Cancer
- Cancer, also known as maglignant tumor or neoplasm, is an uncontrolled growth of cells caused by cumulation of genetic mutation. Cancers can happen in epithelial tissue in different organs and connective tissues in the body, the former is known as carcinoma and latter as sarcoma. Cancer in the blood is known as leukemia and is associated with abnormality in the bone marrow, lymphoma is cancer of the lymphatic system. Prompt and accurate diagnosis of cancer type and stage is paramount to different alternative treatment options in order to remove and prevent reoccurence of cancer tumor, prolonging patient's life expectancy.
- Some cancers stand a good chance of treatment without remission if detected early. Other cancers are more lethal when diagnosed due to the fact that they are more difficult to detect and are often discovered in later stages, pancreatic cancer is one of them.
- Cancer takes years to grow.
- Most common cancers are lung, breast, colon. There are different histologies to these cancer, examples for lung are non-small cell(nsclc) and small cell lung carcinoma. Nsclc is further divided up into lung adenocarcinoma, squamous cell lung cancer and large cell lung cancer.
Metastasis
- Metastasis occurs when cancer cells breaks off from the primary site and travel through the cirulatory and lymphatic system to develop at a secondary site.
- The seed and soil hypothesis states that there are most probable sites that are receptive to cancer cells that spread, for example prostate cancer typically spread to the bone.
- Since metastasis represent later stages of cancer development and is the cause of most deaths, I want to explain briefly the processes of metastasis. It typically follow these 8 steps:
- Primary tumor growth
- Angiogensis
- Epithelial to Mesenchumal Transition (EMT)
- Invasion
- Intravasation
- Survival in circulation
- Extravasation
- Dormancy and subsequent secondary growth
- For a variety of reasons, normal cells mutate and in some cases grow uncontrollably faster than normal cells would. To sustain fast rate of growth, it develops blood vessels to supply nutrient and oxygen. These blood vessels has weak structures and allows cancer cells that has acquired motile phenotype to seep into the circulatory system. These cancer cells then circulate in the vascular system but have to survive the pressure of blood flow through the heart and attack by the body immune system.
- Eventually some of these migrating cancer cells exit the circulatory system and settle at secondary sites - this is called extravasation. The cancer cells that land in 'congenial' secondary site may survive in dormant state before they start to proliferate.
- If any of these steps is stopped then metastasis can be prevented. Chemotherapy helps reduce cell division. When there is clear boundaries to cancer growth, surgical removal might be the best option, sometimes done in conjunction with chemotherapy (neoadjuvant). Radiation is another option.
- Modern oncology provides us more options through immunothreapy, targeted therapy and hormone therapy. Hormone therapy is applicable for breast and prostate cancer.
- Early detection is key to better options for treatment, detection are done through imaging and there has been some research on how to detect cancer cells in transit in the blood. Detection mechanisms include X-ray, CT-scan, MRI, colonoscopy and endoscopy. Computer vision is helping pathologists to locate and identify tumors from these imaging technologies.
Propensity to developing cancer
- Factors including family history, lifestyle, obesity, state of immune system affect likelihood of development of certain types of cancer in a person's life.
- Biomarkers HER2, ER, PR, BRCA1, BRCA2 can determine one's probability of developing breast cancer, similarly EGFR for lung cancer, known genes related to colon cancer are KRAS, APC and TP53.
Key entities
- cancer staging
- medication
- diagnosis
- treatment