**1. Introduction**

#### **1.1 Cancer: definition and prevalence**

Cancer is defined as the pathological tissue growth caused by a lengthy and persistent proliferation of abnormal cells which causes invasion and destruction of body tissues [1].

Cancer, neoplasm, or malignant tumors are generic terms used in an indistinct way to designate a wide group of diseases that can affect any part of the organism. But

cancer has a definite characteristic: the accelerated multiplication of abnormal cells that extend far beyond their usual limits, even invading other body parts, which is called metastasis. The metastatic extension is the principal cause of death by the disease [2].

According to the World Health Organization (WHO), cancer is the principal cause of death worldwide, being almost one of six deaths registered annually and in 2020, the total amount of cancer-related deaths was nearly 10 million [2].

Approximately 400 thousand children get diagnosed with any type of cancer annually. However, the incidence rises with age due to the loss of cellular repair mechanisms and the accumulation of risk factors [2].

Besides age, smoking is another important cancer risk factor, being almost onethird of cancer-related deaths. Other risk factors are increased body mass index, a sedentary lifestyle, alcohol intake, and low fruit intake [2].

## **2. Anxiety: definition, prevalence, and clinical characteristics**

Anxiety is a natural adaptive mechanism that allows the human being to be alert to potential dangers. In a way, it delivers a sense of precaution for usual dangers and, in moderate intensity and short intervals, can help us focus, maintain focus, and face challenges.

As with other emotions, when the anxiety presents disproportionately for a specific situation or even in the absence of any evident danger, the beneficial effect is exceeded.

According to WHO, in 2015 the world prevalence of anxiety disorders was 3,6%. As with depression, anxiety disorders are more frequent in women than in men (4.6% versus 2.6% worldwide) [3].

It is calculated that approximately 13% of the general population has a phobic anxiety disorder, like social phobia, whereas 7% of women and 4.3% of men have specific phobias. Generalized anxiety disorder (GAD) is presented in 3–5% of the adult population. Obsessive-compulsive disorder (OCD) affects almost 2.3% of adults. Panic disorder is less frequent and is diagnosed in less than 1% of the population. Posttraumatic stress affects at least 1% of the population, with higher incidences in war veterans and survivors of physical or sexual abuse [3].

As physical signs and symptoms, we can find palpitations, tachycardia, hyperventilation, excessive sweating, the feeling of chest oppression or dyspnoea, tremors, dizziness, and fainting. As mental signs and symptoms, we have constant worry, weariness, irritability, and trouble focusing and falling asleep [4].

The anxiety that occurs in a high level of intensity and extends for long periods begins to produce a psychosocial functioning deterioration, interfering with normal activities and in more than one sphere (social, family, academic, and work, among others). On the other hand, the intensity and duration also produce physiological damage.

It is important to promptly recognize these signs and symptoms and have an integral medical evaluation.

## **3. Depression: definition, prevalence, and clinical characteristics**

Mental health problems, especially depression, represent a public health concern due to their high prevalence, morbimortality, and incapacity generated in a long term.

Depression is different from mood changes and brief emotional responses to the problems of daily life and can become a serious health problem, especially when it

occurs recurrently and with moderate to severe intensity, being associated with suicide in some cases.

Depression is a common disease throughout the world, as it is estimated to affect 5% of adults and 5.7% of elderly adults (over 60 years of age) [5]. According to the WHO, it is estimated that, in 2015, the proportion of the world population with depression was 4,4%. Although since the start of the 2019 COVID pandemic, the prevalence of anxiety and depression has increased by up to 25% [6].

In general, depression is defined as a disease characterized by a state of persistent sadness that is accompanied by a loss of interest in previously enjoyed activities. In addition, the patient loses the ability to carry out daily activities. All of this occurs for at least two weeks. In many cases, when depression is chronic, it is difficult for the patient to identify sadness or even remember what activities generated enjoyment: the only thing noticeable is the difficulty to participate in their different spheres (social, sentimental, work, academic, etc.) [7].

People with depression often have several of the following symptoms: loss of energy, disturbances in sleep pattern, sleeping more or less than usual; changes in the appetite; anxiety; decreased concentration; indecision; concern; feeling worthless, guilty, or hopeless; and frequent thoughts related to death, with self-harm, suicidal thoughts or attempts that often lead to death [8].

