Unintentional weight loss can present diagnostic challenges, according to researchers from University of Barcelona. So many factors are involved, and so many causes are possible, extensive and invasive investigation often is needed. And because cancer may be the underlying cause of weight loss in patients with few or no symptoms, a swift workup is crucial. Most studies of unintentional weight loss (UWL) have been limited by small sample sizes, short or variable follow-up, or focus on older patients, the researchers say. So they conducted the largest and longest prospective study thus far, following 2,677 patients for > 5 years.
The patients were referred to an outpatient diagnosis unit for evaluation of UWL as a dominant or isolated feature of disease and underwent a standard baseline evaluation with laboratory tests and chest X-ray. Those without identifiable causes 6 months after presentation were followed for 60 more months. Older patients also were given an oral cavity examination, a videofluoroscopy or swallowing study, and a depression and cognitive assessment.
At 6 months, 582 patients had unexplained UWL. Of those, 27 had malignancies: 11 patients had pancreatic cancer; nine had lymphoma. Nearly half of the cancers were digestive; of those, pancreatic cancer accounted for 19%, followed by lung (17%); lymphoma (11%); and kidney, ureteral, and bladder cancers (10%). Of 450 nonmalignant organic disorders, 45% were digestive.
Cancer patients had the highest mortality rate (69% vs 5%-6% in other groups). Decreasing weight was substantially more common in survivors with malignancies (66%) than in the rest of the patients studied, as well as in survivors with nonmalignant organic disorders (10%) than in unexplained UWL and psychosocial disorders. Patients with cancers were older, male, and active smokers, with a greater weight loss than patients in other groups. They also were more likely to have accompanying symptoms and abnormalities on physical examination, lab tests, and chest X-ray.
Cancer evading early diagnosis is a major concern, the researchers say. One of the main findings of the study was the long follow-up of patients with unexplained UWL: a mean of 47.5 months. Based on their findings, occult malignancies detected during a follow-up of up to 66 months after presentation “do not seem to be as rare as thought.” Moreover, autopsies of 13 patients showed malignancies in eight.
However, the fact that only 1 in 20 patients received a cancer diagnosis within that period—most notably within the first 28 months after referral for workup—is “fairly reassuring.” However, they recommend continuing to regularly evaluate patients with UWL for longer periods even if they had a normal evaluation and workup.