Breast Cancer Research and Treatment

, Volume 95, Issue 2, pp 125–129

The (mis)classification of chemo-fog – methodological inconsistencies in the investigation of cognitive impairment after chemotherapy

  • Val Shilling
  • Valerie Jenkins
  • Ivonne Solis Trapala
Clinical trial



A growing number of studies report cognitive impairment after chemotherapy; indeed the phenomenon of chemo-fog is now almost universally accepted. We are concerned however that there is little if any consistency in the way in which patients are classified as showing cognitive impairment or not. We aim to demonstrate that different methods of analysis produce markedly different results, making the true extent of impairment unclear.


We analysed data from 92 breast cancer patients 4 weeks post-chemotherapy and from 42 healthy controls using 7 different methods, each taken from a different research paper in the area of cognitive impairment post-chemotherapy.


The extent of impairment was dependent on the method of analysis. Impairment ranged from 12 to 68.5% in the chemotherapy group and from 4.8 to 64.3% in the healthy control group.


This brief report highlights the contrasting degrees of cognitive impairment calculated by using legitimate statistical methods and demonstrates the need for a collaborative effort to standardise our methods that we might better understand the phenomenon of chemo-fog.


breast cancer chemotherapy cognitive impairment 


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Copyright information

© Springer 2005

Authors and Affiliations

  • Val Shilling
    • 1
  • Valerie Jenkins
    • 1
  • Ivonne Solis Trapala
    • 2
  1. 1.Cancer Research UK Psychosocial Oncology GroupBrighton and Sussex Medical School University of SussexFalmer East SussexUK
  2. 2.Centro de Investigacion en Matematicas, A.CGuanajuato GtoMexico
  3. 3.Cancer Research UK Psychosocial Oncology GroupBrighton and Sussex Medical School University of Sussex Falmer East SussexUK

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