Cancer is a disease which refers to any one of a large number of diseases that are characterized by the development of abnomal cells which divide uncontrollably and they have ability to infiltrate and destroy the normal tissue of our bodies. There are many cases when the cancer can spread throughout our body. In the United States of America, cancer is the second leading cause of death . There are many improvements in the cancer screening and cancer treatment and this is improving the survival rates for many types of cancer.
Symptoms of cancer
The signs and symptoms which are caused by cancer will vary depending on what part of your body is affected. Here are some general signs and symptoms associated with, but not specific to, cancer:
- Unexplained bleeding or bruising
- Persistent, unexplained fevers of night sweats
- Persistent, unexplained muscle or joint pain
- Persistent indigestion or discomfort after eating
- Difficulty swallowing
- Persistent cough or trouble breathing
- Changes in bowel or bladder habits
- You can notice skin changes, such as yellowing, darkening or redness of the skin, sores that will not heal or changes to existing moles
- Weight changes, including unintended loss or gain
- Also you can have a lump or area of thickening that can be felt under the skin
If you have any persistent sign or symptoms that concern you, then you need to talk with your doctor as soon as possible. If you do not have any sign or symptom but you are worried about your risk of getting cancer, then you need to talk with your doctor.
causes of cancer
This disease is caused by mutations (changes) to the DNA within cells. The DNA which is inside a cell is packaged into a large number of individual genes and each of it has a set of instructions which are telling the cell what function to perform but also it is telling how to divide and grow. When there are errors in the instructions, then they can cause the cell to stop its normal function and they can allow a cell to become cancerous.
Risk factors: Doctors have an idea of what may increase the risk of cancer but the most cases of cancers happen in people who do not have any known risk factors. Here are factors which increase your risk of getting cancer:
- Your environment: We know that the environment around us can have harmful chemicals which can increase our risk of cancer. Even if you do not smoke, you might inhale secondhand smoke if you live with someone who smokes or you go where people are smoking. Chemicals in your workplace or home such as benzene and asbestos are also associated with an increased risk of cancer. 
- Your health conditions: There are some chronic health conditions such as ulcerative colitis which can increase your risk of developing certain types of cancers.  You need to talk with your doctor about the risk of developing cancer.
- Your family history: There is a small portion of cancers which are due to an inherited condition. If the cancer is common in your family, then it is possible that the mutations are being passed from one generation to the next generation. You need to make genetic testing to see if you have inherited mutations that are increasing your risk of certain cancers. But if you have inherited genetic mutation, then this does not mean that you will get cancer for sure. [4,5]
- Your habits: There are some lifestyle choices which can increase your risk of cancer. Having unsafe sex, being obese, frequent blistering sunburns, excessive exposure to the sun, drinking more than one alcoholic drink in a day (this is meant for women of all ages and men older than 65) or two drinks a day (for men age 65 and younger) and smoking are some factors which can contribute to cancer. 
- Your age: This disease can take decades to develop. This is a reason why many people who are diagnosed with cancer are 65 or older. This condition is most common in older adults but the cancer is not exclusively an adult disease. It can be diagnosed at any age.
Complications: Cancer and the treatments of cancer can cause several complications  including:
- Cancer that returns
- Cancer that spreads
- Unusual immune system reactions to cancer
- Weight loss
- Difficulty breathing
- Diarrhea or constipation
 Centers for Disease Control and Prevention. An update on cancer deaths in the United States. Retrieved from www.cdc.gov/cancer/dcpc/research/update-on-cancer-deaths/index.htm
 National Cancer Institute. Cancer-causing substances in the environment. Retrieved from www.cancer.gov/about-cancer/causes-prevention/risk/substances
 Zhou Q, Shen ZF, Wu B, et al. Risk of colorectal cancer in ulcerative colitis patients: A systematic review and meta-analysis. Gastroenterol Research and Practice. 2019;2019:5363261.
 Lowery JT, Ahnen DJ, Schroy PC, et al. Understanding the contribution of family history to colorectal cancer risk and its clinical implications: A state-of-the-science review. Cancer. 20161;122(17):2633-45.
 Cleophat JE, Nabi H, Pelletier S, et al. What characterizes cancer family history collection tools? A critical literature review. Current Oncology. 2018;25(4):e335–e350.
 Anand P, Kunnumakara AB, Sundaram C, et al. Cancer is a preventable disease that requires major lifestyle changes. Pharmaceutical Research. 2008;25(9):2097–116.
 Bademler S, Üçüncü M, Yildirim I, Karanlik H. Risk factors for complications in cancer patients with totally implantable access ports: A retrospective study and review of the literature. Journal of International Medical Research. 2019;47(2):702–9.