Adjuvant Chemotherapy Modestly Improves Survival in Some Men with Prostate Cancer
June 8, 2015, by NCI Staff
Giving some men with prostate cancer chemotherapy after standard treatment with radiation and hormone therapy modestly improves how long they live, according to results from an NCI-funded clinical trial. Results from the trial were presented at the American Society of Clinical Oncology annual meeting in Chicago.
Among the most common cancers, prostate cancer is the only one in which adjuvant chemotherapy—which is given after the completion of primary treatment and is intended to prevent cancer from returning and extend survival—is not routinely used.
The findings presented at the ASCO meeting are the first to show that adjuvant chemotherapy can extend survival in men with prostate cancer, explained the study’s lead investigator, Howard Sandler, M.D., of Cedars-Sinai Medical Center in Los Angeles.
Each year, more than 30,000 men are diagnosed with high-risk, localized prostate cancer. The standard treatment for these men is radiation to the prostate, followed by 2 to 3 years of therapy with drugs that block the hormones that prostate tumors rely on to grow and spread.
In the trial, 563 men with prostate cancer that had not spread beyond the prostate but was considered to be at high risk of returning were randomly assigned to receive six cycles of the chemotherapy drug docetaxel after they finished standard treatment or just standard treatment. The median follow-up in the trial was 5.5 years.
More than half of the men in the trial had prostate cancer with features that put them at particularly high risk of recurrence, Dr. Sandler said.
Ninety-three percent of men in the adjuvant chemotherapy group were still alive 4 years after starting treatment, compared with 89 percent of men treated with radiation and hormone therapy alone. Men who received adjuvant chemotherapy also had a lower risk of developing distant metastases, which Dr. Sandler called a “highly clinically important finding” because distant metastases are associated with increased mortality.
Although the survival improvement was small, the fact that adjuvant docetaxel improved overall survival in such a short period “is quite a significant outcome,” said Charles Ryan, M.D., head of the Genitourinary Medical Oncology Program at the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center.
The trial results “have the potential to impact practice patterns,” said William Dahut, M.D., of the Genitourinary Malignancies Branch in NCI’s Center for Cancer Research. In men with early metastatic prostate cancer, treatment with docetaxel improves survival, Dr. Dahut continued, “so this seems like a logical extension of that.”
In clinical practice, he noted that the patients most likely to receive adjuvant docetaxel may be healthier or younger (those who have a longer overall life expectancy) and patients who have the highest volume or most aggressive disease. “Some other patients may decide against it because of the potential risk of side effects, because the absolute benefit so far is relatively small,” he said.
Dr. Sandler agreed, saying patients with the most aggressive cancers would be the best candidates for adjuvant docetaxel. “In intermediate, lower-risk subsets [of patients], I would not recommend it.”
Longer follow-up of the men in the trial is planned, Dr. Sandler noted.