Other inherited conditions, such as Lynch syndrome, can increase the risk of colorectal and several other cancers.
A family history of cancer does not automatically mean that someone has an inherited cancer syndrome.
However, multiple relatives with related cancers, diagnoses at unusually young ages, or repeated cancers across generations may justify genetic counseling.
A healthcare professional can assess whether genetic testing is appropriate.
Smoking and Tobacco Exposure
Smoking is a major preventable risk factor for several cancers.
Tobacco smoke contains chemicals that damage DNA and contribute to cancer development.
Smoking is strongly associated with lung cancer and also increases the risk of cancers affecting the mouth, throat, esophagus, bladder, pancreas, kidney, and other organs.
Avoiding tobacco and secondhand smoke can reduce risk.
Alcohol Consumption
Alcohol consumption is associated with an increased risk of several cancers, including cancers of the breast, liver, mouth, throat, esophagus, and colorectal region.
Risk generally increases with greater alcohol consumption.
Reducing or avoiding alcohol can lower exposure to this risk factor.
Certain Infections
Some infections are linked to cancer development.
Examples include:
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Human papillomavirus (HPV), which can cause cervical and several other cancers.
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Hepatitis B and C viruses, which can contribute to liver cancer.
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Helicobacter pylori, which is associated with certain stomach cancers.
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Epstein-Barr virus, which is linked to some lymphomas and other malignancies.
Vaccination against HPV and hepatitis B can help prevent certain infection-related cancers.
Appropriate testing and treatment for infections can also reduce risk in some circumstances.
Obesity and Physical Inactivity
Excess body fat is associated with an increased risk of several cancers.
Possible mechanisms include chronic inflammation, changes in hormone levels, and metabolic disturbances.
Regular physical activity and maintaining a healthy weight can contribute to reducing risk.
However, cancer is a complex disease. A person who develops cancer should not be blamed for their diagnosis based on weight, diet, or lifestyle.
Many cancers occur in people who follow healthy habits.
Chapter 8: Can Cancer Be Prevented?
Not every cancer can be prevented.
Some cases are related to inherited genetic changes, random cellular mutations, or factors that cannot be controlled.
Nevertheless, evidence-based lifestyle choices and preventive healthcare can reduce the risk of developing several cancers.
Avoid Tobacco
Avoiding cigarettes and other tobacco products is one of the most important steps people can take to reduce cancer risk.
For those who smoke, quitting at any age provides health benefits.
Healthcare professionals can offer counseling, nicotine replacement therapy, and other evidence-based treatments to support smoking cessation.
Maintain a Balanced Diet
A balanced diet supports overall health.
Eating a variety of vegetables, fruits, whole grains, legumes, and other nutritious foods can help provide essential nutrients and support a healthy weight.
Limiting processed meat and moderating red meat consumption may also reduce colorectal cancer risk.
No individual food can prevent cancer, and no special diet should be promoted as a substitute for medical treatment.
Stay Physically Active
Regular physical activity supports cardiovascular health, metabolic function, and weight management.
Adults should aim for a consistent routine that fits their health and physical abilities.
Walking, cycling, swimming, strength training, and other activities can all contribute to a healthier lifestyle.
Protect Your Skin From Excessive Sun Exposure
Ultraviolet radiation from the sun and tanning devices can damage skin cells.
Practical precautions include:
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Seeking shade during periods of intense sunlight.
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Wearing protective clothing.
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Using broad-spectrum sunscreen.
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Reapplying sunscreen as directed.
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Avoiding indoor tanning beds.
People should also pay attention to new or changing skin lesions.
Follow Recommended Screening Guidelines
Screening aims to identify certain cancers or precancerous changes before symptoms appear.
Examples include screening for cervical, breast, and colorectal cancers.
The recommended age and frequency vary by country, cancer type, personal risk, and medical history.
Some people with inherited risk factors may need screening earlier than the general population.
Screening is different from diagnostic testing.
A person experiencing concerning symptoms should seek medical evaluation rather than waiting until their next routine screening appointment.
Chapter 9: Why Stage 4 Cancer Treatment Is Different for Every Patient
When someone receives a stage 4 cancer diagnosis, the next major challenge is determining the most appropriate treatment.
There is no universal treatment plan.
Doctors consider the cancer's origin, its molecular characteristics, the organs affected, previous treatment, symptoms, and the patient's overall health.
Chemotherapy
Chemotherapy uses drugs to destroy cancer cells or prevent them from dividing.
It may be used alone or alongside other treatments.
Some patients receive chemotherapy to shrink tumors, slow disease progression, relieve symptoms, or improve survival.
The side effects depend on the medication and individual response.
Possible effects include fatigue, nausea, hair loss, changes in blood counts, and increased infection risk.
Not every chemotherapy drug produces the same side effects.
Immunotherapy
Immunotherapy helps the immune system recognize and attack cancer cells.
Certain immunotherapies have changed treatment options for several advanced cancers.
However, they do not work for every cancer or every patient.
Some treatments are only appropriate when tumors have particular biomarkers or molecular characteristics.
Immunotherapy can also produce immune-related side effects affecting organs such as the lungs, liver, intestines, skin, or endocrine glands.
Medical monitoring is essential.
Targeted Therapy
Targeted therapies act on specific molecules or biological pathways involved in cancer growth.
These treatments may be particularly useful when testing identifies an alteration that can be targeted with an available drug.
Examples include therapies directed at certain mutations or abnormal proteins.
The suitability of targeted treatment depends on the cancer type and molecular test results.
Hormone Therapy
Some cancers depend on hormones for growth.
Hormone therapy can reduce hormone production or block hormone signals.
It is used in selected cancers, particularly certain breast and prostate cancers.
Its effectiveness depends on whether the tumor is hormone-sensitive.
Radiation Therapy and Surgery
Radiation therapy uses high-energy radiation to damage cancer cells.
In advanced disease, it may help control tumors in specific locations, relieve pain, reduce bleeding, or address other symptoms.
Surgery may also be appropriate in selected situations, depending on the cancer and treatment goals.
For some metastatic cancers, treatment focuses on controlling disease throughout the body rather than removing every visible tumor.
Palliative Care Is Not the Same as Giving Up
Palliative care focuses on improving quality of life for people living with serious illness.
It can help manage pain, nausea, fatigue, breathlessness, emotional distress, and other symptoms.
It may be provided alongside active cancer treatment at any stage of disease.