Cancer Test Gets Mixed Reviews
A small California company made headway Friday in the race to develop commercial applications stemming from human genome research.
Genomic Health Inc. of Redwood City reported that in two studies its genetic test for women with early breast cancer pinpointed which patients were most likely to benefit from chemotherapy, as well as which ones were most likely to relapse after surgery.
Some experts said the test could one day allow doctors to tailor treatments to suit each patient’s cancer -- a step toward the era of personalized medicine.
“This test has the potential to change medical practice” for breast cancer treatment, said JoAnne Zujewski, a senior investigator with the National Cancer Institute, which helped Genomic Health design its studies.
At the same time, Zujewski said, patients should not rely on the test alone to make decisions about their treatment.
In the medical community, reaction to the research data, which were presented at a medical conference in San Antonio on Friday, was mixed.
One doctor said the test might help women decide whether to undergo chemotherapy, which has many side effects, including severe nausea, vomiting and hair loss. Women unlikely to benefit from treatment could forgo the drugs.
“I am sure we have been over-treating some patients,” said Mark Pegram, director of the women’s cancer program at UCLA’s Jonsson Cancer Center.
Another doctor was cautious, saying that although the research was impressive, the test needed more study because the stakes for patients were high.
“Two years from now, I would not want to explain to a woman who did not get chemotherapy why her cancer recurred,” said Michael Samoszuk, director of hematopathology at UC Irvine Medical Center.
Genomic Health was founded in 2000 to develop products based on the decoding of the human genome. The company, which is privately held, was started by former employees of biotechnology giant Genentech Inc. and Incyte Corp., a company focused on genetic research. Genomic Health is backed by investors including Kleiner Perkins Caufield & Byers, Credit Suisse First Boston and Pfizer Inc.
The company began offering the test to hospitals this year. Because Genomic Health processes tumor samples in its own labs, the test does not need Food and Drug Administration approval, the company said.
Steven Shak, the company’s chief medical officer, said the studies should boost acceptance of the test among doctors and health insurers. Some health plans currently reimburse the $3,460 cost of the test, he said, but only on a case-by-case basis. Shak contends that the test, called Oncotype DX, is more accurate than measures doctors currently use for risk assessment, such as the size of the tumor and the age of the patient.
The research reported Friday focused on a type of cancer that affects 100,000 women in the U.S. each year, about half of all new breast cancer cases. These tumors need estrogen to grow and have not infiltrated the lymph nodes.
Women with this type of disease typically receive tamoxifen, a drug that works to block estrogen after surgery to remove their tumors. Many women also receive chemotherapy as a precaution to kill any remaining cancer cells, though doctors have long suspected that few women benefit much from the drugs.
The Genomic Health test looks at 21 genes that appear to play a role in how breast cancer spreads or responds to treatment. After examining a tumor sample to see whether those genes are active, the company calculates a “recurrence score” for the patient. A low score means the cancer is unlikely to return and spread beyond the breast.
A study led by Norman Wolmark, chairman of the department of human oncology at Allegheny General Hospital in Pittsburgh, used the Genomic Health test on tumor samples taken from 668 women who had been treated for breast cancer between 1982 and 1988. After assigning a recurrence score to each sample, researchers matched their results to patients’ medical records.
Those findings were published online by the New England Journal of Medicine on Friday. They found that after 10 years cancer returned in 30% of patients with high scores. The disease came back in only 7% of patients with low scores.
In a separate study, also led by Wolmark, researchers looked at samples taken from 651 women with breast cancer. They found that women in the low-risk category -- about 50,000 each year -- derived little if any benefit from chemotherapy. But the drugs improved the odds of women in the high-risk group, about 25,000 new cases each year. Findings from that study were announced at the San Antonio Breast Cancer Symposium on Friday.
“These results are striking,” the National Cancer Institute’s Zujewski said at a news conference.
UCLA’s Pegram said one of his patients opted for chemotherapy after her test results showed she had an elevated risk of recurrence. Pegram initially recommended against chemotherapy because the patient’s tumor was relatively small.
“I know that she is very happy that she had that test,” he said.
Still, there are the doctors who believe the test should be studied further. They noted that researchers in the chemotherapy study looked at patients who received doxorubicin and paclitaxel, which is just one of many drug combinations used to treat the disease.
Cancer genetics expert Howard McLeod of Washington University in St. Louis said the test was not particularly useful to patients in the low-risk group. He said a clinical trial was needed to show whether patients defined as low risk could safely forgo chemotherapy, but such an experiment would be costly.
“The problem with these tests is that it does not tell you what to do if you have a negative result,” McLeod said. Even a small chance of cancer recurrence might be unacceptable to patients, he said.
“I can look at this objectively and say this is a great step forward,” he said.
“But if it is your mother or your sister, you might think about erring on the side of over-treating.”
