TUESDAY, Aug. 31, 2004 (HealthDayNews) -- Women whose breast cancer is detected by a mammography have a better prognosis than women whose cancer is detected through other means, a new study finds.
The Finnish researchers report that those improved chances of survival lasted for up to 10 years after diagnosis, and the difference persisted even after compensating for such factors as age of the patient, grade of the cancer and whether lymph nodes were involved.
The research appears in the Sept. 1 issue of the Journal of the American Medical Association.
Although mammograms are becoming more common and they are picking up smaller tumors, doctors traditionally haven't considered the method of cancer detection important when choosing treatments or assessing risk of recurrence.
Most treatment decisions are based on whether the cancer has spread to the lymph nodes, the size of the tumor, the estrogen and/or progesterone receptor status, and the age of the woman at the time of diagnosis.
It's unlikely, however, that the study results will lead to mammography becoming another tool to help tailor therapy for women, some experts said.
"I wouldn't base my decision about whether to give chemo or not based on these results," said Dr. Ruth M. O'Regan, author of an accompanying editorial in the journal.
"If they confirmed this in another trial, then I definitely would take it seriously," added O'Regan, director of translational breast cancer research at the Winship Cancer Institute at Emory University in Atlanta.
The study, which looked at 2,842 Finnish women who had been diagnosed with breast cancer in 1991 or 1992, compared the survival outcomes of those who had had their tumors detected with mammography and those who had not. Because the rate of screening mammography among Finnish women is near universal (almost 90 percent), the study was a broad-based one. The participants were followed for an average of nine-and-a-half years. Various features of the tumors were also compared.
Those women whose tumors were detected by means other than mammography had almost double (90 percent) the risk for cancer recurrence outside the breast. Women whose tumors measured 11 millimeters to 30 millimeters in diameter and were detected by mammography had similar survival rates as women who had much smaller tumors (10 millimeters or smaller) that were detected without mammography screening.
The study results can be partially explained by a number of factors, including the size of the tumor, the hormone receptor status, and less likelihood of spread to the lymph nodes, the researchers said.
But the use of mammography appeared to play a role in the findings independent of these traditional risk factors for cancer.
"It's very interesting data. They did a very careful job of counting in all the prognostic factors that we usually take into account like tumor size and lymph nodes, and they still found that those who were screened did better," O'Regan said. "The interesting thing would be to look at the molecular level to see if there is some reason."
Another point to emphasize, said Dr. Julia Smith, an oncologist at New York University Cancer Institute, is that mammograms are picking up smaller tumors in older women. "That's not new but it reiterates an important point," she said.
Dr. Jay Brooks is head of hematology/oncology at the Ochsner Clinic Foundation New Orleans. "The message for women is that a mammogram is not a perfect test and if you have a mammogram today and four months from now you feel a lump in your breast, don't say, 'Because I had a mammogram four months ago, don't worry about it,?" he said.
"If you get your car worked on and get everything done and two weeks later the light goes on, don't you say something is wrong with the car? It's the same thing," he said.
For more on mammography, visit the National Cancer Institute.