CHICAGO (CNNMoney.com) -- Tests of alternative cancer treatments show that ginseng and flaxseed could benefit patients while shark cartilage may not be an effective treatment, according to study results released Saturday.
Early-stage studies have shown that the herb ginseng could reduce fatigue, a common cancer symptom, according to findings released at the annual conference of the American Society of Clinical Oncology.
The first human study on ginseng and cancer involved 282 patients who took the Wisconsin-grown herb over an eight-week period. Among patients taking the larger 1,000 mg or 2,000 mg daily doses, 25 to 27 percent said their fatigue levels had improved, compared to 10 percent for those taking 750 mg or placebo.
"While the results of this study are very promising, further studies are needed to determine the definite benefit, and we cannot recommend routine use of ginseng for fatigue in cancer patients at this time," said Dr. Debra Barton, leader of the study and oncology professor at the Mayo Clinic, in a prepared statement.
"Because this was a pilot study," Barton continued, "we cannot be certain that ginseng really works to decrease fatigue, and if it does, what dose works best."
A later-stage study (known as phase 2) of 161 prostate cancer patients showed that flaxseed slowed the spread of cancer by 30 to 40 percent. But the study also determined that reducing fat intake in a patient's diet had no noticeable impact on cancer.
The leader of the study, Dr. Wendy Denmark-Wahnefried, a professor of nursing and surgery at Duke University Medical Center, said that "flaxseed may well protect against prostate cancer growth," but further studies were needed.
A late-stage study that added the use of shark cartilage to chemotherapy showed that it had no effect as a lung cancer treatment, according to study leader Dr. Charles Lu, associate oncology professor at the University of Texas.
Shark cartilage has been marketed as a cure that blocks blood vessels that feed tumors, according to the study. 
