancer? Current weight loss recommendations are based on opinions, not evidence, Dr. Harb explained. While there’s no universally accepted definition of UWL, doctors are currently advised to flag a patient’s health when they lose 5% of their weight in a period of 6–12 months.

“However, it’s important to remember that each case is unique, and other factors should also be considered,” added Dr. Harb.

Dr. Rao’s team is working to find this answer. “We are trying to identify records of a large number of patients to identify what threshold of weight loss is most useful to detect cancer,” he said.

Detecting Unintended Weight Loss Earlier

For now, researchers are still shaping the best practices that can hopefully be used for identifying UWL. Dr. Rao noted the first step is for patients experiencing UWL to alert their primary care physician.

If someone recently lost a notable amount of weight and is experiencing any other symptoms of cancer—change in bowel movements, abdominal pain, fever and night sweats, uterine bleeding, difficulty with urination—a physician’s evaluation is crucial. Based on their age, other signs and symptoms, and other risk factors, the physician may order laboratory tests, diagnostic imaging, or diagnostic procedures to determine what may be going on.

Even when weight loss isn’t a sign of cancer, it could still be a symptom of another chronic illness that requires treatment, such as diabetes, thyroid disease, and depression.

Early detection of UWL can help people address other factors that may be contributing to weight loss—such as nutritional deficiencies or mental health issues—improving patients’ overall well-being, added Dr. Harb.

Maintaining open communication with your doctor and promptly sharing any health changes can significantly improve your outcomes. “It often takes time to figure out the underlying cause,” concluded Dr. Rao. “But without knowing UWL has taken place, the underlying process may continue until the patient is very ill.”

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