Brief but Comphrehensive Knowledge on Cancers

 

Dear Nazlan

As promised to your request in the comment column under my article on exercise and jogging, allow me to very briefly run through this enormously vast subject on Cancer. Though very briefly explained, it is very comprehensive covering almost all areas on cancer that I know. 

First, let us look at the cellular biology of cancer. The normal cell functioning is that cells are the basic units of life, and their growth, division, and death are tightly regulated processes. Normal cells undergo a series of phases known as the cell cycle, which ensures proper DNA replication and division. Apoptosis, or programmed cell death, is a mechanism that removes damaged or unnecessary cells.

However, cancer arises when cells lose the ability to control their growth and division. Unlike normal cells, cancer cells exhibit uncontrolled proliferation. They evade apoptosis (programmed self-destruction). These cells than acquire the ability to invade surrounding tissues and spread to distant sites (metastasis). Then they managed to grow new blood vessel to supply them to the malignant tumour (angiogenesis) and sustain angiogenesis.

The study of cancer involves molecular and genetic biology of this disease. Cancer is fundamentally a genetic disease caused by mutations in specific genes. These mutations can be inherited (germline mutations) or acquired (somatic mutations) due to environmental factors such as radiation, chemicals, and viruses.

Cancer involves oncogenes and tumour suppressor genes. Oncogenes means mutations in these genes result in the gain of function, leading to uncontrolled cell growth. Examples include the RAS and MYC genes.

But Nature is such she tries to supress cancer by using tumour suppressor genes. These genes normally inhibit cell division and promote apoptosis. Mutations result in the loss of function, allowing unchecked cell growth. Examples include TP53 and RB1.

Then there is this DNA repair mechanisms. Cells have mechanisms to repair DNA damage. Defects in these repair mechanisms can lead to cancer. For instance, mutations in BRCA1 and BRCA2 genes increase the risk of breast and ovarian cancers.

Then comes our immune system against cancer. We have what we call Immunological Surveillance.  The immunological system plays a crucial role in recognizing and destroying abnormal cells. Immune cells such as T-cells and natural killer (NK) cells can detect and kill cancer cells.

However, there is also what we call Immune Evasion. This means cancer cells can evade the immune system through various mechanisms, such as downregulating antigen presentation. Next, they produce immunosuppressive molecules. They then create an immunosuppressive tumour microenvironment.

What about the classes and types of cancers? Based on tissue of origin, cancers are classified as carcinomas if they arise from epithelial cells (e.g., breast, lung, colon cancers). Sarcomas are cancers originating from connective tissues (e.g., bone, muscle cancers). Next, we have leukaemia. These are cancers of the blood and bone marrow. Lymphomas are cancers of the lymphatic system.

There are also Central Nervous System Cancers (CNSC). These are cancers of the brain and spinal cord.

What about the causes of cancer?

First, we have the environmental factors. I should say the most common is from tobacco smoke. These smokes contain carcinogens that can cause lung cancer and other types. Second, there is cancer-causing radiation such as UV radiation from the sun can cause skin cancer; ionizing radiation can cause various cancers.

Chemicals too can cause cancers.  Exposure to asbestos, benzene, and other chemicals can increase cancer risk.

A lot of people think that infections by germs causes only infectious diseases, whereas cancer is not an infectious disease. In truth, certain viruses (e.g., HPV, Hepatitis B and C) and bacteria (e.g., H. pylori) are associated with cancer.

The most important cause of cancer I should put it are lifestyle factors. Top on this list is Diet and Nutrition.  Poor diet, obesity, and alcohol consumption are linked to increased cancer risk.

Next may come to physical activity. The lack of physical activity can increase the risk of certain cancers.

Genetic factors and family history are also trigger factors.  Inherited mutations can predispose individuals to certain cancers.

 Most important considerations on the prevention of cancer are lifestyle modifications. This, I think is the most important preventive measure.

For this, avoidance of tobacco is probably the most important.  This itself reduces the risk of lung and other cancers.

 Next, adopt a healthy diet. Consider health-protective nutrition. As a nutritionist also, I would advise consuming lots of fruits and vegetables, especially a variety of coloured ones, whole grains, and reducing red and processed meats. See my write-up on poisons in foods

 Consider physical activity Regular moderate exercise (not jogging) can lower the risk of breast, colon, and other cancers. If you are a drinker, limiting alcohol consumption reduces the risk of cancers of the mouth, throat, liver, breast, and colon.

 Sun protection against ultraviolet light by using sunscreen and protective clothing to prevent skin cancer.

 Vaccinations too may help. HPV vaccines are shown to prevent cervical, anal, and other cancers. Then we also have hepatitis B vaccine. This vaccine reduces the risk of liver cancer.

 Regular screening tests (e.g., mammograms, colonoscopies) can detect cancers early when they are most treatable.

 We shall now very briefly talk about the treatment of cancer

 Previous treatments are mostly surgery for the removal of the tumour and surrounding tissue. Then there is this radiation therapy using high-energy radiation to kill cancer cells. Most common beyond surgery is chemotherapy by using drugs to kill or slow the growth of cancer cells.

But what about more current treatments when traditional treatments using surgery, chemotherapy and radiotherapy may not be the choice?

Here we have Targeted Therapy to offer. These are drugs that specifically target cancer cell molecules (e.g., HER2 inhibitors for breast cancer). Next, scientists came out this immunotherapy, treatments that boost the body's immune system to fight cancer (e.g., checkpoint inhibitors, CAR-T cell therapy).

Scientists have offered doctors the choice of Hormone Therapy for cancers that are hormone-sensitive (e.g., tamoxifen for breast cancer). Scientists have also worked on precision medicine. This is a tailoring treatment based on the genetic profile of the patient.  

