The study was conducted on mice, not men.
"The drugs prevented the transition of early cancer to a more aggressive and potentially fatal stage," says researcher Xi Zheng, MD, PhD, assistant research professor of chemical biology at Rutgers University in New Brunswick, N.J.
The results are so encouraging that a study of men with prostate cancer is already planned, he tells WebMD.
The findings were presented at the annual meeting of the American Association for Cancer Research (AACR).
AACR President Raymond Dubois, MD, a cancer specialist at the University of Texas M.D. Anderson Cancer Center in Houston, says the results are "very exciting," suggesting a new approach for preventing the progression of prostate cancer.
"This a kind of a dream team," he tells WebMD, referring to the fact that Lipitor and Celebrex are already taken by hundreds of thousands of people for high cholesterol and arthritis, respectively.
But, Dubois cautions, it's way too soon to recommend that people take these drugs for the purpose of controlling cancer.
Celebrex, Lipitor Inhibit Tumor Growth
Zheng says the new research built on earlier work showing that Celebrex and Lipitor both inhibit the growth of prostate cancer cells in tissue samples.
The new study involved mice with early prostate tumors that are dependent on male hormones called androgen to grow. At this stage, prostate cancer is highly curable.
The mice were deprived of androgen, and the tumors shrank.
Then the mice were divided into four groups: one got Celebrex, one got Lipitor, one got both drugs, and one got neither drug.
Tumors started to regrow in the mice that didn't get any drug treatment almost immediately. In contrast, all three drug approaches slowed the growth of new tumors.
The combination of Celebrex and Lipitor had the greatest effect -- and at lower doses than when administered separately.
"The combination had a bigger and safer effect than either drug alone," Zheng says. The ultimate goal, he says, will be to prevent early treatable androgen-dependent tumors from turning into more deadly androgen-dependent tumors.
"Once a cancer becomes dependent on androgen, treatment often becomes ineffective and the cancer cells become more aggressive," he says.