Hope for a better prostate cancer test, potential new uses for a largely discredited lung cancer drug and a warning for breast cancer patients all emerged from a meeting earlier this month of the American Society of Clinical Oncology in Orlando.

Prostate cancer is the most common form of cancer in American men, with an estimated 186,320 cases diagnosed in 2008. But every year, at least that many men undergo painful and expensive prostate biopsies after routine screening has revealed high levels of prostate-specific antigen, or PSA, and yet the men turn out to not have tumors.

Many critics have charged that the large number of unnecessary biopsies grossly limits the benefits of the PSA test and have called for a halt to its use.

An experimental blood test that looks at the activity of six genes linked to prostate tumors could improve the accuracy of PSA testing greatly and, said Dr. Robert W. Ross, ``could spare tens of thousands of men from undergoing prostate biopsy each year if validated in further studies.''

Ross, of Harvard Medical School's Dana-Farber Cancer Institute in Boston, was speaking to researchers.

Together, the two tests detect cancer accurately more than 90 percent of the time, compared with only about 60 percent to 70 percent for the PSA test alone, Ross said. Widespread use could spare men anxiety and needless testing, he said, and could save the U.S. health-care system more than $2 billion per year.

Ross and Dr. William K. Oh of Dana-Farber worked with researchers at Source MDx in Boulder, Colo., to develop the test, which examines signs of tumor gene activity (RNA) in the blood.

The team examined 174 genes associated with inflammation and cancer, studying 76 men with known prostate tumors and 76 healthy men. They found that six genes were closely associated with the presence of a tumor. RNA from five of the genes was found at lower levels in the blood of men with prostate tumors, while that from the sixth gene was found at higher levels.

The scientists put the test through its paces in a two-year study of 204 men with known prostate cancer, 110 men with benign prostatic hyperplasia (a harmless enlargement of the prostate that is responsible for many false positives on the PSA test) and 170 healthy men.

When used alone, the six-gene test detected about 86 percent of prostate tumors and had a specificity of 83 percent -- meaning that 17 percent scored as positive even though they didn't have a tumor. But when it was combined with the PSA test, the two detected 87 percent of tumors and the specificity was more than 91 percent -- only 9 percent of the positive scores were in error.

The researchers and the company are organizing a clinical trial of the test with 1,000 men, to begin this year. Karl Wassman, chief executive of Source MDx, said the new test probably will cost ''a couple of hundred dollars,'' much less than the $2,000 cost for a biopsy. The study was funded by Source, Dana-Farber and private donors.

LUNG CANCER DRUG

A cancer drug once regarded as a flop might re-emerge as an effective drug in some populations, Japanese researchers reported.

Gefitinib -- marketed as Iressa by AstraZeneca -- was approved in 2002 as a treatment for small-cell lung cancer, the most common form of the disease, but subsequent large studies failed to prove its efficacy. Oncologists noticed, however, that it apparently provided benefit for some Asians, nonsmokers with a mutation in a gene that serves as the blueprint for a protein called EGFR. About 10 percent of lung cancer patients carry the mutation.

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