Getting to know
cancer
Cancer is a large group of diseases that can occur in almost any organ or tissue of the body, when abnormal cells grow uncontrollably, extend beyond their usual boundaries, and invade neighboring organs and/or spread to other parts of the body. The spread to other organs is called metastasis and is a major cause of cancer-related death. Cancer is also referred to as a neoplastic disease or malignant tumor.
Cancer is the second leading cause of death worldwide. Lung cancer, prostate cancer, colorectal cancer, stomach cancer, and liver cancer are the most common types of cancer among men. Among women, the most common types are breast cancer, colorectal cancer, lung cancer, cervical cancer, and thyroid cancer.
The disease is growing at an increasing rate worldwide, with significant physical, psychological, and economic impacts on individuals, their loved ones, their communities, and healthcare systems. Many healthcare systems in low- and middle-income countries are less prepared to address cancer, and a large number of cancer patients do not have access to timely diagnosis and treatment. In countries with strong healthcare systems, survival rates for many types of cancer are improving due to access to early diagnosis and high-quality treatment and care.
References: WHO. https://www.who.int/health-topics/cancer#tab=tab_1
Under normal conditions, cells grow and divide in a controlled manner (through a process called cell division), creating new cells that the body needs. Sometimes, this orderly process is disrupted, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells form tumors, which are masses of tissue. These tumors can be either benign or cancerous.
Cancerous tumors spread into or invade nearby tissues and may travel to other parts of the body to form new tumors (metastasis). Most types of cancer form solid tumors; however, blood-related cancers, such as leukemia, usually do not form solid tumors.
Cancer is a genetic disease caused by specific changes in genes that control how cells function, grow, and divide. These genetic changes may result from errors during cell division, damage to DNA caused by harmful substances in the environment, or inherited factors.
Normally, the body has mechanisms that limit cells with DNA damage before they develop into cancer. However, this ability of the body decreases with age. This is one of the reasons why the likelihood of developing cancer is higher at older ages.
Cancer in each person involves a unique combination of genetic changes. As cancer develops, additional changes occur. Even within the same tumor, different cells may have undergone different genetic alterations.
References: National Cancer Institute https://www.cancer.gov/about-cancer/understanding/what-is-cancer
The exact reasons why one person develops cancer and another does not are usually not easy to identify. However, research has shown that certain risk factors may increase a person’s chances of developing cancer. Cancer risk factors include exposure to chemicals or other substances, as well as certain habits. They also include conditions that people cannot control, such as age or family history.
Most risk factors are initially identified through epidemiological studies. In these studies, scientists examine large groups of people and compare individuals who develop cancer with those who do not. These studies may show that people who develop cancer are more or less likely to have certain habits or to be exposed to specific substances compared to those who do not develop cancer.
Such studies alone are not enough to prove that a habit or substance causes cancer. For example, the finding may be a random result, or the actual risk factor may be different from what is believed to have caused cancer. When multiple studies converge on a common correlation between a risk factor and an increased cancer risk, and when a potential mechanism is identified that could explain how a risk factor might actually cause cancer, scientists can have greater confidence in identifying the risk factors for cancer development.
Among the most studied known or probable risk factors for cancer are: age, smoking, alcohol consumption, carcinogenic substances, radiation and ultraviolet radiation, chronic inflammation, hormones, immunosuppression, infectious agents, and obesity.
Although some of these risk factors can be avoided, others — such as age — cannot. Limiting exposure to avoidable risk factors can reduce the risk of developing certain types of cancer.
Approximately 30-50% of cancer deaths could be prevented if key risk factors were changed or avoided, and if evidence-based prevention strategies were implemented.
The impact of cancer can also be reduced through early diagnosis and treatment of cancer patients. However, prevention remains the most effective long-term strategy for controlling cancer.
Changing habits or avoiding the following risk factors can significantly contribute to cancer prevention:
- Avoidance of smoking (both tobacco products and vaping products)
- Maintaining a healthy body weight
- A healthy diet with plenty of fruits and vegetables.
- Regular exercise
- Limited alcohol consumption
- Protected sex
- Vaccination for Hepatitis B and Human Papillomavirus (HPV)
- Reducing exposure to ultraviolet (UV) radiation
- Avoid unnecessary exposure to ionizing radiation (e.g., reducing occasional exposure, ensuring safe and appropriate medical use of radiation in diagnosis and treatment).
- Avoid urban air pollution and indoor smoke from household use of solid fuels
- Avoidance of urban air pollution and indoor smoke from the household use of solid fuels
- Regular medical check-ups and care
- Some chronic diseases are also risk factors for cancer
References: WHO. https://www.who.int/health-topics/cancer#tab=tab_1
National Cancer Institute https://www.cancer.gov/about-cancer/causes-prevention/risk
Global Cancer Observatory https://gco.iarc.fr/causes/
Cancer is more likely to respond to effective treatment when detected early, resulting in a higher chance of survival, as well as reduced morbidity and less costly treatment.
There are two different strategies that promote early detection:
- Early diagnosis identifies symptomatic cancer cases at the earliest possible stage.
- Screening aims to identify individuals with abnormalities that suggest a specific cancer or a precancerous stage of cancer before symptoms appear and to refer them immediately for diagnosis and treatment.
Treatment options include surgery, anti-cancer drugs, and/or radiotherapy, administered either alone or in combination. A multidisciplinary team of cancer professionals recommends the best possible treatment plan based on the tumor type, cancer stage, clinical and other factors. Treatment choice should be guided by patient preferences and take into account the capabilities of the healthcare system.
Palliative care, which focuses on improving the quality of life for patients and their families, is an integral part of cancer care. Survivorship care includes a detailed plan for monitoring cancer recurrence and detecting new cancers, assessing and managing long-term effects related to cancer and/or its treatment, and providing services to ensure that the needs of cancer survivors are adequately addressed.
References: WHO. https://www.who.int/health-topics/cancer#tab=tab_1