Cancer is a disease which kills people every year all over the world. Even if this disease is killing people, human body has the ability to fight cancer and this disease is actually curable. People die because they either don’t get the right treatment at the right time or the body fails to fight cancer because of some genetic problem. Cancer is not exactly a hereditary disease and it can happen to anybody under certain circumstances.
Local symptoms: These symptoms are observed at the site of primary cancer. They include lump or swelling, bleeding, ulceration and pain. In some cases the initial sign can be only swelling without any pain.
Metastatic symptoms: These symptoms are observed after the cancer spreads to various parts of the body. They include lymph nodes (usually felt under the skin), hepatomegaly (liver enlargement) or splenomegaly (enlarged spleen) which can be felt in the abdomen, pain or fracture of effected bones and neurological symptoms.
Systemic symptoms: These are distant effects of cancer and are not related to metastatic spread. They include weight loss, fatigue, sweating, anemia (low red blood cell count) and other conditions like paraneoplastic phenomena. These symptoms occur as a result of immunological and hormonal signals from cancer cells.
Abnormal cell growth
In cancer, the normal healthy cells grow abnormally as a result of cell division and form a neoplasm or tumour. If that tumour is not healed properly then the cancer cells spreads to other adjacent parts of the body by invading other normal cells. If a cancer cell enters the blood stream then it could infect any part of the body.
Cancer can happen in various types of cells and they include:
Carcinoma: Cancer derived from epithelial cells. This type of cancer occurs in breast, prostate, lung and colon.
Germ cell tumour: Cancer derived from pluripotent cells. These are found in the testicle and ovary of adults but are more common in babies and young children.
Blastoma: Cancer derived from immature embryonic tissue. These are also common in children.
Causes
Cancer is caused mainly because of environmental problems and 90-95 per cent cancers are caused due to environmental factors. This means cancer can cause without any genetic reasons. Common environmental problems include tobacco use (25-30%), diet and obesity (30-35%), infections (15-20%), radiation (ionizing and non-ionizing, up to 10%) and other factors like stress, lack of physical exercise and environmental pollutants. However, the genetic factor applies along with these environmental factors but only 5-10% is due to genetic.
Cancer is also caused due to fungus (Aspergillus flavus) and Virus (Hepatitis B, Human papilloma). Taking some supplement like ß-carotene (naturally found in carrots) at about 30 mg/day could cause lung and prostate cancer in smokers.
Main cause of cancer is genetic mutation
Our body consists of billions of cells and each cell has its functionality stored in its gene. Every living organism consists of DNA (Deoxyribonucleic acid) and RNA (Ribonucleic acid). Each DNA or RNA contain gene which carries the information about the organism and how it functions. It’s more like software that gives instruction to the hardware (organism) to do certain functions like how to grow, multiply and absorb nutrients. Every organism grows only with the help of DNA or RNA and any alteration to the genetic information can effect the growth of cells. Mutation is a process through which the cell changes its behaviour and the growth pattern through the modification of the genetic information stored in the DNA or RNA. For example a virus can modify itself by copying the genetic information during replication and thus it can mutate itself to gain control of the immune system of the organism. This phenomenon can be applied to genetically modified (GM) crops. A cancer cell is formed as a result of the same phenomenon that is when the genetic information is changed. The shape and size of our body is programmed in the genetic code of our DNA and that’s why every human has almost similar body structure. Cells are not programmed to form tumors but when this software gets damaged due to any environmental factors then cells lose their control and forms tumors.
In our body, DNA damage is caused every day as a result of normal metabolism and environmental factors like ultraviolet (UV) light and radiation, resulting in 1 million molecular lesions per cell per day. DNA damage and alteration could cause harmful mutation to cell's genome, which affects the survival of its daughter cells after mitosis (cell division). The ability to repair the DNA depends on the integrity of the cell’s genome. Therefore people with weak DNA repair ability are more prone to cancer.
Substances or agents that can cause mutation are called mutagens. Some examples of mutagens include nitrosamine (present in tobacco), radio active polonium (present in tobacco), UV light, ionizing radiation like X-rays, etc.
