Complications and Comorbidities of Cancer

Most people with cancer also have other health conditions. Some pre-existing conditions happen at the same time as cancer. Other conditions can develop because of cancer or cancer treatment.¹

Having another health condition can affect cancer treatment and care. This article covers common complications and comorbidities of cancer. Talk to your doctor about your specific situation.¹

What are comorbidities and complications?

Complications and comorbidities are health conditions that happen at the same time as another. But they have slight differences:¹

• Comorbidity – a condition that exists at the same time as another condition
• Complication – a condition that develops because of an existing condition or treatment

For example, diabetes may be a comorbidity of high blood pressure. They often coexist and share risk factors. But 1 does not directly cause the other. But high blood pressure can cause heart failure. So heart failure is a potential complication of high blood pressure.

What are comorbidities of cancer?

Over 75 percent of people with cancer have at least 1 comorbid condition. This is because cancer shares risk factors with many other conditions. Lifestyle choices, family history, age, immune system function, and other risk factors play a role.^1,2

People with cancer can have many other conditions. Some common comorbidities of cancer include:^1,2

• Autoimmune conditions
• Chronic stress or depression
• Dementia
• Diabetes
• Heart disease
• Infections, such as COVID-19
• Liver and kidney disease
• Lung and airway conditions
• Obesity

What are complications of cancer?

Cancer and its treatment can cause other conditions. Some complications of cancer treatment are temporary. Other complications may show up years later. Your risk of complications depends on many factors. Age, cancer type and stage, and treatment choices all play a role.^3,4

Some common complications of cancer or its treatment include:^3-5

• Anxiety and depression
• Brain or nerve problems, such as headaches and stroke-like symptoms
• Cancer that spreads or returns
• Chemical imbalances that lead to bladder problems
• Difficulty breathing
• Fatigue
• Immune system changes
• Nausea or diarrhea
• Pain, especially bone pain
• Sleep problems
• Weight loss

Talk to your doctor about your risk of complications. Discuss any symptoms that concern you. They can discuss medicines and other therapies to manage complications.

How do other conditions affect cancer treatment?

Comorbidities and complications can make it harder to manage cancer. The presence of another condition can influence treatment decisions. People with certain other conditions are less likely to receive chemotherapy. Chemotherapy can potentially worsen other conditions. Other conditions can potentially make chemotherapy side effects too serious.⁶

Age also plays a role. People with cancer are living longer because of advances in cancer treatment. Older people with cancer are more likely to have other conditions. Older people are also less likely to tolerate chemotherapy.⁶

How do other conditions affect cancer outcomes?

Other health conditions can have a negative effect on cancer outcomes. This is because other health conditions can:^1,2

• Lead to tumor growth or cancer spreading
• Delay cancer diagnosis
• Exclude participation in clinical trials
• Reduce quality of life
• Make it hard to maintain a healthy diet and exercise

Managing other health conditions can improve cancer outcomes. Talk to your healthcare team about your specific situation. They may work with doctors who specialize in other conditions. This can help make sure treatment decisions align with recommendations.