Prostate Cancer Radiation: Is High Dose Better?

Sept. 13, 2005 -- Increasing the dose of radiation therapy may lower the chances of prostate cancer's return.

Radiation therapy is an effective treatment for prostate cancer. But researchers have been looking for ways to further lower the chance of the cancer coming back.

The study appears in The Journal of the American Medical Association.

The researchers included Anthony Zietman, MD. He works in the radiation oncology department of Massachusetts General Hospital and Harvard Medical School in Boston.

PSA Indicates Cancer Recurrence

Zietman and colleagues studied nearly 400 men with cancer that hadn't spread beyond the prostate. All had blood PSA levels less than 15 ng/mL.

The men either got normal or higher radiation doses to treat their cancer. About five years later, fewer men in the high-dose group had increasing PSA levels. Increasing PSA levels indicate that prostate cancer has come back.

PSA is made by the prostate gland. High PSA levels may indicate prostate cancer or noncancerous conditions such as prostatitis or an enlarged prostate.

Higher Dose Helps Keep Cancer Away

Five years after high-dose treatment 20% of men had PSA levels that indicated cancer recurrence compared with 38% of men that received the traditional radiation dose.

There was "only a small increase" in urinary or rectal problems with the high radiation doses, write the researchers.

Time's Influence

Prostate cancer can span decades, so the study's follow-up time might be considered short, the researchers note.

The gap between the treatment groups might narrow over time, but no one knows yet if that will happen.

"If this proves to be the case, then it would seem that higher doses of radiation delay, rather than prevent, recurrence," write Zietman and colleagues.

Second Opinion

An editorial in the journal offers another perspective.

The editorial was written by Theodore DeWeese, MD, and Danny Song, MD. They work at the department of radiation oncology and molecular radiation sciences at Johns Hopkins University's medical school.

DeWeese and Song -- who didn't work on the study -- raise several questions. Would even higher radiation doses be more helpful? Does high-dose radiation improve survival? What's the best way to raise radiation doses?

Still, they write that the findings "support the use of higher radiation doses in men with lower-risk prostate cancer" and "will serve as an important foundation for future work."

About Prostate Cancer

More than 232,000 new cases of prostate cancer will be diagnosed in the U.S. in 2005, predicts the American Cancer Society (ACS).

Prostate cancer is the No. 2 cause of men's cancer deaths, though the prostate cancer death rate is dropping, says the ACS.

Prostate cancer is most common among older men. About two out of three cases are found in men older than 65. Prostate cancer is also more common -- and more deadly -- among black men than whites, according to the ACS.

Preventing Prostate Cancer

Prostate cancer's exact cause isn't known, so it's not currently possible to prevent most cases of the disease, says the ACS.

A healthy lifestyle may help.

The ACS recommends eating at least five daily servings of fruits and vegetables. Consider putting cooked tomatoes on the menu (think tomato sauce or tomato paste), since they're rich in cancer-fighting lycopene. Pink grapefruit and watermelon also contain lycopene.