What are the effects of chemotherapy (chemical therapy)?

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Last updated: February 11, 2025View editorial policy

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From the Guidelines

Chemotherapy has numerous detrimental side effects, including nausea, fatigue, hair loss, and cognitive impairment, which can significantly erode the quality of life of cancer survivors.

Effects of Chemotherapy

  • Cognitive impairment, also known as "chemobrain" or "chemofog," is a common side effect of chemotherapy, characterized by a decline in performance in cognitive function related to learning, attention, executive functions, memory, multitasking, and processing speed 1.
  • The prevalence of clinically significant cognitive impairment varies between 17% and 78% with self-reported measures, and approximately 33% using objective neurocognitive testing in post-chemotherapy patients with breast cancer 1.
  • Chemotherapy-induced cognitive impairment is likely multifactorial, and the predictors and possible interventions are not well understood 1.
  • Cognitive function has been prospectively investigated in patients participating in the CO-SOFT sub-study, and no evidence was provided that adding OFS to adjuvant oral ET substantially affects global cognitive function 1.
  • Verbal learning/memory is the only domain where ET patients performed worse than both non-cancer and breast cancer controls, suggesting specific adverse effects on this domain 1.
  • Patient-reported symptoms (forgetfulness, difficulty with concentration, fatigue, distractibility, and difficulty with word finding) rarely correlate with neuroimaging studies and neuropsychiatric evaluation 1.
  • Growing evidence supports the patient experience of cognitive dysfunction associated with cancer and its treatment, with deficits limited to verbal and visuospatial abilities 1.
  • Chemotherapy has been associated with impaired subjective self-reported cognitive functioning in breast cancer patients up to 2 years after diagnosis, with the impact most pronounced in younger patients 1.

From the Research

Effects of Chemotherapy on the Body

  • Chemotherapy can cause a range of short-term and long-term side effects, including alopecia (hair loss), chemotherapy-induced peripheral neuropathy, chemotherapy-induced nausea and vomiting, cardiotoxicity, diarrhea, infertility, and chemo brain 2
  • Common side effects of chemotherapy include fatigue, nausea, vomiting, mucositis, hair loss, dry skin, skin rash, bowel changes, anemia, and an increased risk of acquiring infection 3
  • Chemotherapy can also cause inflammation of the heart, lungs, liver, kidney, neurons, and disturbance of coagulation cascade 3

Effects of Chemotherapy on Energy Metabolism

  • Chemotherapy can induce serious metabolic alterations, leading to an energy imbalance and worsening prognosis 4
  • Studies have shown a significant decrease in resting energy expenditure (REE) 1-month post-chemotherapy, with changes accompanied by variations in body composition (fat mass and fat-free mass) 4
  • The Harris-Benedict equation tends to underestimate REE, stressing the need for adequate assessment to meet patients' energy requirements and support dietary needs 4

Management of Chemotherapy-Induced Side Effects

  • Supportive care and approved treatments are available to manage some chemotherapy-induced side effects, while others are unavoidable 2
  • The use of antiemetic medications, such as serotonin 5-HT(3) receptor antagonists, can help manage nausea and vomiting associated with chemotherapy 5
  • However, these medications can also have adverse effects, such as headache, dizziness, constipation, and diarrhea, and should be used with caution in susceptible patients with co-morbidities 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Chemotherapy: how to reduce its adverse effects while maintaining the potency?

Medical oncology (Northwood, London, England), 2023

Research

Chemotherapy.

Cancer treatment and research, 2023

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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