Cancer is a disease involving the noncontrolled growth and spread of abnormal cells
Caused by mutations in certain genes within cells
Can have differing characteristics depending on site of cancer and degree of spread
Relatively rare in childhood since it takes time for cells to mutate
Causes
- Inherited
- Radiation
- Tobacco
- Viruses
- Chemicals
Inheritance is part of mutation, since it passes cells that are easy to mutate
Cigarette smoking 23x risk of lung cancer
HPV cervical and oropharyngeal cancers
Cancer vs Tumor
- Cancer arise in any location and is malignant/aggressive
- Tumor is a collection of cancer cells and can be malignant/benign
Characteristics
- Proliferate rapidly
- Non-stop proliferation
- By stimulating the growth of new blood vessels for nutrient (angiogensis)
- Do no become specialized or die
90% of cancer deaths are due to metastasize
Classification
Pathologists classify by examining microscopically, assigning grades
The grade depends on how abnormal the cancer cell is compared to normal cell from that organ
The determinant of the optimal treatment
TNM Staging System
Taking bladder as an example
T
- T0: innermost layer of the bladder lining
- T1: connective tissue beneath the bladder lining
- T2: muscle under the connective tissue layer
- T3: all the way through the muscle layer into the fat layer
- T4: spread outside the bladder
N
- N0: no cancer cells have entered the local lymph nodes
- N4: extensive involvement
M
- M0: no metastasis
- M1: metastasis
T2 N0 M1 is possible since cancer can spread through blood stream
Treatment
Early detection of cancer is difficult because there is no symptoms
Many patients receive multimodality treatment
Surgery
Biopsies are surgically removed and the type and stage of the tumor can be determined by microscopic analysis
- Local therapy
- Resection - removes the tissue containing the malignant cells
Instruments
- Endoscopes
- Minimally invasive surgery
- Allow physicians to look inside the body, take picture, take small pieces of tissues from internal organs for biopsy
Radiation Therapy
- Local therapy
- High-energy electromagnetic rays focused at the site of cancer
- Ionizing radiation can eject or deviate electrons from molecules in its path
- Free electrons damage the cells by causing chemical changes in DNA in the cell nucleus
Since our body has efficient repair mechanism, we can produce new cells and repair DNA damage
Chemotherapy
- Systemic, act on any cells within the body
- Killing normal cells too
> 50% of patients will receive chemotherapy, usually for late stage since the cancer have already spread
Hormonal therapy
Hormone instead of drug is used to influence tumor growth. For example, breast and prostate are responsive to hormones
Biological therapy
Stimulate the natural ability of the immune system to eliminate malignant cells from the body.
Enhance or supplement this natural response