Effect of undertreatment on the disparity in age-related breast cancer-specific survival among older women

Abstract

Assess the relationship between age and breast cancer-specific survival among older women and determine whether the observed age-related disparities in survival is explained by differences in breast cancer treatments received. Women ≥65 years old at diagnosis with stage I–IIIA breast cancer diagnosed between 1997 and 1998 were recruited from four regions of the United States and followed prospectively for 5 years after diagnosis. Data was obtained from tumor registries, medical records, and telephone interviews. The primary endpoint was breast cancer-specific survival. Our independent variables were age operationalized as ≤75 years vs. >75 years, and receipt of recommended guideline therapy, adapted from the National Institutes of Health guideline consensus conference. Of 689 women, 36% were >75 years. Women >75 years were less likely to have received the following; axillary lymph node dissection (84% vs. 93%, P = 0.0003), radiotherapy (40% vs. 54%, P = 0.0003), definitive primary therapy (71% vs. 84%, P < 0.0001), chemotherapy (9% vs. 28%, P < 0.0001), and guideline therapy (31% vs. 54%, P < 0.0001). The 5-year breast cancer-specific survival was 95% (95% confidence interval [CI], 90%, 97%) for those ≤75 years who received guideline therapy, 94% (95% CI, 90%, 97%) for those ≤75 years who did not receive guideline therapy, 96% (95% CI, 88%, 99%) for those >75 years who received guideline therapy and 83% (95% CI, 74%, 89%) for those >75 years who did not receive guideline therapy, (P = 0.002) by the log-rank test. Receipt of guideline therapy may reduce the age-related disparity in breast cancer survival among older women.