According to the American Cancer Society, in the United States, there were around 1.9 million new cancer cases in 2021. Approximately 600,000 people died of cancer in the same year, making it the second leading cause of death in the United States, right after heart disease.

There is no doubt that cancer causes severe emotional distress not only to the cancer patient but also to their family and friends. The diagnosis of cancer is often accompanied by feelings of fear, anxiety, anger, and depression.

But can cancer cause mental illness?

This article aims to explore the connection between cancer and mental illness and provide useful information for cancer patients and their loved ones.

MENTAL ILLNESS, A DEFINITION

The National Institute of Mental Health estimates that, as of 2020, around 1 in 5 US adults live with a mental illness.

Mental illness is a very broad term that includes a wide range of conditions, from anxiety and depression to more serious disorders such as schizophrenia and bipolar disorder.

It is important to note that not all mental illnesses are created equal and that different people can experience very different symptoms. Similarly, the causes of a mental disorder can vary greatly, and there is no single explanation for why someone might develop a mental illness.

When talking about mental illness and cancer, there are two paths we need to consider 

– the direct path, in which cancer might directly affect certain brain and central nervous system functions and therefore cause mental illness. 

– the indirect path, in which cancer might indirectly lead to mental illness through other physical symptoms or social factors.

DIRECT IMPACT OF CANCER

The most obvious way cancer could cause mental disorders is by directly affecting the brain and central nervous system.

Certain brain tumors can cause personality changes and mood disorders. 1 in 3 people diagnosed with a brain tumor have experienced personality changes due to the tumor itself or its treatment.

For example, tumors located in the frontal lobe (the area of the brain responsible for decision-making, planning, and social behavior) can cause changes in behavior and personality, as well as difficulties with executive function (the ability to plan and organize).

Tumors located in the temporal lobe (the area of the brain responsible for emotion and language) can cause problems with memory, mood, and behavior.

The pituitary gland, located at the base of the brain, is responsible for producing hormones that regulate many important body functions. Tumors in this area can lead to problems with hormone regulation, which can, in turn, cause a wide range of physical and mental symptoms.

These are just a few examples – there are many other ways that cancer can affect the brain and central nervous system and potentially cause a psychiatric disorder.

Can this type of mental illness be treated?

Whether or not the mood disorders or personality changes in the case of are permanent depends on several factors, including the type of cancer, where it is located in the brain or central nervous system, and how far it has progressed.

If there is no damage to the brain and the cancer is successfully removed or treated, the mood disorder or personality changes may be temporary.

However, if cancer has caused damage to the brain, if it continues to grow, or if it cannot be treated, the mood disorder or personality changes may be permanent.

INDIRECT IMPACT OF CANCER

Cancer can also indirectly lead to mental illness due to the psychological distress that often accompanies a cancer diagnosis.

A 2018 study published in the BMJ found that depression affects up to 20% of cancer patients, while anxiety can be found in 10% of those with cancer.

These mental health conditions can develop due to many different factors, including the fear that the cancer may lead to death, worries about financial stability or loss of employment during treatment, social isolation as a result of changes in appearance or increasing fatigue and pain, relationship strain caused by these challenges, frustration and worry over missed work or school, and a loss of confidence in the ability to function socially or professionally.

Unfortunately, mental health conditions can also affect cancer treatment outcomes. Research has found that clinical depression is associated with a  30% increase in cancer mortality risk in breast cancer patients. This may be due to a couple of reasons:

• Unhealthy lifestyle factors – People who are depressed are more likely to smoke, eat poorly, and exercise less, which can impact cancer treatment outcomes.
• Poor compliance with treatment – People who are depressed may be less likely to take their medication as prescribed or follow through with other recommended therapies.

Can this type of mental illness be treated?

Mental health issues caused by the cancer diagnosis rather than cancer itself are often treatable with psychotherapy and medication.

Therapies such as cognitive-behavioral therapy (CBT) can help patients identify the thought patterns and behaviors that are contributing to their mental illness and then change those thought patterns or behaviors to improve mood, relieve anxiety, and reduce stress.

Medication is also commonly used to treat mental illness, and there are many different types of medication that can be effective for depression, anxiety, and other conditions.

It is important to talk to a doctor or mental health professional if you are experiencing any symptoms of mental illness, as early diagnosis and treatment can improve the chances of a successful outcome, both in terms of mental health and cancer outcomes.

MENTAL ILLNESS AND RISK OF CANCER

While the question of whether cancer causes mental health illness is multifaceted and complex to answer simply, it is important to look at the situation from another angle as well – does the presence of mental illness increase the risk of developing cancer?

Johns Hopkins research suggests that people with severe mental illness, such as bipolar disorder, schizophrenia, and debilitating depression, are about 2.6 times more likely to develop cancer compared to the general population.

The reasons are similar to why cancer patients with depression have an increased mortality risk – lifestyle factors like poor diet, lack of exercise, and smoking may play a significant role in cancer risk. Women with schizophrenia and bipolar disorder are also less likely to have children, and childbearing is associated with a reduced risk of breast cancer.

In other words, the increased risk of cancer in people with mental illness is not due to the disease itself but rather to the unhealthy lifestyle choices that are often associated with mental illness.

Much yet has to be done in order to raise awareness of this issue and to find ways to support people with mental illness in making healthy choices that can reduce their cancer risk.

CONCLUSION

Overall, it is clear that cancer can significantly impact mental health, whether directly or indirectly.

One way cancer could cause personality and behavior changes is by invading and damaging parts of the brain.

Cancer can also indirectly lead to negative psychological effects through the stress of the diagnosis and treatment process and the lifestyle choices that are often associated with mental illness.

At the same time, having mental illness, especially serious mental illness, can increase a person’s risk of developing cancer, most likely due to lifestyle factors.

Fortunately, mental health issues in a cancer survivor can often be treated effectively with psychotherapy and/or medication. It is important that people who are experiencing symptoms of mental illness seek help from a medical professional in order to improve their overall health outcomes.

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