People exposed to violence frequently experience a variety of reactions including anxiety, stress, frustration, fear, irritability, anger, difficulty concentrating, loss of appetite, and nightmares [9].

Depression interferes with daily life, the ability to work, sleep, study, eat and enjoy life [9]. On the other hand, people with depression present cognitive distortions, such as negative thoughts about themselves, the environment or the future, and alterations in cognitive performance such as difficulties with concentration, memory, and the ability to make decisions, which also influence the overall functioning of the person [8].

When talking about mental health, it is always important to emphasize that depression is not a sign of weakness. It can be treated with psychotherapy, antidepressant medication or with a combination of both methods, the latter being what has shown better and longer-lasting results. A second sphere that must be targeted, within the treatment, is the generation of healthy lifestyles.

It is very common for patients with depression to have a family history of the disease. However, depression can also occur in people without a family history.

The causes of depression are multiple since several genetic, biological, and environmental factors intervene in it.

Regarding genetic factors, several studies have reported that around 200 genes are related. These genetic factors are related to alterations of neurotransmitters, cytokines and hormones, whose actions induce structural and functional modifications in the central nervous system, the endocrine system, and the immune system, which increase the risk of suffering from major depression [10].

The biological causes are explained both by structural alterations in the brain as well as functional alterations in neurotransmitters (serotonin, norepinephrine, and dopamine). However, more studies are still needed to understand the mechanisms of the efficacy of antidepressants [11, 12].

Among the environmental or psychosocial factors, it has been observed that depression is associated with previous stressful events, especially when these occur at an early or older age if the subject has been subjected to prolonged stress. The stress that accompanies the first episode produces long-term changes in brain physiology that can produce variations at the structural level and in the functioning of different brain areas [13, 14].

## **4. Terminally ill patients**

The importance of determining that a patient is in the terminal phase (end of life) of the disease is aimed at early identification of the needs and special care that help the patient and his family [15].

Thus, the terminal patient is the one who has an advanced, progressive, and incurable disease, with a lack of reasonable possibilities of responding to a specific treatment, who presents numerous problems or intense symptoms, with a loss of autonomy or progressive fragility that represent a great emotional impact for himself, his relatives and the therapeutic team that cares for him, and his situation being related, implicitly or explicitly, to the presence of death and a life expectancy of fewer than six months. All of this is associated with high demand and use of resources [16, 17].

## **5. Cancer patient in terminal phase**

On the other hand, the cancer patient in the terminal phase is the one with a histological diagnosis of cancer demonstrated in clinical stage IV; brain, spinal cord, liver or multiple lung metastases; who have received effective standard therapy and/ or are in a situation of little or no possibility of responding to active or specific treatment [18].

Medicine attempts to preserve life, we see life expectancy rates are increasingly higher, however, it is inevitable getting to prevent death in spite of the multiple human and technological efforts and the advance in science.

It is in light of this reality that medical practitioners face patients in terminal, a human being that encounters great fears—resulting from the disease itself – to face death as an imminent situation and along with the patient, relatives and friends surrounding them.

Just there is where the medical practitioner and the therapeutic team are faced to great challenges, on the hand, relieving physical symptomatology, and on the other hand, dealing with those psychological needs. Therefore, the awareness of healthcare personnel facing this critical situation is essential to effectively help in the relief of patient and their family.

According to the Institute of Medicine, the "Good death" is one that is: "free from avoidable distress and suffering for the patient, family and caregivers, in general accord with the patient's and family's wishes, and reasonably consistent with clinical, cultural, and ethical standards" [19, 20].

The objective of the health personnel who oversees the patient in palliative care must be to reach the "Good death" and the steps to get to that state are aimed at relieving the mental, physical, family state, etc. It is there that psychiatric disorders take on great importance, because, although they are very frequent and with a high incidence, many times they are not detected early [15].

## **6. Psychiatric disorders in cancer patients**

Within the main psychiatric disorders, we focused on the most critical three, which are anxiety, depression, and delirium.

