Fish oil may help stabilize cachetic cancer patients

Gastrointestinal side effects make high-dose fish oil capsules difficult for many people with cancer-related cachexia to tolerate, but patients who are able to take the supplements regularly may be able to stabilize their weight or even gain pounds, according to a report in the July 15th issue of Cancer.

Animal studies and some clinical investigations have suggested omega-3 fatty acids may protect against cachexia, Dr. C. Patrick Burns of the University of Iowa in Iowa City and colleagues note.In the current phase II study, 43 patients with moderate to severe malnutrition were prescribed 0.15 g/kg day of eicosapentaenoic acid plus docosahexaenoic acid. One capsule was taken with breakfast and one with lunch. The researchers began the study with a 0.3 g/kg day dose, but halved it because many patients were unwilling or unable to take so many capsules.Among the 36 patients who took at least one capsule and did not have edema, 12 patients gained weight and 22 lost weight. Six patients were able to gain more than 5% of their body weight or achieve their normal weight, and 24 more stabilized their weight, meaning they gained or lost no more than 5%. Six more patients lost more than 5% of their body weight.Gastrointestinal side effects were common, and included nausea, emesis and diarrhea, and the size of the capsules made them difficult for some patients to ingest. Nineteen patients stopped treatment early due to side effects. There was a wide variation in capsule tolerability among patients, the researchers note. Some reported few or no gastrointestinal side effects. “It did not seem that gender, age, or ethnicity predicted intolerance, but the study was not powered to test that question,” Dr. Burns told Reuters Health.While the median weight loss was 0.8 kg, the researchers note, patients were losing an average of 4% of their body weight per month at the study’s outset, and the median loss for the entire group during the study was 1.2% per month, less than would have been expected.There are three mechanisms by which omega-3s may have this effect, dr. Burns noted in an interview with Reuters Health. Omega-3s, in particular eicosapentaenoic acid, inhibit secretion of pro-inflammatory cytokines. Tumors may promote cachexia by releasing factors that stimulate production of these cytokines, he explained, so the fatty acids would block this process. Also, he added, omega-3 fatty acids may inhibit protein degradation by blocking proteasome activity, and may also slow fat breakdown.Future studies of fish oil for cachexia that begin when patients are less severely ill, and last for longer than 30 days, may have more positive results, the researchers suggest.The supplements could also be combined with megace or other agents now under investigation for treating cancer cachexia, such as olanzapine or proteasome inhibitors including bortezomib, Dr. Burns added.(Source: Cancer 2004;101:370-378: Reuters Health News: Anne Harding: Oncolink: August 2004)