NEW YORK (Reuters Health) - An analysis of the results of several studies confirm previous reports suggesting that chemotherapy offers little or no survival benefits for young women with estrogen receptor (ER)-positive breast cancers and, if given, it should not be the sole second-phase, or "adjuvant" therapy.

"Developing breast cancer at a young age is very worrying in terms of survival," lead researcher Dr. Jos J. A. van der Hage, from Leiden University in the Netherlands, said in a statement. "But some young women may be undergoing not only unpleasant but also unnecessary chemotherapy."

In the current analysis, the researchers examined data from 480 women with early-stage breast cancer enrolled in one of four EORTC (European Organization for Research and Treatment of Cancer) trials. All of the subjects were premenopausal -- younger than 40 years of age -- and the average follow-up period was 7.6 years.

During follow-up, 155 patients died or experienced a distant recurrence, according to the report appearing in the current online issue of Breast Cancer Research.

Patients with ER-positive cancers were significantly more likely to have a longer overall survival than those with ER-negative cancers, the team reports.

Among the patients who received prolonged adjuvant chemotherapy, however, the difference in survival rates was minimal (70 percent versus 75 percent, favoring the ER-negative group, and rates of metastasis-free survival were 59 percent versus 70 percent, respectively.

These results suggest that chemotherapy had a beneficial effect for women with ER-negative tumors, but had minimal or no effect on ER-positive cancers.

Similar survival differences were noted for women with or without progesterone receptor-positive tumors, the report indicates.

"Adjuvant chemotherapy is a well established, but ineffective treatment in ER-positive breast cancer patients aged 40 years or less," van der Hage emphasized. "Hormone responsiveness is the key to tailoring therapy in the future fight against this disease for young women."