When patients and physicians talk about “chemobrain,” the standard understanding of the problem is that it is a result of chemotherapy because it is usually noticed after chemotherapy begins.18 What the Phillips trial has done is suggest that chemotherapy may not be fully responsible for cognitive deficits. The results from this trial highlight the importance of using a radiotherapy comparison group, as those patients receiving radiotherapy also demonstrated similar decline in cognitive performance tasks.
What the cause or causes of this cognitive impairment is/are is a matter subject to debate. Eschewing treatment side-effects as the definitive reason for the impairment, the changes could be associated with the stress, anxiety, and mood changes associated with the diagnosis of the cancer.19 They may also be a result of altered brain structure and function due to the cancer.12–15
These findings also have significant clinical implications. Clinicians should discuss the possibility of the long-term cognitive effects of both chemotherapy and radiotherapy with their patients. Although cognitive deficits may last for years, they are domain specific and not global. Patients that report that cognitive deficits interfere with their ability to perform daily tasks should be further evaluated, and referred to a neuropsychologist to rule out other causes and be considered for other strategies to compensate for any deficits.17,20
- International Agency for Research on Cancer. Breast cancer incidence and mortality worldwide in 2008: summary. GLOBOCAN/International Agency for Research on Cancer website. http://globocan.iarc.fr/factsheets/cancers/breast.asp. Accessed March 15, 2012.
- Howlader N., Noone A.M., Krapcho M., et al., (eds). Surveillance epidemiology and end results. SEER Cancer Statistics Review, 1975–2008, based on November 2010 SEER data submission. National Cancer Institute. Bethesda, MD. http://seer.cancer.gov/statfacts/html/breast.html. Accessed March 15, 2012.
- Hassett M.J., O’Malley A.J., Pakes J.R., et al. Frequency and cost of chemotherapy-related serious adverse effects in a population sample of women with breast cancer. J Natl Cancer Inst. 2006;98(16):1108-1117.
- Keime-Guibert F., Napolitano M., Delattre J.Y. Neurological complications of radiotherapy and chemotherapy. J Neurol. 1998;245(11):695-708.
- Burstein HJ. Cognitive side-effects of adjuvant treatments. Breast. 2007;16(suppl2):S166-S168.
- Cognitive problems after chemotherapy. Chemobrain information series. CancerCare website. http://www.cancercare.org/publications/72-cognitive_problems_after_chemotherapy. Accessed March 21, 2012.
- Ahles T.A, Saykin A.J., McDonald B.C., et al. Longitudinal assessment of cognitive changes associated with adjuvant treatment for breast cancer: impact of age and cognitive reserve. J Clin Oncol. 2010;28(29):4434-4440.
- Schagen S.B., Hamburger H.L., Muller M.J., et al. Neurophysiological evaluation of late effects of adjuvant high-dose chemotherapy on cognitive function. J Neurooncol. 2001;51(2):159-165.
- Correa D.D., Ahles T.A. Neurocognitive changes in cancer survivors. Cancer J. 2008;14(6):396-400.
- Wefel J.S., Saleeba A.K., Buzdar A.U., Meyers C.A. Acute and late onset cognitive dysfunction associated with chemotherapy in women with breast cancer. Cancer. 2010;116(14):3348−3356.
- Deprez S., Amant F., Smeets A., et al. Longitudinal assessment of chemotherapy-induced structural changes in cerebral white matter and it correlation with impaired cognitive functioning. J Clin Oncol. 2012;30(3):274-281.
- de Ruiter M.B., Reneman L., Boogerd W., et al. Cerebral hyporesponsiveness and cognitive impairment 10 years after chemotherapy for breast cancer. Hum Brain Mapp. 2011;32(8):1206-1219.
- Inagaki M., Yoshikawa E., Matsuoka Y., et al. Smaller regional volumes of brain gray and white matter demonstrated in breast cancer survivors exposed to adjuvant chemotherapy. Cancer. 2007;109(1):146−156.
- McDonald B.C., Conroy S.K., Ahles T.A., et al. Gray matter reduction associated with systemic chemotherapy for breast cancer: a prospective MRI study. Breast Cancer Res Treat. 2010;123(3):819-828.
- Kesler S.R., Bennett F.C., Mahaffey M.L., Spiegel D. Regional brain activation during verbal declarative memory in metastatic breast cancer. Clin Cancer Res. 2009;15(21):6665-6673.
- Kesler S.R., Kent J.S., O’Hara R. Prefrontal cortex and executive function impairments in primary breast cancer. Arch Neurol. 2011;68(11):1447-1453.
- Phillips K.M., Jim H.S., Small B.J., Laronga C., Andrykowski M.A., Jacobsen P.B. Cognitive functioning after cancer treatment: a 3-year longitudinal comparison of breast cancer survivors treated with chemotherapy or radiation and noncancer controls [published online ahead of print December 12, 2011]. Cancer. 2012; http://onlinelibrary.wiley.com/doi/10.1002/cncr.26432/full. Accessed March 14, 2012.
- Hede, K. Chemobrain is real but may need new name. J Natl Cancer Inst. 2008;100(3):162−163, 169.
- Schilder C.M., Seynaeve C., Linn S.C., et al. Cognitive functioning of postmenopausal breast cancer patients before adjuvant systemic therapy, and its association with medical and psychological factors. Crit Rev Oncol Hematol. 2010;76(2):133−141.
- Ganz P.A. “Doctor, will the treatment you are recommending cause chemobrain?” J Clin Oncol. 2012;30(3):229-231.