*Anxiety, Depression, and Delirium in Terminally Ill Cancer Patient DOI: http://dx.doi.org/10.5772/intechopen.107325*

It is evident that assessing the symptoms and signs of the different psychiatric disorders is difficult in an oncological patient in a terminal state of illness, which is why it requires greater knowledge of the most frequent psychiatric pathologies, as well as the earliest possible management of the patient to achieve a better result that improves the quality of life of our patient, as well as a "good death".

As Stiefel et al. mention underdetection and undertreatment of depression is a serious problem in palliative care [21]. In palliative care patients, anxiety and depression need to be actively screened for and dealt with using a multidisciplinary approach [22].

## **7. Anxiety in cancer patients**

It is also important to refer to specific situations that cancer patients experience, such as radiotherapy treatments, which will be an important factor in the patient's quality of life. When the patient is presented with the different types of treatments, the first reactions to the proposed treatment arise first and special attention must be paid since many patients have preconceived ideas about side effects. This is where the role of the doctor is essential to start the new therapeutic approach, clarifying doubts [23, 24].

In the case of patients undergoing radiotherapy, some degree of anxiety has been observed, expressed mainly as concern about the treatment, side effects, what is going to happen in the near future, depression and social isolation caused mainly by fear of the treatment and its side effects and impact on quality of life [23, 24].

In this chapter we focus on the cancer patient in a terminal situation, therefore, the intention of the therapeutic treatment with radiotherapy will have the objective of improving the quality of life and not a curative intention.

Most of the effects of radiation therapy on normal tissue are attributed to cytotoxicity [25].

In the terminally ill cancer patient, the approach of the health personnel and especially of the doctor must be even more global than in any other circumstance.

We must always remember that we are dealing with a patient who not only has a feeling of uncertainty, of fear of what is going to happen, who has faced the diagnosis of "cancer" and who is also now in a terminal situation, with a logical and understandable increase of their fears, concerns, denial, physical and psychic pain, fear for their loved ones, with a very large and deep mixture of feelings that translate in a large majority of patients to some degree of anxiety, depression that the sooner we diagnose, we will be able to offer the patient and their family better adherence to treatment, a better quality of life and a more dignified death.

In studies such as the one carried out by Jung-Ah Min et al., it is observed how a high level of resilience contributes to less emotional stress in hospitalized patients. Likewise, they observe the same relationship in patients with metastatic cancer. Thus, it appears that the influence of resilience is independent of and not attributed to the potential effects of a well-known variety of factors contributing to emotional stress [26].

Resilience is defined as the dynamic capacity to successfully maintain or recover a healthy mental state in the face of significant life risks or adversities [27].

In the article published by R.L. Gould et al. evidence is shown for the feasibility and acceptability of acceptance and commitment therapy (ACT), an acceptancebased behavioral therapy, with a strong evidence base in pain and a growing evidence base in mental health conditions [4].

## **8. Depression in cancer patients**

The diagnosis of cancer is often related to emotional and mental disorders such as depression and anxiety [26].

Psychiatric disorders, mainly anxiety and depression, occur between 25 and 50% of patients with advanced cancer; however, many of these are underdiagnosed since they are considered a part of the disease's own discomfort [28].

The comorbidity between cancer and psychiatric problems can generate several complications, ranging from non-adherence to any treatment, isolation of the patient, greater symptoms and suffering, and increased complications of recovery from surgery [29].

However, making a psychopathological diagnosis of depression in cancer patients can be difficult, due to the confluence of psychological and somatic symptoms typical of neoplastic disease. The very nature of cancer generates emotional discomfort that can range from a normal adaptive reaction to the disease to the presence of a set of signs and symptoms that, depending on the intensity and psychosocial involvement of the patient, could require psychotherapeutic and psychopharmacological treatment [30].

Insomnia, and in general, sleep disorders associated with anxiety/depressive disorders are one of the most prevalent symptoms, affecting 40–60% of cancer patients. Despite the importance of adequate sleep in cell repair processes, insomnia is one of the most common symptoms and one that generates high levels of stress but often does not receive the attention it deserves when compared to other problems presented by these patients such as nausea and pain, etc. [31].

The use of antidepressants and other psychotropic drugs is necessary for the presence of feelings of worthlessness, guilt, or hopelessness associated with frequent thoughts of death, self-harm, or suicide attempts. Pharmacological treatment can also help with irritability, anger, loss of appetite, insomnia, and difficulty concentrating and making decisions [32].
