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Cancer is frequently associated with significant anaemia, either as a result of the disease itself or the effects of cancer treatment, particularly cytotoxic chemotherapy, radiation treatment or concurrent administration of both. The prevalence of anaemia varies according to the type of tumour. About 50% of patients with solid tumours present with anaemia at diagnosis. It is defined as an inadequate circulating level of haemoglobin or red blood cells. The pathophysiology of tumour-related anaemia is multifactorial. Tumour-associated factors such as tumour bleeding, haemolysis and deficiency in folic acid and vitamin B12 can be acute or chronic.
Treatment-associated factors may aggravate the incidence of anaemia and they may compromise patient’s tolerance of treatments, resulting in the need to reduce the duration or intensity of those treatments. Dose-intensified regimens and combined modality schedules of chemotherapy and intensified radiotherapy result in a higher degree of anaemia. The increase in the total radiation dose administered with the new radiotherapy techniques, such as conformal or intensified modulated radiation treatment (IMRT), combined with the newer chemotherapeutic agents, such as taxanes, which are strongly myelosuppressive, are possibly responsible for the increased incidence of anaemia and might require treatment interruptions, which compromise efficacy.
The clinical manifestation and severity of anaemia vary considerably among individual patients and is associated with its own set of debilitating signs and symptoms it can have a significant effect on morbidity and mortality, as well as on the level of care that patients require. Chronic anaemia can result in severe organ damage affecting the cardiovascular system, immune system, lungs, kidneys and the central nervous system. In addition to physical symptoms, the subjective impact of cancer-related anaemia on quality of life (QoL), mental health and social activities may be substantial. A common anaemia-related problem is fatigue, which impairs the patient’s ability to perform normal daily activities.
Tumour Hypoxia and Anaemia,the Impact on Treatment Efficacy
Another aspect of anaemia in patients with malignant disease is the effect on the tumour itself, and in several cancers such as cervical carcinoma, head and neck cancer, prostate and lung cancer it is associated with poor prognosis. Hypoxia is a characteristic pathophysiological property of solid tumours that occurs across a wide range of experimental and human malignancies. Hypoxic regions have been identified in locally advanced breast and cervical tumours, head and neck cancer, prostate cancer, pancreatic cancer, rectal cancer, brain tumours, soft tissue sarcoma and malignant melanoma. Tumour hypoxia, acting through direct or indirect mechanisms, or both, may contribute to resistance to radiotherapy, some chemotherapy regimens and chemo-radiation which can lead to a poorer clinical outcome.
Tumour cells can become resistant to cancer treatments because of hypoxia; this is due to decreased oxygen transport capacity as a result of tumour-associated anaemia, which can contribute to the development of hypoxia. Owing to an abnormal microenvironment, solid tumour tissue is often hypoxic. Hypoxia may be more prevalent in anaemic patients than in patients with normal haemoglobin (Hb) levels.