Uncaused significant weight loss predicted cancer diagnosis within a year
American scientists analyzed data from nearly 160,000 people and found that an unwarranted history of weight loss of more than ten percent was associated with a significant increase in the risk of being diagnosed with cancer within 12 months. As reported in The Journal of the American Medical Association, this association remains significant in the two years following the first report of weight loss.
Although weight loss is a well-known symptom of cancer, physicians do not know exactly over what period of time or how much weight a patient must lose to be considered cancer alert. Previous studies of the association between weight loss and risk of tumor diagnosis lacked data on weight loss trends and control group. In addition, virtually no one had assessed the absolute risk of cancer associated with a given weight loss.
Therefore, a team of scientists led by Brian Wolpin of Harvard Medical School examined registry data from nurses and health care workers to identify associations of recent weight loss with subsequent cancer risk and with specific cancer types. The study sample included 157474 individuals aged 40 years and older (mean age 62 years). During 1.64 million person-years of follow-up, there were 15809 cases of cancer with an incidence rate of 964 cases per 100000 person-years. The mean follow-up period was 28 years. Participants with any weight loss had similar sex, race, body mass index, and lifestyle factors compared with those without weight loss.
Among participants who were diagnosed with a neoplasm within one year of the weight assessment, 15 percent had a weight loss of more than five percent of their body weight and five percent had a weight loss of more than ten percent. The incidence rate of malignancy was 1,362 cases per 100,000 person-years among participants with recent weight loss of more than ten percent versus 869 cases per 100,000 person-years among participants without recent weight loss; the difference between groups was 493 cases per 100,000 person-years (p < 0.001).
The most common types of neoplasms among participants with recent weight loss were tumors of the upper gastrointestinal tract, as well as liver, biliary tract, and pancreas. The risk of cancer diagnosis was higher during the first 12 months compared to the period between 13 and 24 months after weight loss was reported.
The results of this study stratify the risk of malignancy according to the degree of recent weight loss. This will help primary care physicians to be more alert to cancer depending on the history of weight loss.