CANCER
Overview
- Cancer is a highly dreaded disease that ranks as a major cause of death globally.
- India sees more than a million cases of cancer each year, with a significant number resulting in fatalities.
- The study of cancer, including its development, treatment, and control, has been a focal point of intense research in biology and medicine.
Mechanisms of Cancer Development
- Normal cell growth and differentiation are tightly regulated, but cancer cells exhibit a breakdown in these regulatory mechanisms.
- Normal cells display “contact inhibition,” which inhibits uncontrolled growth upon contact with other cells. Cancer cells lose this property.
- Cancer cells continuously divide, leading to the formation of cell masses known as tumors.
Types of Tumors
- Benign Tumors: These tumors remain localized and do not spread to other parts of the body, causing minimal damage.
- Malignant Tumors: Malignant tumors consist of rapidly growing neoplastic (tumor) cells that invade and damage surrounding normal tissues. They also compete for nutrients, which can affect nearby normal cells. Cells shed from malignant tumors can travel through the bloodstream to form new tumors at distant sites, a process known as metastasis.
Causes of Cancer
- The transformation of normal cells into cancerous neoplastic cells can be induced by various agents known as carcinogens.
- Carcinogens include physical, chemical, and biological factors:
- Physical Factors: Ionizing radiations such as X-rays and gamma rays, as well as non-ionizing radiations like UV, can damage DNA, leading to neoplastic transformation.
- Chemical Factors: Substances in tobacco smoke are major contributors to lung cancer.
- Biological Factors: Cancer-causing viruses known as oncogenic viruses carry viral oncogenes. Additionally, normal cells contain proto-oncogenes (c-onc) or cellular oncogenes that, when activated under specific conditions, can lead to oncogenic cell transformation.
Cancer detection and diagnosis
Early Detection
- Early detection of cancer is crucial for successful treatment.
- Methods for cancer detection include:
- Biopsy: A piece of suspected tissue is cut into thin sections, stained, and examined under a microscope by a pathologist (histopathological studies).
- Blood and Bone Marrow Tests: These tests can detect increased cell counts in the case of leukemias.
- Radiography: Utilizes X-rays for imaging.
- CT (Computed Tomography): Generates three-dimensional images of internal organs using X-rays.
- MRI (Magnetic Resonance Imaging): Uses strong magnetic fields and non-ionizing radiation to detect pathological and physiological changes in living tissue.
- Antibodies Against Cancer-Specific Antigens: Employed for detecting certain cancers.
- Molecular Biology Techniques: Applied to identify genes in individuals with inherited susceptibility to specific cancers, aiding in prevention by advising avoidance of carcinogens to which they are susceptible.
Cancer Detection Techniques
- Biopsy: Histopathological examination of tissue samples.
- Imaging Techniques: Radiography, CT, MRI for internal organ cancer detection.
- Blood and Bone Marrow Tests: To identify leukemias.
- Antibodies Against Cancer-Specific Antigens: Used for specific cancer detection.
- Molecular Biology Techniques: Identify genes in individuals with inherited cancer susceptibility for prevention.
Cancer Treatment
Common Approaches
- Common approaches to cancer treatment include:
- Surgery: Removal of cancerous tissues.
- Radiation Therapy: Lethal irradiation of tumor cells with protection for surrounding normal tissues.
- Chemotherapy: Use of chemotherapeutic drugs to kill cancerous cells. Some are specific to certain tumors.
- Combination Therapy: Most cancers are treated with a combination of surgery, radiation therapy, and chemotherapy.
Immune System Activation
- Tumor cells can evade detection and destruction by the immune system.
- Patients are administered substances known as biological response modifiers, such as α-interferon, to activate their immune system and aid in tumor destruction.
