ORLANDO--Whether women age 40 to 49 should have routine mammo-gram screening continues to be debated, but a University of Chicago study shows that women in this age group benefit from mammography screening as much as women over 50. Jeffrey D. Bradley, MD, lead study author, presented the finding at the annual meeting of the American Society for Therapeutic Radiation and Oncology (ASTRO).
"The significant outcome of this study is that there was no difference in failure-free survival between the younger and older women with mammogram-detected tumors," said Dr. Bradley, of the Department of Radiation and Cellular Oncology.
The study included 869 cases of stage I and II breast cancer treated with breast conservation and radiotherapy between 1984 and 1994. The median follow-up time was 43 months (range, 3 to 128).
Of this group, 318 (36%) presented with mammographic abnormalities and 551 (64%) with clinically detected lesions. The median age was 56 years, with a range of 22 to 88 years; 299 patients were under age 50.
The mammogram-detected tumors were found to be smaller than the clinically detected tumors (median size, 1.0 cm vs 1.8 cm). The mammogram-detected tumors were more likely to have ductal carcinoma in situ (DISC) associated with the infiltrating component (56% vs 44%) and were of a lower nuclear grade: 12% were nuclear grade 3 vs 29% for clinically detected lesions.
For all patients, the 5-year failure-free probability was significantly higher in mammogram-detected tumors vs clinically detected tumors (92% vs 82%), and there was a trend toward better overall survival (94% vs 85%), which, Dr. Bradley said, may reach significance with longer follow-up.
"The tumors that were detected through mammography were generally smaller and appeared less aggressive under the microscope than those tumors that were detected through physical exams," Dr. Bradley said.
Women under age 50 had a 90% probability of being failure free at 5 years if they had mammography-detected tumors, as opposed to 77% for clinically detected tumors (table). The overall survival rate for women under age 50 was 94% for mammography-detected tumors and 85% for clinically detected disease.
These figures were comparable to those in the over 50 group, D.r Bradley said. In this group, failure-free survival was 92% and 87%, respectively, for mammogram and clinical detection, and overall survival was 93% and 86%, respectively.
"The treatment results for women whose tumors were detected through mammography were better because the tumors were smaller and therefore easier to treat," Dr. Bradley said.
He concluded that mammography results in the diagnosis of smaller and lower grade breast cancers with a significantly better 5-year failure-free survival than lesions detected by clinical examination, and that the mammogram results appear to be the same for women over age 50 and under age 50.