What is Cancer

There are over 100 different types of cancer. Each is named by the type of cell that is initially affected. Cancer is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body. Cancer harms the body when mutated, or altered cells divide uncontrollably to form lumps or masses of cancerous tissue called tumours. Tumours can be cancerous (malignant) or not cancerous (benign). Benign tumours stay in one spot and demonstrate limited growth. These are more easily treated than the more dangerous malignant tumours. Malignant tumours occur when a cancerous cell manages to move throughout the body using the blood or lymphatic systems, destroying healthy tissue in a process called the invasion or if that cell manages to divide and grow, making new blood vessels to feed itself. This process is called angiogenesis. Metastasis is a process that is caused when a tumour successfully spreads to other parts of the body and grows, invading and destroying other healthy tissues. Metastasised tissue is a serious condition and the most difficult to treat. Source: National Cancer Institute

What Causes Cancer?

1. Genes

If your family has a high incidence of a specific type of cancer, it is possible that you inherited genetic mutations that increase your susceptibility to certain cancers. Breast and colorectal cancer are examples of cancers that tend to run in families. Nevertheless, having a genetic mutation does not necessarily guarantee that you will develop cancer in the future; only about 5 to 10 percent of all cancers are directly attributed to inherited genetic mutations.

2. Smoking

There are many carcinogenic substances found in tobacco smoke, which can increase your likelihood of developing certain types of cancer, such as lung and oral cancer, as well as stomach, kidney, and bladder cancer. Any form of tobacco consumption is detrimental to your well-being.

3. Exposure to Second-hand Smoke

Second-hand smoke is equally hazardous to health. When a cigarette is lit, approximately 90% of the smoke is released into the air, which then becomes second-hand smoke. Even if you don’t smoke, being exposed to someone else’s smoke can raise your risk of developing lung cancer.

4. Sun and UV Exposure

Regularly exposing your skin to ultraviolet (UV) radiation, whether from direct sunlight or artificial sources like tanning beds, can cause harm and increase your chances of developing skin cancer.

5. Alcohol

Drinking alcohol leads to a higher risk of cancer, regardless of the quantity. The less alcohol you drink, the lesser your risk of cancer. Source: Singapore Cancer Society

Cancer Across the World

Breast and lung cancers were the most common cancers worldwide, contributing 12.5% and 12.2% of the total number of new cases diagnosed in 2020. Colorectal cancer comes in third with 1.9 million new cases in 2020, contributing 10.7% of new cases. The top three most common cancers in males are lung, prostate and colorectal cancers – contributing to 41.9% of all cancers (excluding non-melanoma skin cancer). Lung cancer was the most common cancer in men worldwide, contributing 15.4% of the total number of new cases diagnosed in 2020. For females, the top three most common cancers are breast, colorectal and lung cancers – contributing to 44.5% of all cancers (excluding non-melanoma skin cancer). Breast cancer was the most common cancer in women worldwide, contributing 25.8% of the total number of new cases diagnosed in 2020.

Men	% in 2020	Women	% in 2020
Lung	15.4	Breast	25.8
Prostate	15.1	Colorectal	9.9
Colorectal	11.4	Lung	8.8
Stomach	7.7	Cervix uteri	6.9
Liver	6.8	Thyroid	5.1

Source: World Cancer Research Fund International and American Cancer Society

Cancer in Singapore

For men, the three most common cancers are colorectal (16.5%), prostate (15.9%) and lung (13.6%) and for females the three most common cancers are breast (29.7%), colorectal (13%) and lung (7.9%).

Men	% in 2016 to 2020	Women	% in 2016 to 2020
Colon-rectum	16.5	Breast	29.7
Prostate	15.9	Colon-rectum	13
Lung	13.6	Lung	7.9
Liver	7.4	Uterus	7.2
Non-melanoma Skin	5.3	Lymphoid Neoplasms	5.1

Source: National Cancer Centre Singapore

References:
https://www.cancer.gov/about-cancer/understanding/what-is-cancer#definition
https://www.wcrf.org/cancer-trends/worldwide-cancer-data/
https://www.cancer.org/research/cancer-facts-statistics/global.html
https://www.cdc.gov/chronicdisease/resources/publications/factsheets/cancer.htm
https://www.nccs.com.sg/patient-care/cancer-types/cancer-statistics
https://www.singaporecancersociety.org.sg/learn-about-cancer/cancer-basics/what-causes-cancer.html

Dr Wong Seng Weng

At The Cancer Centre (TCC), Dr Wong Seng Weng and his medical oncology team are focusing their expertise on implementing preventive measures, actively conducting screening and providing innovative, targeted treatments for adult cancers, as well as using proven technologies to ensure optimal patient safety and comfort.

Dr Wong, a visiting consultant medical oncologist at Mount Elizabeth Hospital (Novena) and Mount Elizabeth Hospital (Orchard), holds the appointment of Adjunct Clinician Scientist at the Institute of Bioengineering and Nanotechnology in the Agency of Science, Technology and Research (A*STAR). He is also an active member of the American Society of Clinical Oncology, European Society of Medical Oncology and Singapore Society of Oncology.

What is Cancer

What Causes Cancer?

1. Genes

2. Smoking

3. Exposure to Second-hand Smoke

4. Sun and UV Exposure

5. Alcohol

Cancer Across the World

Cancer in Singapore

Dr Wong Seng Weng

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