Risk of dementia in older breast cancer survivors: a population-based cohort study of the association with adjuvant chemotherapy

J Am Geriatr Soc. 2009 Mar;57(3):403-11. doi: 10.1111/j.1532-5415.2008.02130.x.


Objectives: To assess whether there is an association between delivery of adjuvant chemotherapy to older women with breast cancer and development of dementia over time.

Design: Retrospective cohort study using Surveillance, Epidemiology, and End Results (SEER) data linked to Medicare claims data.

Setting: Women residing in geographic areas included in the SEER registry.

Participants: Women aged 66 to 80 diagnosed with non-metastatic invasive breast cancer from 1992 to 1999 were included. It was determined whether patients had undergone chemotherapy within 6 months of diagnosis.

Measurements: Whether women developed dementia over time was determined using diagnostic codes. The effect of adjuvant chemotherapy on development of dementia was evaluated, adjusting for confounders using a proportional hazards model stratified for age.

Results: Twenty-one thousand three hundred sixty-two women met selection criteria; 2,913 received chemotherapy, and 18,449 did not. Women who received chemotherapy were younger than those who did not (median aged 70 vs 73; P<.001). Median follow-up time was 59 months. After controlling for other factors, it was found that chemotherapy was not associated with a greater risk of development of dementia over time for any age group (hazard ratio for dementia in women receiving chemotherapy: aged 66-70=0.83, 95% confidence interval (CI)=0.48-1.45, P=.5; aged 71-75=0.74, 95% CI=0.46-1.18, P=.2; aged 76-80=0.49, 95% CI=0.28-0.88, P=.02).

Conclusion: Receipt of chemotherapy in older women with breast cancer was not associated with a greater risk of dementia diagnosis over time; very elderly women who undergo chemotherapy may be at lower baseline risk. The use of a claims-based definition of dementia limited the study.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antineoplastic Combined Chemotherapy Protocols / adverse effects*
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / epidemiology
  • Chemotherapy, Adjuvant
  • Cohort Studies
  • Comorbidity
  • Dementia / chemically induced*
  • Dementia / diagnosis
  • Dementia / epidemiology
  • Female
  • Geriatric Assessment / statistics & numerical data
  • Humans
  • Proportional Hazards Models
  • Retrospective Studies
  • Risk
  • SEER Program
  • Survivors*
  • United States