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

Objectives 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. Methods 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. Results 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. Conclusion Receipt of guideline therapy may reduce the age-related disparity in breast cancer survival among older women.