 Let us now look at cancer treatment outlook and prognosis.  What are the factors influencing prognosis or outcome?

This depends on cancer type and stage. Early-stage cancers have a better prognosis.

Tumour grade means, the appearance of cancer cells under the microscope; high-grade tumours are more aggressive. We also consider the patient's health. Overall health and comorbidities affect the ability to tolerate treatment. Patients may already be too weak to receive any treatment if there was a delay.

The survival rates depend on the advancements in detection and treatment. Currently there have improved survival rates for many cancers. For example, the 5-year survival rate for breast cancer is now around 90%, and for prostate cancer, it is over 95%.

 What about future directions? This depends on how genius our cancer scientists are coming up with their research and innovation. We depend solely and entirely on them. They have already come up with Genomics and Personalized Medicine. This in simple language means, their ability to identify genetic mutations and tailoring treatments.

Our next hope lies in immunotherapy. Scientists are now developing new immunotherapeutic agents and combination therapies for oncologists to use.

They have also come out with early detection technologies, such as liquid biopsies and advanced imaging techniques for early diagnosis.

 But I think, above all, is public health initiatives. This involves awareness campaigns through education.  The public needs to be taught about risk factors and prevention. Next comes screening programs.  Increasing access to cancer screening and early detection services.

 To summarize all the above, cancer is a complex and multifaceted disease influenced by genetic, environmental, and lifestyle factors. Advances in molecular biology, genetics, and immunology have revolutionized our understanding and treatment of cancer. Preventive measures, early detection, and personalized treatments hold the promise of further improving outcomes for cancer patients. Continued research and public health efforts are crucial in the fight against this formidable disease.

I am sorry I have to explain this very vast and highly complicated subject very briefly using the simplest non-technical language for the benefit of ordinary readers, leaving out all the technical terms, scientific details and their descriptions. 

 But for medical researchers, expert oncologists, and those high-flown and well-versed biomedical scientists who want details, I have given them below a few technical references, books, journals, and papers published.

These references should provide a solid foundation for understanding the various aspects of cancer discussed

 I hope this helps and is useful for everyone.

 Kind regards 

ju-boo lim  

References and Studies:

1. Cancer Biology and Genetics:
• Weinberg, R. A. (2013). The Biology of Cancer. Garland Science.
• This textbook provides a comprehensive overview of the biological and genetic mechanisms of cancer.
• Hanahan, D., & Weinberg, R. A. (2011). "Hallmarks of Cancer: The Next Generation." Cell, 144(5), 646-674.
• This seminal paper discusses the fundamental traits that characterize cancer cells.
2. Immune System and Cancer:
• Chen, D. S., & Mellman, I. (2017). "Elements of Cancer Immunity and the Cancer–Immune Set Point." Nature, 541(7637), 321-330.
• This paper explores the interactions between cancer and the immune system and the concept of the cancer-immune set point.
• Schreiber, R. D., Old, L. J., & Smyth, M. J. (2011). "Cancer Immunoediting: Integrating Immunity's Roles in Cancer Suppression and Promotion." Science, 331(6024), 1565-1570.
• This study describes the dual roles of the immune system in both suppressing and promoting cancer.
3. Causes of Cancer:
• International Agency for Research on Cancer (IARC). (2012). "IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Volume 100 – A Review of Human Carcinogens."
• This series of monographs evaluates various environmental and lifestyle factors that are known carcinogens.
• Anand, P., Kunnumakkara, A. B., Sundaram, C., Harikumar, K. B., Tharakan, S. T., Lai, O. S., ... & Aggarwal, B. B. (2008). "Cancer Is a Preventable Disease That Requires Major Lifestyle Changes." Pharmaceutical Research, 25(9), 2097-2116.
• This paper discusses the role of lifestyle changes in cancer prevention.
4. Cancer Prevention:
• World Cancer Research Fund / American Institute for Cancer Research. (2018). Diet, Nutrition, Physical Activity and Cancer: A Global Perspective.
• This report summarizes the evidence on how diet, nutrition, and physical activity influence cancer risk.
• Kushi, L. H., Doyle, C., McCullough, M., Rock, C. L., Demark-Wahnefried, W., Bandera, E. V., ... & American Cancer Society 2010 Nutrition and Physical Activity Guidelines Advisory Committee. (2012). "American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention: Reducing the Risk of Cancer with Healthy Food Choices and Physical Activity." CA: A Cancer Journal for Clinicians, 62(1), 30-67.
• This paper provides guidelines for cancer prevention through diet and physical activity.
5. Cancer Treatment:
• National Cancer Institute. (2020). "Types of Cancer Treatment."
• This resource provides an overview of the various types of cancer treatments available.
• Siegel, R. L., Miller, K. D., & Jemal, A. (2020). "Cancer Statistics, 2020." CA: A Cancer Journal for Clinicians, 70(1), 7-30.
• This article provides statistics on cancer incidence, mortality, survival, and treatment.
6. Prognosis and Future Directions:
• Vogelstein, B., Papadopoulos, N., Velculescu, V. E., Zhou, S., Diaz, L. A., & Kinzler, K. W. (2013). "Cancer Genome Landscapes." Science, 339(6127), 1546-1558.
• This paper discusses the genomic alterations in cancer and their implications for treatment.
• Sharma, P., Hu-Lieskovan, S., Wargo, J. A., & Ribas, A. (2017). "Primary, Adaptive, and Acquired Resistance to Cancer Immunotherapy." Cell, 168(4), 707-723.
• This study explores the mechanisms of resistance to cancer immunotherapy and potential strategies to overcome it.