Carcinogens are chemical substance that could cause damage and mutation to the DNA and cause cancer. Common examples of carcinogens are inhaled asbestos, certain dioxins, and tobacco smoke. Polycyclic Aromatic Hydrocarbons (PAH) are pollutants found in tobacco smoke and are also considered as carcinogens.
Oncogenes are genes that cause cancer when mutated. Oncogenes inhibit the apoptosis and causes cells to grow abnormally forming tumour.
Biotransformation in body is also responsible for cancer
Biotransformation is the process of elimination of toxic chemicals through various chemical reaction and making to more soluble with water. If the biotransformation of carcinogens are not done effectively and rapidly then the chance of mutation is high. Sometimes such reactions as a result of biotransformation could convert less toxic carcinogens to more toxic ones. Therefore people with effective biotransoformation are safe and that’s why most people taking too much of tobacco or toxic chemicals never develop cancer. Water plays an important in biotransformation and increasing daily water intake could enhance the biotranformation of the body. However biotranformation cannot protect anyone from harmful radiation and that’s why probability of cancer from radiation is high.
Our body is designed to fight tumours and protein p53 in our body destroys any tumours. It is considered as the guardian of the genome. In our body every cell is meant to die and commit suicide this is known as apoptosis. In our body almost 17 billion cells die every day but cancer cells don’t and when this happens protein p53 kills those cells that are not willing to die as a result of mutation. This process is carried out in relation with protein p21. Cell division is a process of cell division and when cells multiply in numbers, the growth of cells are controlled by p21. p21 sends the stop signal to protein cdk2 (cdk2 carries out the cell division and cell cycle) and thus apoptosis of tumour cell occurs. However when the gene of p53 gets mutated, the p53 cannot bind to the DNA and protein p21 doesn’t send stop signal to cdk2. As a result mutated gene is replicated during uncontrolled cell division and forms cancer cells or tumours. Certain virus or pathogens can also damage p53 protein and could make the body injurious to cancer.
Besides mutation, DNA damage could also lead to tumors but this may take time and may not cause cancer as quickly as mutation to p53 does. However, any DNA damage could lead to tumor but if the DNA of p53 is not damaged then such tumors are suppressed but if p53 gets damaged somehow from radiation then cancer is certain.
Leukemia - a different form of cancer
Leukemia is caused because of abnormal production of white blood cells (WBC) by the bone marrow inner tissue. Stem cells inside the bone marrow produces blood including WBC. However, any mutation or damage to the DNA of the stem cells or the inner tissue of the bone marrow causes abnormal production of WBC. This leads to weaker immune system and increased WBC count. Leukemia can be either chronic or acute and is caused due to exposure to mutagens or radiation. As in leukemia tumours don’t occur, the tumour suppressor protein p53 is helpless and cannot suppress leukemia. Here bone marrow transplant is the ultimate treatment provided.
Cancer cases as a result of radiation
Marie Curie who discovered the radioactivity died of Aplastic anemia in 1934 because she was exposed to radioactive agents. But her daughter Irène Joliot-Curie died of leukemia in 1956 due to exposure to plutonium as a result of accidental plutonium explosion in her lab in 1946. This proves that leukemia is caused due to strong radioactive exposure but why Marie Curie didn’t get leukemia? If Aplastic anemia is also caused as a result of radiation exposure then it is also caused due to DNA damage, I (author of this article) guess.
In a nuclear disaster of Ukraine, the Chernobyl Nuclear Power Plant exploded releasing nuclear compounds in the air. After this disaster, the children residing in that area suffered from thyroid cancer and workers who cleaned the plant flowing the disaster, are at higher risk of lung cancer as a result of radio active dust inhalation.
Use of mobile phone causes cancer
Use of mobile phones is rapidly increasing in this world and people are using mobile phone in everyday life. But people are not aware that there are many harmful effects of mobile phone use and once such harmful use is cancer. Mobile phone uses radio waves and radiation from mobile phone is similar to that of a microware oven. Every time we talk on the phone our brain cells gets heated up by the radiation from the mobile phone and no one is aware about it. Continues exposure to mobile phone radiation can lead to brain tumours but this is not same for everybody. It will vary from person to person and only those people will be affected who are using mobiles continuously throughout the day for many years. Other factors like gene and age will also depend on cancers caused from mobile radiation. Mobile base stations are more powerful than mobile phones and people who live close to a mobile base station are at health risk. It’s seen that people living very close to base stations often suffer from fatigue, headache, sleep disruption and memory problems.
A 2002 survey study by Santini et al. in France found a variety of self-reported symptoms for people who reported that they were living within 300 meters (984 ft) of GSM cell towers in rural areas, or within 100 meters (328 ft) of base stations in urban areas. Fatigue, headache, sleep disruption and loss of memory were among the symptoms reported.
A Swedish scientific team at the Karolinska Institute conducted an epidemiological study (2004) that suggested that regular use of a mobile phone over a decade or more was associated with an increased risk of acoustic neuroma, a type of benign brain tumour. The increase was not noted in those who had used phones for fewer than 10 years.
A German study (2006) that states "In conclusion, no overall increased risk of glioma or meningioma was observed among these cellular phone users; however, for long-term cellular phone users, results need to be confirmed before firm conclusions can be drawn.
In 2007, Dr. Lennart Hardell, from Örebro University in Sweden, reviewed published epidemiological papers and found that:
Cell phone users had an increased risk of malignant gliomas. Link between cell phone use and a higher rate of acoustic neuromas.
Tumors are more likely to occur on the side of the head that the cell handset is used.
One hour of cell phone use per day significantly increases tumor risk after ten years or more.
Treatments for cancer
Following are various types of treatments available for cancer:
1) Chemotherapy
2) Radiation therapy
3) Target therapy (New)
4) Surgery
5) Monoclonal antibody therapy
Chemotherapy
In chemotherapy, drugs are used to kill any cell which carries out cell division abnormally. As cell division occurs normally also, drugs used in this therapy also kills other cells which are not cancer cells but carries out cell division for normal functioning. Therefore this therapy is not much effective in treating cancer and causes a lot of side-effects to the body.
Radiation therapy
In radiation therapy, X-rays or gamma rays are used to damage the DNA of the cancer cells so that they won’t replicate. However radiation cannot penetrate the cancer tumors because of lack of oxygen in the tumors (hypoxic cell). This condition of the tumors is known as hypoxia. Therefore some radiosensitizers like misonidazole and metronidazole are used to improve the effectiveness of the radiation treatment on such tumors. This therapy is risky and may damage other normal cells if not used properly.
Target therapy
In this therapy, drugs are used to target certain molecules that are responsible for tumor growth and blocks tumor growth. This treatment is safer than chemotherapy and has less harmful effects on the body.
Surgery
With the help of surgery tumor cell is removed from the body. Surgery should be done very carefully because if the tissue from a tumor comes in contact with blood vessel then cancer cells can spread to the other parts of the body. Therefore surgery is only useful at the early stage to remove the primary tumour but is not effective after metastasis.
Monoclonal antibody therapy
Monoclonal antibodies are cells that target harmful cells in the body which immune cells cannot handle. In monoclonal antibody therapy, antibodies are prepared from other living cells and they are used in the body to target certain cells that are causing a disease. Therefore using antibodies to target cancer cells could cure cancer too and monoclonal antibody therapy could be the ultimate cure to cancer.
Conclusion
No matter what treatment is used to treat cancer, it’s only the gene that can help to fight against cancer. However cancer is not a hereditary disease and can happen to anyone due to the exposure to mutagens and carcinogen. Therefore avoiding harmful chemicals or hazardous environments is the only way to get rid of cancer. Smoking and chewing of tobacco cause cancer in most people and cancer is common in people who use tobacco daily. Taking lot of water and antioxidants can help to prevent cancer but some antioxidants like ß-carotene present in carrots can increase chance of lung cancer. Use of aspirin reduces the risk of death in cancer. Most vitamins have no effect on treating cancer but vitamin E helps in treating prostate cancer. Drugs like tamoxifen and raloxifene can reduce the risk of developing breast cancer by 50% if used on daily basis. If scientist could come up with some drugs that could assist the DNA repair function and enhance biotranformation to help the body detoxify from harmful mutagens then cancer could be prevented.
(The author can be reached at debojitacharjee@gmail.com